Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “PEPTIDASE”

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 1,117 records · Page 62Linked to original sources
PubMed1997

Intranasal immunization with C5a peptidase prevents nasopharyngeal colonization of mice by the group A Streptococcus.

Early inflammatory events are initiated by phased production of C5a and interleukin-8 in tissue. Most serotypes of group A streptococci express a surface-bound peptidase (SCPA) which specifically cleaves mouse and human C5a chemotaxins. This study investigates the impact of SCPA on colonization of the nasopharyngeal mucosa of mice and evaluates its potential to induce protective immunity. Two strains, serotypes M6 and M49, which contain insertion and deletion mutations in the SCPA gene (scpA) and represent the two major subdivisions of group A streptococci, were characterized and compared in a mouse intranasal infection model. In this model, SCPA mutants were more rapidly cleared from the nasopharynges of inoculated mice compared with wild-type strains. A 2,908-bp fragment of scpA49 gene, obtained by PCR, was ligated to the expression vector pGEX-4T-1 and expressed in Escherichia coli. The affinity-purified deltaSCPA49 protein proved to be highly immunogenic in mice and rabbits. Although the purified deltaSCPA49 immunogen lacked enzymatic activity, it induced high titers of rabbit antibodies which were able to neutralize peptidase activity associated with M1, M6, M12, and M49 streptococci in vitro. This result confirmed that antipeptidase antibodies lack serotype specificity. Intranasal immunization of mice with the deleted form of the SCPA49 protein stimulated significant levels of specific salivary secretory immunoglobulin A (IgA) and serum IgG antibodies and reduced the potential of wild-type M1, M2, M6, M11, and M49 streptococci to colonize. These experiments suggest a new approach to vaccine development for prevention of streptococcal pharyngitis.

Adhesins, Bacterial↗
PubMed2002

Identification of novel adhesins from Group B streptococci by use of phage display reveals that C5a peptidase mediates fibronectin binding.

Group B streptococci (GBS) are a major cause of pneumonia, sepsis, and meningitis in newborns and infants. GBS initiate infection of the lung by colonizing mucosal surfaces of the respiratory tract; adherence of the bacteria to host cells is presumed to be the initial step in and prerequisite for successful colonization (G. S. Tamura, J. M. Kuypers, S. Smith, H. Raff, and C. E. Rubens, Infect. Immun. 62:2450-2458, 1994). We have performed a genome-wide screen to identify novel genes of GBS that mediate adherence to fibronectin. A shotgun phage display library was constructed from chromosomal DNA of a serotype Ia GBS strain and affinity selected on immobilized fibronectin. DNA sequence analysis of different clones identified 19 genes with homology to known bacterial adhesin genes, virulence genes, genes involved in transport or metabolic processes, and genes with yet-unknown function. One of the isolated phagemid clones showed significant homology to the gene (scpB) for the GBS C5a peptidase, a surface-associated serine protease that specifically cleaves the complement component C5a, a chemotaxin for polymorphonuclear leukocytes. In this work we have demonstrated that affinity-purified recombinant ScpB and a peptide ScpB fragment (ScpB-PDF), similar to the peptide identified in the phagemid, bound fibronectin in a concentration-dependent manner. Adherence assays to fibronectin were performed, comparing an isogenic scpB mutant to the wild-type strain. Approximately 50% less binding was observed with the mutant than with the wild-type strain. The mutant phenotype could be fully restored by in trans complementation of the mutant with the cloned wild-type scpB gene, providing further evidence for the role of ScpB in fibronectin adherence. Our results suggest that C5a peptidase is a bifunctional protein, which enzymatically cleaves C5a and mediates adherence to fibronectin. Since binding of fibronectin has been implicated in attachment and invasion of eukaryotic cells by streptococci, our results may imply a second important role for this surface protein in the pathogenesis of GBS infections.

Adhesins, Bacterial↗
PubMed1978

Peptide utilization in Pseudomonas aeruginosa: evidence for membrane-associated peptidase.

A methionine auxotroph of Pseudomonas aeruginosa grew on methionine-containing peptides as a source of the required amino acid. Amino-terminus-blocked peptides would not serve as growth substrates, despite the fact that peptidases active on these blocked peptides were readily detectable in cell extracts. No evidence was found for extracellular enzymes capable of degrading the oligopeptides investigated. The degradative enzymes were not found in the periplasmic space of the cellular envelope. A high proportion of cellular peptidase activity was associated with the particulate (membrane) fraction of the cell lysate.

Bacteriolysis↗
PubMed1983

Overproduction of Salmonella typhimurium peptidase T.

