Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Mirabilis”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3Linked to original sources
PubMed2002

The Helicobacter pylori flbA flagellar biosynthesis and regulatory gene is required for motility and virulence and modulates urease of H. pylori and Proteus mirabilis.

Helicobacter pylori and Proteus mirabilis ureases are nickel-requiring metallo-enzymes that hydrolyse urea to NH3 and CO2. In both H. pylori and in an Escherichia coli model of H. pylori urease activity, a high affinity nickel transporter, NixA, is required for optimal urease activity, whereas the urea-dependent UreR positive transcriptional activator governs optimal urease expression in P. mirabilis. The H. pylori flbA gene is a flagellar biosynthesis and regulatory gene that modulates urease activity in the E. coli model of H. pylori urease activity. All flbA mutants of eight strains of H. pylori were non-motile and five had a strain-dependent alteration in urease activity. The flbA gene decreased urease activity 15-fold when expressed in E. coli containing the H. pylori urease locus and the nixA gene; this was reversed by disruption of flbA. The flbA gene decreased nixA transcription. flbA also decreased urease activity three-fold in E. coli containing the P. mirabilis urease locus in a urea- and UreR-dependent fashion. Here the flbA gene repressed the P. mirabilis urease promoter. Thus, FlbA decreased urease activity of both H. pylori and P. mirabilis, but through distinct mechanisms. H. pylori wild-type strain SS1 colonised gerbils at a mean of 5.4 x 10(6) cfu/g of antrum and caused chronic gastritis and lesions in the antrum. In contrast, the flbA mutant did not colonise five of six gerbils and caused no lesions, indicating that motility mediated by flbA was required for colonisation. Because FlbA regulates flagellar biosynthesis and secretion, as well as forming a structural component of the flagellar secretion apparatus, two seemingly unrelated virulence attributes, motility and urease, may be coupled in H. pylori and P. mirabilis and possibly also in other motile, ureolytic bacteria.

Animals↗
PubMed1993

The cleavage of immunoglobulin G in vitro and in vivo by a proteinase secreted by the urinary tract pathogen Proteus mirabilis.

Eighteen different strains of Proteus mirabilis were all shown to produce an EDTA-sensitive proteinase of c. 50 kDa that cleaved the heavy chain, but not the light chain, of IgG. Digestion of pure IgG with small amounts of pure P. mirabilis proteinase generated Fabc'2 and Fab'2 fragments; greater amounts generated Fab and Fc fragments that were comparable in size to those generated by pepsin and papain, respectively. Incubation of neutrophils with IgG digested with P. mirabilis proteinase or papain resulted in a marked decrease in the respiratory burst activity of the neutrophils that coincided with cleavage of the IgG into Fab and Fc fragments. Analysis of urine from patients with P. mirabilis urinary tract infection revealed in many the presence of Fab and Fc fragments of IgG indistinguishable in size from those generated by P. mirabilis proteinase. These results indicate that, in P. mirabilis urinary tract infections, the proteinase is secreted and cleaves IgG to fragments that have defective immune effector functions, thereby limiting the effectiveness of the immune response.

Adolescent↗
PubMed1995

The detection of raised levels of IgM to Proteus mirabilis in sera from patients with rheumatoid arthritis.

An analysis by ELISA of 100 rheumatoid factor (RF)-positive sera selected at random from a collection of sera from patients with various auto-immune diseases and joint pains, and 100 RF-negative sera from the same collection matched by patient age and gender, showed that the RF-positive sera had highly significantly (p < 0.0001) raised levels of IgM antibody, but not IgG antibody, to Proteus mirabilis over those of the RF-negative sera. This response was subsequently found to be associated with sera from patients who clinically had rheumatoid arthritis (RA). Sera from the RA patients had significantly greater amounts (p = 0.026) of IgM antibody to P. mirabilis than to the other organisms tested and these values were also highly significantly different (p < 0.0001) from P. mirabilis IgM antibody levels in matched RF-negative sera. Sera from RA patients also had significantly greater amounts of IgA to P. mirabilis (p < 0.0001) and greater amounts of IgM to Escherichia coli (p < 0.0001) and Klebsiella pneumoniae (p < 0.0001) than those in matched RF-negative sera. Other classes of antibody to these organisms and all classes of antibody to Pseudomonas aeruginosa were not raised in the sera of RA patients over those of RF-negative controls. The IgM response in RA patients was not specific for only one O serotype of P. mirabilis but was associated with all 11 different O serotypes of P. mirabilis tested and those of other Proteus spp. Moreover, the IgM antibodies to Proteus spp. appeared to be independent from C-reactive protein and RF.(ABSTRACT TRUNCATED AT 250 WORDS)

