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At least 145 records · Page 8Linked to original sources
PubMed1989

Structure and function of a menaquinone involved in electron transport in membranes of Clostridium thermoautotrophicum and Clostridium thermoaceticum.

Clostridium thermoaceticum and Clostridium thermoautotrophicum contain the same menaquinone. Its structure, determined by thin-layer chromatography, UV absorption spectroscopy, mass spectrometry, and nuclear magnetic resonance spectroscopy, was found to be MK-7 (2-methyl-3-heptaprenyl-1,4-naphthoquinone). The menaquinone is located in the cytoplasmic membranes and is involved in redox reactions of two b-type cytochromes present in the clostridia. These reactions were studied with right-side-out membranes prepared from C. thermoautotrophicum by using CO as an electron donor. In intact membranes, both cytochromes were reduced, whereas after inactivation of the menaquinone by exposure of the membranes to UV irradiation, reduction of the low-potential cytochrome (Eo', -200 mV) but not of the high-potential cytochrome (Eo', -48 mV) occurred. The reduction of the high-potential cytochrome in UV-irradiated membranes was restored following the addition of oxidized menaquinone and with an excess of CO. The addition of oxidized menaquinone to reduced membranes resulted initially in a preferential oxidation of the low-potential cytochrome. The results obtained indicate that the menaquinone acts between the two b-type cytochromes in an electron transport chain.

Cell Membrane↗
PubMed1989

Ammonia assimilation pathways in nitrogen-fixing Clostridium kluyverii and Clostridium butyricum.

Pathways of ammonia assimilation into glutamic acid were investigated in ammonia-grown and N2-fixing Clostridium kluyverii and Clostridium butyricum by measuring the specific activities of glutamate dehydrogenase, glutamine synthetase, and glutamate synthase. C. kluyverii had NADPH-glutamate dehydrogenase with a Km of 12.0 mM for NH4+. The glutamate dehydrogenase pathway played an important role in ammonia assimilation in ammonia-grown cells but was found to play a minor role relative to that of the glutamine synthetase/NADPH-glutamate synthase pathway in nitrogen-fixing cells when the intracellular NH4+ concentration and the low affinity of the enzyme for NH4+ were taken into account. In C. butyricum grown on glucose-salt medium with ammonia or N2 as the nitrogen source, glutamate dehydrogenase activity was undetectable, and the glutamine synthetase/NADH-glutamate synthase pathway was the predominant pathway of ammonia assimilation. Under these growth conditions, C. butyricum also lacked the activity of glucose-6-phosphate dehydrogenase, which catalyzes the regeneration of NADPH from NADP+. However, high activities of glucose-6-phosphate dehydrogenase as well as of NADPH-glutamate dehydrogenase with a Km of 2.8 mM for NH4+ were present in C. butyricum after growth on complex nitrogen and carbon sources. The ammonia-assimilating pathway of N2-fixing C. butyricum, which differs from that of the previously studied Bacillus polymyxa and Bacillus macerans, is discussed in relation to possible effects of the availability of ATP and of NADPH on ammonia-assimilating pathways.

Ammonia↗
PubMed1995

Physical map of the Clostridium beijerinckii (formerly Clostridium acetobutylicum) NCIMB 8052 chromosome.

A combined physical and genetic map of the single, circular, 6.7-Mbp chromosome of the NCIMB 8052 strain of Clostridium beijerinckii (formerly Clostridium acetobutylicum) has been constructed by using a combination of cloned DNA fragments as hybridization probes and a bank of strains harboring insertions of the conjugative transposon Tn1545. The positions of 81 restriction endonuclease cleavage sites and 32 genes have been determined. Eight genes concerned with solventogenic fermentation are found at three different locations. The chromosome contains at least 13 rrn operons, 11 of which have been located on the map. Their transcriptional orientation diverges from the presumed location of the replication origin.

Chromosome Mapping↗
PubMed1996

Effect of nitrate on the autotrophic metabolism of the acetogens Clostridium thermoautotrophicum and Clostridium thermoaceticum.