Pseudorevertants able to use L-leucyl-L-leucyl-L-leucine as a leucine source have been isolated from a Salmonella typhimurium strain carrying stable (nonreverting) mutations in pepN, pepA, and pepB. These strains carry mutations at a locus pto (peptidase T overproducer) tightly linked to pepT that cause an elevated expression of the tripeptidase peptidase T. An F' episome carrying the pto and pepT loci has been constructed and used to show that the pto mutations are cis dominant. Expression of beta-galactosidase from a Mu d1(Apr lac) insertion in pepT is increased by pto mutations. The pto mutations, therefore, define a site affecting the transcription of pepT.

Aminopeptidases↗
PubMed1984

Mapping of the lipoprotein signal peptidase gene (lsp).

A pBR322 plasmid which contains a fragment of Escherichia coli DNA encoding the lipoprotein signal peptidase gene was used to transform Hfr polA1 strains. Ampr transformants were used as donors in conjugation experiments, and the location of the plasmid amp gene adjacent to the chromosomal lsp gene was determined to be near the thr ara loci of the E. coli chromosome. P1 transduction experiments established that the location of the lsp gene is closely linked to that of dapB , at 0.5 to 0.6 min on the E. coli genetic map. The position of the lsp gene was further determined to be between ileS and dapB by complementation analysis of an E. coli mutant showing temperature-sensitive prolipoprotein signal peptidase activity.

Chromosome Mapping↗
PubMed1989

Conditionally lethal amber mutations in the leader peptidase gene of Escherichia coli.

The lep gene of Escherichia coli encodes the leader peptidase which cleaves amino-terminal leader sequences of secreted proteins. To facilitate the study of structure-function relationships of the leader peptidase, 22 amber mutations in lep were isolated by localized mutagenesis. These amber mutants grew at 32 degrees C but not at 42 degrees C in the presence of a temperature-sensitive amber suppressor. Most of them were lethal under sup0 conditions. However, one amber mutant, the lep-9 mutant, exhibited temperature-sensitive growth in the sup0 strain, indicating that the amber fragment is active at 32 degrees C but not at 42 degrees C. Protein precursors of the maltose-binding protein and OmpA accumulate strikingly in the lep-9 mutant.

Chromosome Mapping↗
PubMed1990

Nucleotide sequence of the Pseudomonas fluorescens signal peptidase II gene (lsp) and flanking genes.

The lsp gene encoding prolipoprotein signal peptidase (signal peptidase II) is organized into an operon consisting of ileS and three open reading frames, designated genes x, orf149, and orf316 in both Escherichia coli and Enterobacter aerogenes. A plasmid, pBROC128, containing a 5.8-kb fragment of Pseudomonas fluorescens DNA was found to confer pseudomonic acid resistance on E. coli host cells and to contain the structural gene of ileS from P. fluorescens. In addition, E. coli strains carrying pBROC128 exhibited increased globomycin resistance. This indicated that the P. fluorescens lsp gene was present on the plasmid. The nucleotide sequences of the P. fluorescens lsp gene and of its flanking regions were determined. Comparison of the nucleotide sequences of the lsp genes in E. coli and P. fluorescens revealed two highly conserved domains in this enzyme. Furthermore, the five genes which constitute an operon in E. coli and Enterobacter aerogenes were found in P. fluorescens in the same order as in the first two species.

Amino Acid Sequence↗
PubMed1996

Membrane insertion of the F-pilin subunit is Sec independent but requires leader peptidase B and the proton motive force.

F pilin is the subunit required for the assembly of conjugative pili on the cell surface of Escherichia coli carrying the F plasmid. Maturation of the F-pilin precursor, propilin, involves three F plasmid transfer products: TraA, the propilin precursor; TraQ, which promotes efficient propilin processing; and TraX, which is required for acetylation of the amino terminus of the 7-kDa pilin polypeptide. The mature pilin begins at amino acid 52 of the TraA propilin sequence. We performed experiments to determine the involvement of host cell factors in propilin maturation. At the nonpermissive temperature in a LepBts (leader peptidase B) host, propilin processing was inhibited. Furthermore, under these conditions, only full-length precursor was observed, suggesting that LepB is responsible for the removal of the entire propilin leader peptide. Using propilin processing as a measure of propilin insertion into the plasma membrane, we found that inhibition or depletion of SecA and SecY does not affect propilin maturation. Addition of a general membrane perturbant such as ethanol also had no effect. However, dissipation of the proton motive force did cause a marked inhibition of propilin processing, indicating that membrane insertion requires this energy source. We propose that propilin insertion in the plasma membrane proceeds independently of the SecA-SecY secretion machinery but requires the proton motive force. These results present a model whereby propilin insertion leads to processing by leader peptidase B to generate the 7-kDa peptide, which is then acetylated in the presence of TraX.