ATP-Binding Cassette Transporters↗
PubMed1991

Typing of Proteus mirabilis from clinical sources by computerized analysis of electrophoretic protein patterns.

Seventy-five strains of Proteus mirabilis (mainly of human origin) were characterized by one-dimensional SDS-PAGE of cellular proteins. The strains came from various countries; 24 were from urine, 17 from faeces (including one from a dog and one from a monkey), 12 from the respiratory tract (including nine from sputum), four from a cerebral abscess, 12 from miscellaneous sources and six from unknown sources. The protein patterns, which contained 45 to 50 discrete bands, were highly reproducible. The patterns of the 75 P. mirabilis cultures plus those of the type strains of six Proteus and Providencia species were used as the basis for two numerical analyses. In the first, which included all the protein bands, the P. mirabilis cultures formed nine clusters at the 85% S level. In the second analysis, in which the principal protein bands (in the 34.0-44.6 kDa range) were excluded, 74 of the 75 cultures of P. mirabilis formed a single cluster at the 77% S level distinct from the six Proteus and Providencia reference strains. The P. mirabilis strain which failed to cluster with the others had a background band pattern typical of the species in the lower molecular weight region but appeared to be less typical in the heavier bands. It is concluded that high resolution PAGE combined with computerized analysis of protein patterns provides the basis for typing clinical strains of P. mirabilis. Reference strains of each of the nine PAGE types identified are available from NCTC for inclusion in future studies.

Animals↗
PubMed1990

A proteolytic enzyme secreted by Proteus mirabilis degrades immunoglobulins of the immunoglobulin A1 (IgA1), IgA2, and IgG isotypes.

Proteus mirabilis strains associated with human urinary tract infections have previously been shown to secrete an extracellular metalloproteinase which cleaves serum immunoglobulin A (IgA). The enzyme has now been purified to apparent homogeneity from culture supernatants of P. mirabilis 64676. The protease activity is associated with a 50-kilodalton (kDa) protein. Unlike that of the classic IgA1 proteases, the substrate specificity of the P. mirabilis protease has been found to extend to both sublcasses of IgA, IgG, and the nonimmunoglobulin substrates, secretory component and casein. Cleavage of IgA1 and IgA2 by the P. mirabilis protease yielded fragments on sodium dodecyl sulfate-polyacrylamide gel electrophoresis whose sizes were consistent with a cleavage site outside the hinge region. Both secretory IgA1 and IgA2 were also cleaved by P. mirabilis protease, although the secretory IgA2 molecule was less readily cleaved than secretory IgA1. Free and IgA-bound secretory components were degraded to some extent by P. mirabilis protease. Cleavage of IgG, however, occurred at the hinge region as a two-stage process. The first stage was pepsinlike and generated an F(ab')2 fragment of 120 kDa and a small pFc fragment detected on nonreduced polyacrylamide gels. In the second stage, the F(ab')2 product was cleaved to yield papainlike Fab and Fc fragments, visualized as a diffuse band of 40 to 50 kDa.

Chromatography↗
PubMed1991

Cytotoxicity of the HpmA hemolysin and urease of Proteus mirabilis and Proteus vulgaris against cultured human renal proximal tubular epithelial cells.