Although nitrate stimulated the capacity of Clostridium thermoautotrophicum and Clostridium thermoaceticum to oxidize (utilize) substrates under heterotrophic conditions, it inhibited autotrophic H2-CO2-dependent growth. Under basal medium conditions, nitrate was also inhibitory to the use of one-carbon substrates (i.e., CO, formate, methanol, or the O-methyl groups of vanillate or syringate) as sole carbon energy sources. This inhibitory effect of nitrate was bypassed when both O-methyl groups and CO were provided concomitantly; H2-CO2 did not replace CO. These results indicated that nitrate blocked the reduction of CO2 to the methyl and carbonyl levels. On the basis of the inability of acetogenic cells (i.e., cells cultivated without nitrate) to consume or reduce nitrate in resting-cell assays, the capacity to dissimilate nitrate was not constitutive. Nitrate had no appreciable effect on the specific activities of enzymes central to the acetyl-coenzyme A (CoA) pathway. However, membranes obtained from cells cultivated under nitrate-dissimilating conditions were deficient in the b-type cytochrome that was typical of membranes from acetogenic cells, i.e., cells dependent upon the synthesis of acetate for the conservation of energy. Collectively, these findings indicated that (i) C. thermoautotrophicum and C. thermoaceticum cannot engage the carbon-fixing capacities of the acetyl-CoA pathway in the presence of nitrate and (ii) the nitrate block on the acetyl-CoA pathway occurs via an alteration in electron transport.

Acetyl Coenzyme A↗
PubMed2006

Comparative analysis of prevalence, risk factors, and molecular epidemiology of antibiotic-associated diarrhea due to Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus.

We prospectively studied the comparative epidemiology and risk factors for Clostridium difficile, Clostridium perfringens, and Staphylococcus aureus antibiotic-associated diarrhea (AAD). Four thousand six hundred fifty-nine inpatient fecal specimens (11 months) were tested for C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus by Vero cell assay, enzyme-linked immunosorbent assay, and growth on fresh blood agar, respectively. Two distinct age-, sex-, and location-matched control patient groups were used for multivariate logistic regression risk factor analyses: symptomatic patients who were AAD pathogen negative and asymptomatic patients with histories of recent antimicrobial therapy. All AAD pathogen isolates were DNA fingerprinted. In AAD cases, the prevalences of C. difficile cytotoxin, C. perfringens enterotoxin, and S. aureus were 12.7%, 3.3%, and 0.2%, respectively (15.8% overall). Age of >70 years was a common risk factor. Other risk factors for infective AAD and C. difficile AAD included length of hospital stay and use of feeding tubes (length of stay odds ratios [OR], 1.017 and 1.012; feeding tube OR, 1.864 and 2.808). Female gender and use of antacids were significantly associated with increased risk of C. perfringens AAD (OR, 2.08 and 2.789, respectively), but unlike what was found for C. difficile AAD, specific antibiotic classes were not associated with increased risk. A limited number of genotypes caused the majority of C. difficile and C. perfringens AAD cases. Similar to what was found for C. difficile AAD, there was epidemiological evidence of C. perfringens AAD case clustering and reinfection due to different strains. C. difficile AAD was approximately 4 and 60 times more common than C. perfringens AAD and S. aureus AAD, respectively. Risk factors for these AAD pathogens differed, highlighting the need to define specific control measures. There is evidence of nosocomial transmission in cases of C. perfringens AAD.

Adolescent↗
PubMed1979

Cultures for Clostridium difficile in stools containing a cytotoxin neutralized by Clostridium sordellii antitoxin.

Stools from patients with antibiotic-associated diarrhea or colitis were cultured to detect the presence of Clostridium difficile. All specimens contained a cytotoxin which was neutralized by Clostridium sordellii antitoxin. Initial testing employed several methods with comparative merits in recovering this organism. These included the use of nonselective media, antibiotic-incorporated media, alcohol shock, and paracresol-containing broth. Optimal results were achieved with primary plating of serial dilutions onto a selective agar containing cycloserine and cefoxitin. This technique was then employed in a large number of specimens. The overall results showed that C. difficile was recovered in specimens from 71 of 73 patients. All isolates of C. difficile produced a cytotoxin which was neutralized by C. sordellii antitoxin in vitro. These results verify the utility of this medium and support the concept that C. difficile accounts for the cytotoxin found in stools in nearly all cases.