Proteus mirabilis, a common agent of nosocomially acquired and catheter-associated bacteriuria, can cause acute pyelonephritis. In ascending infections, bacteria colonize the bladder and ascend the ureters to the proximal tubules of the kidney. We postulate that Proteus species uses the HpmA hemolysin and urease to elicit tissue damage that allows entry of these bacteria into the kidney. To study this interaction, strains of Proteus mirabilis and P. vulgaris and their isogenic hemolysin-negative (hpmA) or isogenic urease-negative (ureC) constructs were overlaid onto cultures of human renal proximal tubular epithelial cells (HRPTEC) isolated from kidneys obtained by immediate autopsy. Cytotoxicity was measured by release of soluble lactate dehydrogenase (LDH). Two strains of P. mirabilis inoculated at 10(6) CFU caused a release of 80% of total LDH after 6 h, whereas pyelonephritogenic hemolytic Escherichia coli CFT073 released only 25% at 6 h (P less than 0.012). Ten P. mirabilis isolates and five P. vulgaris isolates were all hemolytic and cytotoxic and produced urease which was induced by urea. The HpmA hemolysin is apparently responsible for the majority of cytotoxicity in vitro since the hemolysin-negative (hpmA) mutants of P. mirabilis and P. vulgaris were significantly less cytotoxic than wild-type strains. P. mirabilis WPM111 (hemolysin negative) was used to test the effect of urease-catalyzed urea hydrolysis on HRPTEC viability. In the presence of 50 mM urea, WPM111 caused the release of 42% of LDH versus 1% at 6 h in the absence of substrate (P = 0.003). We conclude that the HpmA hemolysin of Proteus species acts as a potent cytotoxin against HRPTEC. In addition, urease apparently contributes to this process when substrate urea is available.

Bacterial Proteins↗
PubMed1994

Effect of lipopolysaccharide (LPS) chain length on interactions of bactericidal/permeability-increasing protein and its bioactive 23-kilodalton NH2-terminal fragment with isolated LPS and intact Proteus mirabilis and Escherichia coli.

The target-specific cytotoxicity for gram-negative bacteria and the endotoxin-neutralizing activity of the 55-kDa bactericidal/Permeability-increasing protein (BPI) and its bioactive 23-kDa NH2-terminal fragment depend on the strong attraction of BPI for the lipid A region of lipopolysaccharides (LPS). We have shown before that smooth gram-negative bacteria with long-chain LPS are more resistant to BPI (especially holo-BPI) than are rough strains. It has been suggested that the high BPI resistance of some gram-negative bacteria, such as Proteus mirabilis, might also reflect the structural diversity of lipid A. To explore this possibility, we compared the antibacterial activity and binding of natural and recombinant holo-BPI and a recombinant NH2-terminal fragment (rBPI-23) to an isogenic rough (Re-LPS chemotype) and a smooth (S-LPS chemotype) strain of P. mirabilis and to LPS isolated from the two strains. Holo-BPI and rBPI-23 were both potently active against the Re strain of P. mirabilis (90% lethal dose, 20 nM). In contrast, the smooth strain was > or = 100 times more resistant to holo-BPI but only 10 times more resistant to rBPI-23. rBPI-23 was also more potent against several Escherichia coli strains from clinical bacteremia isolates. Differences in the antibacterial potency of BPI toward the Re and S strains of P. mirabilis correlated with differences in the binding of holo-BPI and rBPI-23 to these bacteria. In contrast, the binding of biosynthetically (in vitro transcribed and translated) 35S-labeled holo-BPI and NH2-terminal fragment to isolated Re- and S-LPS from P. mirabilis in solution was similar. Moreover, in the Limulus amebocyte lysate assay, holo-BPI and rBPI-23 potently neutralized both forms of LPS with equal effectiveness. Together, these results strongly suggest that BPI recognizes Proteus lipid A and that the relative resistance of (smooth) P. mirabilis to holo-BPI is due to the inhibitory effect of long polysaccharide chains of tightly packed LPS in the envelope.

Antimicrobial Cationic Peptides↗
PubMed1998

Use of green fluorescent protein to assess urease gene expression by uropathogenic Proteus mirabilis during experimental ascending urinary tract infection.