Antitoxins↗
PubMed1997

Purification and characterization of konjac glucomannan degrading enzyme from anaerobic human intestinal bacterium, Clostridium butyricum-Clostridium beijerinckii group.

Konjac glucomannan degrading enzyme was purified to homogeneity from the culture broth of an anaerobic human intestinal bacterium, Clostridium butyricum-Clostridium beijerinckii group. The enzyme was composed of a single polypeptide chain with a molecular weight of 50,000-53,000. The enzyme was an endo-beta-mannanase that acted specifically on the polysaccharides such as konjac glucomannan and coffee mannan, producing exclusively their smaller oligosaccharides and the monosaccharides. The optimal pH of the enzyme for the hydrolysis of konjac glucomannan was around 7-8 and the enzyme was stable in rather alkaline pH range of 8-10. The enzyme reaction was activated by the addition of CaCl2 and dithiothreitol. It was suggested that the enzyme might contribute to the decomposition of konjac glucomannan in human digestive tract.

Calcium Chloride↗
PubMed1975

The use of 13C nuclear magnetic resonance of aromatic amino acid residues to determine the midpoint oxidation-reduction potential of each iron-sulfur cluster of Clostridium acidi-urici and Clostridium pasteurianum ferredoxins.

13C NMR of the aromatic residues of Clostridium acidi-urici [Phe2]ferredoxin (a chemically modified ferredoxin in which a phenylalanyl residue replaces a tyrosyl residue) and Clostridium pasteurianum ferredoxin permits one to distinguish and probe each iron-sulfur (Fe7S7) cluster neighboring the aromatic residues within each protein. This is because the ring carbon resonance shifts of the phenylalanyl and tyrosyl residues can be distinguished. The 13C NMR results suggest that the midpoint oxidation-reduction potentials of the two Fe4S4 clusters in C. pasteurianum and C. acidi-urici ferredoxin differ by 10 plus or minus 5 mv and smaller than mv, respectively. 13C NMR of an equilibrium mixture of methyl viologen-reduced C. acidi-urici and C. pasteurianum ferredoxin shows that the protein midpoint oxidation-reduction potential of C. acidi-urici ferredoxin is 47 plus or minus 10 mv lower than that of C. pasteurianum ferredoxin. We attribute the differences in cluster and protein midpoint oxidation-reduction potentials to differences in protein structure.

Carbon Isotopes↗
PubMed1991

Phosphorylation of cellular proteins in response to treatment with Clostridium difficile toxin B and Clostridium sordellii toxin L.

Toxin B from Clostridium difficile induces typical morphological changes of cultured cells consisting of rounding up and arborization, which are associated with a dramatic disruption of microfilaments. In this study, we show that toxin L, a cytotoxin produced by bacterial strain Clostridium sordellii, has similar effects on cultured cells including the redistribution of F-actin and of the adhesion plaque protein vinculin. It has been assumed that the mechanisms involved in cytopathic effects of toxin B are related to the function of an unidentified component that regulates the organization of the actin cytoskeleton. We demonstrate that the treatment of cultured astrocytes with toxin B or toxin L alters the incorporation of inorganic phosphate into several proteins. Immunoblot analysis revealed that one of these proteins is tropomyosin. Since tropomyosin stabilizes microfilaments and inhibits the severing activity of gelsolin, the toxin-induced phosphorylation may counteract this inhibition resulting in severing of microfilaments and capping of short filaments. A decrease in the radioactivity associated with intermediate filament protein vimentin was also detected using a monoclonal antibody which specifically recognizes a phosphorylated epitope of vimentin. Since vimentin is an in vivo substrate for various protein kinases, these data are in favor of broad effects of these toxins. Direct measurement of protein kinase C in cells exposed to toxin B or to toxin L did not reveal a significant change in protein kinase C activity. Furthermore, treatments with toxins do not increase cAMP levels, suggesting that toxins do not activate protein kinase A. Although further studies are required to determine the primary target site for the clostridial cytotoxin B and L, our results show that they provoke the alteration in the phosphorylation of cellular proteins.

Actin Cytoskeleton↗
PubMed1991

Proposed scheme for isolation and identification of Clostridium perfringens and Clostridium perfringens-like organisms.

The properties of 220 strains of Clostridium perfringens and Clostridium perfringens-like organisms were studied. A scheme was designed for the identification of these strains. The scheme was based on the presence/or absence of lecithinase enzyme, synergestic haemolysis with Streptococcus group B toxin, their inhibition with appropriate antisera and reaction in the lactose gelatin nitrate motility test (LGNM) with the fermentation of a few sugars.

Animals↗
PubMed1990

Characterization of the ADP-ribosylation of actin by Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin.

Clostridium botulinum C2 toxin and Clostridium perfringens iota toxin belong to a novel family of actin ADP-ribosylating toxins. ADP-ribosylation of actin inhibits actin polymerization and G-actin-associated ATPase activity. The ADP-form of actin is ADP-ribosylated at a higher rate than actin with bound ATP. ADP-ribosylation of actin is reversible, a reaction, which is accompanied by reconstitution of actin ATPase activity.

Actins↗
PubMed1989

Note on an association of Clostridium novyi type A and Clostridium sordellii with a case of gas-gangrene in a Zebu cow.

A case of gas-gangrene myositis on a Zebu cow with association of Clostridium novyi type A and Clostridium sordellii is described. The occurrence of both organisms in the same lesion has been rarely reported and differential diagnosis with blackleg is difficult in the absence of bacteriological tests. An iatrogenic cause cannot be overruled as routine mass vaccination against blackleg are practiced in the area with possible introduction of spores through infection material. Full recovery occurred after four days intramuscular Terramycin shot.

Animals↗
PubMed1988

Selenium-dependent glycine reductase: differences in physicochemical properties and biological activities of selenoprotein A components isolated from Clostridium sticklandii and Clostridium purinolyticum.

The selenoprotein A component of the glycine reductase complex of Clostridium sticklandii was shown to differ in certain properties from the selenoprotein A produced by a purine-fermenting organism, Clostridium purinolyticum. Both proteins contain one selenocysteine and two cysteine residues.

Amino Acid Oxidoreductases↗
PubMed1986

The tetragonal surface layer of Clostridium aceticum: three-dimensional structure and comparison with the hexagonal layer of Clostridium thermohydrosulfuricum.

The regular surface layer (S-layer) of Clostridium aceticum has been isolated and the three-dimensional structure determined to a resolution of 2.0 nm from tilt series of negatively stained preparations. It has tetragonal symmetry with a lattice constant of 12 nm and a thickness of 6 nm; there are probably 4 protein monomers per unit cell. A large proportion of the protein is concentrated in massive "cores" at the major four-fold axes which are situated towards the inner surface of the layer. From these cores, delicate arms extend towards the minor four-fold axes, where secondary connectivity is established near the exterior surface. When viewed from the outside, each of the cores appears to have a large central depression, rather than a true "pore". Since this general pattern of mass distribution is shared by the hexagonal S-layer of Clostridium thermohydrosulfuricum, some consideration has been given to the possible evolutionary steps leading to changes in symmetry. From modelling experiments, it is evident that the change from four-fold to six-fold symmetry in this instance could be accomplished simply by the loss of a structural "domain" from the protomer.

Bacterial Proteins↗
PubMed1984

Mode of action of steroid desmolase and reductases synthesized by Clostridium "scindens" (formerly Clostridium strain 19).