Proteus mirabilis, a cause of complicated urinary tract infection, expresses urease when exposed to urea. While it is recognized that the positive transcriptional activator UreR induces gene expression, the levels of expression of the enzyme during experimental infection are not known. To investigate in vivo expression of P. mirabilis urease, the gene encoding green fluorescent protein (GFP) was used to construct reporter fusions. Translational fusions of urease accessory gene ureD, which is preceded by a urea-inducible promoter, were made with gfp (modified to express S65T/V68L/S72A [B. P. Cormack et al. Gene 173:33-38, 1996]). Constructs were confirmed by sequencing of the fusion junctions. UreD-GFP fusion protein was induced by urea in both Escherichia coli DH5alpha and P. mirabilis HI4320. By using Western blotting with antiserum raised against GFP, expression level was shown to correlate with urea concentration (tested from 0 to 500 mM), with highest induction at 200 to 500 mM urea. Fluorescent E. coli and P. mirabilis bacteria were observed by fluorescence microscopy following urea induction, and the fluorescence intensity of GFP in cell lysates was measured by spectrophotofluorimetry. P. mirabilis HI4320 carrying the UreD-GFP fusion plasmid was transurethrally inoculated into the bladders of CBA mice. One week postchallenge, fluorescent bacteria were detected in thin sections of both bladder and kidney samples; the fluorescence intensity of bacteria in bladder tissue was higher than that in the kidney. Kidneys were primarily infected with single-cell-form fluorescent bacteria, while aggregated bacterial clusters were observed in the bladder. Elongated swarmer cells were only rarely observed. These observations demonstrate that urease is expressed in vivo and that using GFP as a reporter protein is a viable approach to investigate in vivo expression of P. mirabilis virulence genes in experimental urinary tract infection.

Animals↗
PubMed2002

Pathological and therapeutic significance of cellular invasion by Proteus mirabilis in an enterocystoplasty infection stone model.

Proteus mirabilis infection often leads to stone formation. We evaluated how bacterium-mucin adhesion, invasion, and intracellular crystal formation are related to antibiotic sensitivity and may cause frequent stone formation in enterocystoplasties. Five intestinal (Caco-2, HT29, HT29-18N2, HT29-FU, and HT29-MTX) and one ureter cell line (SV-HUC-1) were incubated in artificial urine with five Proteus mirabilis strains. Fluorescence-activated cell sorting (FACS), laser scanning microscopy, and electron microscopy evaluated cellular adhesion and/or invasion, pathologic changes to mitochondria, and P. mirabilis-mucin colocalization (MUC2 and MUC5AC). An MTT (thiazolyl blue tetrazolium bromide) assay and FACS analysis of caspase-3 evaluated the cellular response. Infected cells were incubated with antibiotics at dosages representing the expected urinary concentrations in a 10-year-old, 30-kg child to evaluate bacterial invasion and survival. All cell lines showed colocalization of P. mirabilis with human colonic mucin (i.e., MUC2) and human gastric mucin (i.e., MUC5AC). The correlation between membrane mucin expression and invasion was significant and opposite for SV-HUC-1 and HT29-MTX. Microscopically, invasion by P. mirabilis with intracellular crystal formation and mitochondrial damage was found. Double membranes surrounded bacteria in intestinal cells. Relative resistance to cotrimoxazole and augmentin was found in the presence of epithelial cells. Ciprofloxacin and gentamicin remained effective. Membrane mucin expression was correlated with relative antibiotic resistance. Cell invasion by P. mirabilis and mucin- and cell type-related distribution and response differences indicate bacterial tropism that affects crystal formation and mucosal presence. Bacterial invasion seems to have cell type-dependent mechanisms and prolong bacterial survival in antibiotic therapy, giving a new target for therapeutic optimalization of antibiotic treatment.

Anti-Bacterial Agents↗
PubMed2004

Ultrastructure of Proteus mirabilis swarmer cell rafts and role of swarming in catheter-associated urinary tract infection.