A recently isolated hitherto unknown Clostridium from human feces, designated Clostridium "scindens" (formerly strain 19), synthesizes at least two enzymes active on the side-chain of the steroid molecule and two enzymes active on the hydroxyl groups of the 7-position of bile acids. Steroid desmolase, responsible for side-chain cleavage of corticoids, and 20 alpha-hydroxysteroid dehydrogenase have not been detected in any other bacterial species of the resident colonic flora. Steroid desmolase is Eh-dependent (optimum ca. -130 mV), requires a hydroxy group at C-17, and preferably an alpha-ketol group in the side-chain; an alpha-hydroxy group at C-20 reduces and a beta-hydroxy group at C-20 prevents side-chain cleavage. With suitable substrates, the yield of C-19 steroids is proportional to the bacterial multiplication rate. 20 alpha-Hydroxysteroid dehydrogenase (20 alpha-HSDH) is also Eh-dependent (optimum ca. -300 mV) and reduces the C-20 keto function to an alpha-hydroxy group, regardless of the presence or absence of a hydroxy group at C-17. 7 alpha-Dehydroxylase metabolizes cholic and chenodeoxycholic acid, while 7 beta-hydroxysteroid dehydrogenase acts upon ursodeoxycholic acid. The latter two enzymes are not specific for C. scindens.

Bile Acids and Salts↗
PubMed1978

Assignment of the cysteinyl 13C nuclear magnetic resonances and comparison of other aliphatic amino acid resonances of Clostridium acidi-urici, Clostridium pasteurianum, and Peptococcus aerogenes ferredoxins.

13C NMR spectra of Clostridium acidi-urici, Clostridium pasteurianum, and Peptococcus aerogenes ferredoxins show that some 13C resonances of the aliphatic amino acid residues are shifted significantly from their corresponding resonance positions in the spectra of model polypeptides or apoferredoxin. Thirteen 13C resonances are shifted into the 80- to 120-ppm (from CS2) region, and have been assigned to the cysteinyl alpha and beta carbon atoms. The remaining shifted resonances in the 120- to 190-ppm region are tentatively assigned to amino acid residues that may be close to [4Fe-4S] clusters of the oxidized and reduced ferredoxins. The similarity in the shift pattern of the corresponding 13C resonances of the cysteinyl alpha and beta carbon atoms in the three ferredoxins studied suggests that the three-dimensional amino acid environments of the corresponding [4Fe-4S] clusters in each protein are similar.

Amino Acids↗
PubMed1997

Species-specificity of the cohesin-dockerin interaction between Clostridium thermocellum and Clostridium cellulolyticum: prediction of specificity determinants of the dockerin domain.

The cross-species specificity of the cohesin-dockerin interaction, which defines the incorporation of the enzymatic subunits into the cellulosome complex, has been investigated. Cohesin-containing segments from the cellulosomes of two different species, Clostridium thermocellum and Clostridium cellulolyticum, were allowed to interact with cellulosomal (dockerin-containing) enzymes from each species. In both cases, the cohesin domain of one bacterium interacted with enzymes from its own cellulosome in a calcium-dependent manner, but the same cohesin failed to recognize enzymes from the other species. Thus, in the case of these two bacteria, the cohesin-dockerin interaction seems to be species-specific. Based on intra- and cross-species sequence comparisons among the different dockerins together with their known specificities, we tender a prediction as to the amino-acid residues critical to recognition of the cohesins. The suspected residues were narrowed down to only four, which comprise a repeated pair located within the calcium-binding motif of two duplicated sequences, characteristic of the dockerin domain. According to the proposed model, these four residues do not participate in the binding of calcium per se; instead, they appear to serve as recognition codes in promoting interaction with the cohesin surface.

Amino Acid Sequence↗
PubMed1998

Molecular characterization of type E Clostridium botulinum and comparison to other types of Clostridium botulinum.

Determination of nucleotide sequence upstream to the neurotoxin binding protein (NBP) gene of type E Clostridium botulinum has revealed an open reading frame whose stop codon is only 18 bp apart from the start codon of the NBP gene. Amino acid sequence derived from the corresponding nucleotide sequence suggested the existence of the open reading frame as a 47.8 kDa protein (P-48). Protein data bank search revealed that the 47.8 kDa protein has 80% sequence identity to P-47 of type F C. botulinum. The gene organization of type E. Clostridium botulinum was predicted and compared to other types of C. botulinum. In type E C. botulinum, genes for the P-48, the neurotoxin binding protein and the neurotoxin form an operon which was similar to that of type F C. botulinum. However, type E C. botulinum has a P-18 gene instead of P-21 gene observed in type F C. botulinum, both located upstream to their respective P-48/P-47 gene.

Amino Acid Sequence↗