Proteus mirabilis is a common cause of catheter-associated urinary tract infection (C-UTI). It blocks indwelling urethral catheters through the formation of extensive crystalline biofilms. The obstruction of urine flow can induce episodes of pyelonephritis, septicemia, and shock. P. mirabilis exhibits a type of motility referred to as swarming, in which multicellular rafts of elongated, hyperflagellated swarmer cells form and move rapidly in concert over solid surfaces. It has been suggested that swarming is important in the pathogenesis of C-UTI. In this study we generated a set of stable transposon mutants deficient in swarming and used them to assess the role of swarming in the migration of P. mirabilis over urinary catheters. Swarming was found to be essential for migration over all-silicone catheters. Swarming-deficient mutants were attenuated in migration over hydrogel-coated latex catheters, but those capable of swimming motility were able to move over and infect these surfaces. A novel vapor fixation technique for the preparation of specimens and scanning electron microscopy were used to resolve the ultrastructure of P. mirabilis multicellular rafts. The flagellar filaments of P. mirabilis were found to be highly organized during raft migration and were interwoven in phase to form helical connections between adjacent swarmer cells. Mutants lacking these novel organized structures failed to swarm successfully. We suggest that these structures are important for migration and formation of multicellular rafts. In addition, the highly organized structure of multicellular rafts enables P. mirabilis to initiate C-UTI by migration over catheter surfaces from the urethral meatus into the bladder.

DNA Transposable Elements↗
PubMed1973

Studies on beta-galactoside transport in a Proteus mirabilis merodiploid carrying an Escherichia coli lactose operon.

Merodiploid derivatives bearing an F-linked lac operon (i(+), o(+), z(+), y(+), a(+)) from Escherichia coli were prepared from a Proteus mirabilis strain unable to utilize lactose and from a lac deletion strain of E. coli. A suitable growth medium was found in which the episomal element in the P. mirabilis derivative was sufficiently stable to allow induction of the episome-borne lac operon and thus to permit a comparison of the activities and properties of E. coli lac products in the intracellular environments of P. mirabilis and E. coli. In both derivatives the episomal lac operon was shown to be repressed in the absence of inducer. Kinetics of induction with gratuitous inducer (isopropyl-1-thio-beta-d-galactoside) were similar for both beta-galactosidase activity (beta-d-galactoside galactohydrolase, EC 3.4.1.23) and beta-galactoside transport activity in both derivatives, although the ratio of galactoside transport to beta-galactosidase activity was approximately 1.6-fold higher in the E. coli derivative. Comparison of beta-galactosidase and M-protein (lac y gene product)-specific activities indicated coordinate expression of the induced lac operon in both derivatives. Quantitatively, the maximal beta-galactosidase specific activity was two or three times higher for the E. coli derivative. A significant sodium azide inhibition (65% inhibition by 10 mM sodium azide) of lactose permease-mediated transport of o-nitrophenyl-beta-galactoside from an outside region of high concentration to an inside region of very low concentration ("downhill transport") was observed for the P. mirabilis derivative. Identical conditions for the E. coli derivative yielded only about 15% inhibition. Active transport of thiomethyl-beta-galactoside was similar for both derivatives, the major difference being that active transport was more sensitive to azide poisoning in the P. mirabilis derivative. Preliminary examination of the thiomethyl-beta-galactoside derivatives following active transport did not demonstrate the accumulation of a phosphorylated product in either strain but did reveal an unidentified derivative present in the P. mirabilis merodiploid extract which was not detectable in the E. coli merodiploid.

Azides↗
PubMed1976

Differentiation of Proteus mirabilis by bacteriophage typing and the Dienes reaction.

A provisional typing schema based on sensitivity to 23 bacteriophages has been established for Proteus mirabilis. Seventy-three bacteriophages were isolated on strains of P. mirabilis (64), P. vulgaris (1), P. morganii (7), and P. rettgeri (1), but those isolated on P. mirabilis were the most useful in differentiating other strains of . mirabilis. From the 73 phages studied, the best 23 were chosen by computer analysis for the provisional system, which was then used to study P. mirabilis infections in a 500-bed general hospital. All patient isolates for 19 months were saved and then compared by bacteriophage typing and the Dienes reaction in a retrospective study. There was evidence for only three instances of cross-infection or -colonization during this time. Bacteriophage typing was very sensitive in differentiating strains, since 200 strains were differentiated into 113 different lysis patterns and 94% were typable. The Dienes reaction was useful at times but often gave reactions that were difficult to read or that changed when the tests were repeated. The bacteriophages described by Schmidt and Jeffries were also evaluated and proved useful in combination with ours. The value of bacteriophage typing was clearly established, and work toward a standardized schema for P. mirabilis should continue.

Bacteriophage Typing↗
PubMed1992

Outer membrane protein profiles and multilocus enzyme electrophoresis analysis for differentiation of clinical isolates of Proteus mirabilis and Proteus vulgaris.

Outer membrane protein (MP) profiles and multilocus enzyme electrophoresis (MEE) analysis were used as tools for differentiating clinical isolates of Proteus spp. Fourteen distinct MP profiles were established by sodium dodecyl sulfate-urea polyacrylamide gel electrophoresis in 54 clinical isolates of Proteus spp. (44 strains identified as P. mirabilis and 10 strains identified as P. vulgaris). Forty-one isolates of P. mirabilis and eight isolates of P. vulgaris were grouped within six and three MP profiles, respectively. The remaining P. mirabilis and P. vulgaris isolates had unique profiles. MEE analysis was used to further discriminate among the strains belonging to the same MP groups. Thirty-five distinct electrophoretic types (ETs) were identified among P. mirabilis isolates. The isolates of P. mirabilis from the four most common MP groups were subgrouped into 30 ETs. All of the P. vulgaris strains had unique ETs. The results suggest that upon biochemical classification of Proteus isolates as P. mirabilis or P. vulgaris, further differentiation among strains of the same species can be obtained by the initial determination of MP profiles followed by MEE analysis of strains with identical MPs.

Bacterial Outer Membrane Proteins↗
PubMed2000

Complement activation by Proteus mirabilis negatively charged lipopolysaccharides.

Proteus mirabilis strains are human pathogens responsible for urinary tract infections and bacteremias and may be involved in rheumatoid arthritis. Lipopolysaccharide (LPS, bacterial endotoxin), the major component of the cell wall, is one of the virulence factors of Proteus. In the presented studies, we have investigated complement activation by LPSs isolated from P. mirabilis O10, O23, O30, and O43 strains, which differ in the number of negative COO- groups on their polysaccharide components. Four P. mirabilis strains studied were sensitive to complement-mediated killing, despite complement binding by their LPSs. The optimal complement binding by LPSs was detected in serum with functional assays for both the classical and alternative pathways. Complement activation in 80% serum by the smooth, uronic acid, and hexosamine containing P. mirabilis LPSs was not critically determined by the structure of their O-chain polysaccharides. One of four LPSs used as a model, P. mirabilis O10 LPS, fragmented C3 in an LPS dose- and time-dependent manner. It was detected by crossed-immunoelectrophoresis and capture ELISA with anti-C3c antibodies. The lower complement activation by 023 LPS correlates with its reduced C3 fragmentation, compared with three other Proteus LPSs studied. Rabbit anti-O antibodies enhanced the complement binding and factor C3 fragmentation by O10, O23, O30, and O43 P. mirabilis LPSs.

Animals↗
PubMedDate not supplied

[Clinical and pathogenetic significance of Proteus mirabilis antibodies in uveitis associated with joint lesions in children and adolescents].

Immunological studies in 95 children with uveitis associated with juvenile chronic arthritis revealed infection with Proteus mirabilis in 14.7% cases, mainly in cases with reactive arthritis and juvenile rheumatoid arthritis (JRA). A clear-cut relationship between P. mirabilis infection and severity of the disease was detected. In 85% children infected with P. mirabilis uveitis was associated with a rapid decrease of ocular functions and development of complications, one of the most frequent of which was vitreous fibrosis, generally not typical of classical rheumatoid uveitis. Antibodies to P. mirabilis were detected in 72.2% children with positive antinuclear factor, a marker of ophthalmoarticular rheumatic diseases. The pathogenetic significance of P. mirabilis in uveitis associated with articular involvement deserves further investigation, but even now the detection of P. mirabilis can be used as a marker of uveitis exacerbations and severity.

Adolescent↗
PubMed1979

DNA repair in Proteus mirabilis. VI. Plasmid (R46-) mediated recovery and UV mutagenesis.

The expression of plasmid R46-mediated recovery and mutagenic function (s) was studied in P. mirabilis, which is normally either weakly or non-mutable after UV exposure. The plasmid was found to confer on P. mirabilis enhanced UV resistance as well as UV-induced mutability for various types of forward mutations and reversion of the thr273 mutation. The plasmid enhanced survival of UV-irradiated phages in P. mirabilis both in unirradiated host cells and with increased efficiency after UV-exposure of host cells, as is characteristic of UV-inducible phage reactivation. Spontaneous mutability of P. mirabilis harboring R46 was about 2 to 7 times higher than that of cells without plasmid, depending on the marker, repair type, and plating density of the cells used. All of these R46-mediated rescue and mutagenic functions require the rec672 + gene function. It is assumed that the plasmid R46 adds functions to P. mirabilis comparable to those deficient in umuC and uvm mutants of E. coli (Kato and Shinoura, 1977; Steinborn, 1978) and that P. mirabilis possesses functions homologous to those controlled in E. coli by the recA + and lexA + genes. The significance of plasmid-mediated rescue and mutagenic functions for bacteria which lack the misrepair branch of mutagenesis, is discussed.

Animals↗
PubMed1983

Some biological features of Proteus bacilli. 2. Haemolytic activities of Proteus mirabilis and Proteus vulgaris strains.

The haemolytic activities of Proteus mirabilis and P. vulgaris strains were studied under different conditions. No filterable alpha haemolysin could be detected in P. mirabilis uropathogens provided from patients with urinary tract infections. Together with the results presented in the accompanying paper, in which three clinical isolates with temporary ability to produce a soluble haemolysin were described, the occurrence of alpha haemolytic P. mirabilis isolates did not exceed 3%. Cell bound beta haemolysin is present in nearly 35% of P. mirabilis urinary strains. Another kind of haemolytic activity was observed when P. mirabilis and P. vulgaris strains were grown in liquid media supplemented with erythrocytes. During the logarithmic growth phase nearly 100% of P. mirabilis and P. vulgaris strains of various origin haemolyzed 100-50% of erythrocytes. Except for Serratia, the other representatives of Enterobacteriaceae did not demonstrate such activity in the same conditions. The preliminary characteristics of this phenomenon is given.

Animals↗
PubMed2001

Temperature interactions of the molecular chaperone Hsc70 from the eurythermal marine goby Gillichthys mirabilis.

Molecular chaperones participate in many aspects of protein biogenesis. Mechanistically, they recognize and bind to non-native proteins, prevent the aggregation of unfolded proteins and also, in some cases, facilitate refolding. Although a great deal is known about the cellular function of molecular chaperones in general, very little is known about the effect of temperature on molecular chaperones in non-model organisms, particularly in ectotherms that fold proteins under variable-temperature conditions in nature. To address this issue, we studied the temperature interactions of a major cytosolic molecular chaperone, Hsc70, from the eurythermal marine goby Gillichthys mirabilis. Using in vitro assays, we measured the intrinsic activity, unfolded-protein-stimulated activity, temperature sensitivity and heat stability of the ATPase activity of native Hsc70 purified from G. mirabilis white muscle. Similar to other chaperones in the 70kDa heat-shock protein family, G. mirabilis Hsc70 exhibited a low intrinsic ATPase activity that was stimulated in vitro by the addition of unfolded protein. Across the environmentally relevant temperature range (10-35 degrees C), the ATPase activity of G. mirabilis Hsc70 displayed differential thermal sensitivity, with the greatest sensitivity occurring between 10 and 15 degrees C and the least sensitivity between 15 and 25 degrees C. In addition, the activity of Hsc70 was not significantly different between the unstimulated and unfolded-protein-stimulated treatments, suggesting that the ATPase activity and the peptide-binding domain of Hsc70 have similar thermal sensitivities in vitro. Finally, the thermal stability of Hsc70 ATPase activity greatly exceeded environmental temperatures for G. mirabilis, with activity up to 62.5 degrees C. Overall, the biochemical characterization of the ATPase activity suggests that, although Hsc70 is not an extraordinarily thermally stable protein, it is capable of protein chaperoning cycles even at the extremes of environmental temperatures encountered by G. mirabilis in nature.

Adenosine Triphosphatases↗