Adenosine Triphosphatases↗
PubMed2000

Posttranslational processing of Methanococcus voltae preflagellin by preflagellin peptidases of M. voltae and other methanogens.

Methanococcus voltae is a mesophilic archaeon with flagella composed of flagellins that are initially made with 11- or 12-amino-acid leader peptides that are cleaved prior to incorporation of the flagellin into the growing filament. Preflagellin peptidase activity was demonstrated in immunoblotting experiments with flagellin antibody to detect unprocessed and processed flagellin subunits. Escherichia coli membranes containing the expressed M. voltae preflagellin (as the substrate) were combined in vitro with methanogen membranes (as the enzyme source). Correct processing of the preflagellin to the mature flagellin was also shown directly by comparison of the N-terminal sequences of the two flagellin species. M. voltae preflagellin peptidase activity was optimal at 37 degrees C and pH 8.5 and in the presence of 0.4 M KCl with 0.25% (vol/vol) Triton X-100.

Electrophoresis, Polyacrylamide Gel↗
PubMed2001

The PDZ domain of the SpoIVB serine peptidase facilitates multiple functions.

During spore formation in Bacillus subtilis, the SpoIVB protein is a critical component of the sigma(K) regulatory checkpoint. SpoIVB has been shown to be a serine peptidase that is synthesized in the spore chamber and which self-cleaves, releasing active forms. These forms can signal proteolytic processing of the transcription factor sigma(K) in the outer mother cell chamber of the sporulating cell. This forms the basis of the sigma(K) checkpoint and ensures accurate sigma(K)-controlled gene expression. SpoIVB has also been shown to activate a second distinct process, termed the second function, which is essential for the formation of heat-resistant spores. In addition to the serine peptidase domain, SpoIVB contains a PDZ domain. We have altered a number of conserved residues in the PDZ domain by site-directed mutagenesis and assayed the sporulation phenotype and signaling properties of mutant SpoIVB proteins. Our work has revealed that the SpoIVB PDZ domain could be used for up to four distinct processes, (i) targeting of itself for trans proteolysis, (ii) binding to the protease inhibitor BofC, (iii) signaling of pro-sigma(K) processing, and (iv) signaling of the second function of SpoIVB.

Alleles↗
PubMed2002

SipY Is the Streptomyces lividans type I signal peptidase exerting a major effect on protein secretion.

Most bacteria contain one type I signal peptidase (SPase) for cleavage of signal peptides from secreted proteins. The developmental complex bacterium Streptomyces lividans has the ability to produce and secrete a significant amount of proteins and has four different type I signal peptidases genes (sipW, sipX, sipY, and sipZ) unusually clustered in its chromosome. Functional analysis of the four SPases was carried out by phenotypical and molecular characterization of the different individual sip mutants. None of the sip genes seemed to be essential for bacterial growth. Analysis of total extracellular proteins indicated that SipY is likely to be the major S. lividans SPase, since the sipY mutant strain is highly deficient in overall protein secretion and extracellular protease production, showing a delayed sporulation phenotype when cultured in solid medium.

Bacterial Proteins↗
PubMed2005

Inactivation of a predicted leader peptidase prevents photoautotrophic growth of Synechocystis sp. strain PCC 6803.

To establish the role of the two putative type I leader peptidases (LepB1 and LepB2) encoded in the genome of the cyanobacterium Synechocystis sp. strain PCC 6803, we generated independent knockout mutants for both genes by introducing kanamycin resistance cassettes into the two open reading frames (sll0716 [lepB1] and slr1377 [lepB2], respectively). Although the insertion was successful in both instances, it was not possible to select homozygous mutant cells for lepB2, suggesting that the function of this gene is essential for cell viability. In contrast, LepB1 is apparently essential only for photoautotrophic growth, because homozygous lepB1::Km(r) cells could be propagated under heterotrophic conditions. They were even capable to some extent of photosynthetic oxygen evolution. However, the photosynthetic activity decreased gradually with extended incubation in the light and was particularly affected by high light intensities. Both features were indicative of photooxidative damage, which was probably caused by inefficient replacement of damaged components of the photosynthetic machinery due to the lack of a leader peptidase removing the signal peptides from photosynthetic precursor proteins. Indeed, processing of the PsbO precursor polypeptide to the corresponding mature protein was significantly affected in the mutant, and reduced amounts of other proteins that are synthesized as precursors with signal peptides accumulated in the cells. These results strongly suggest that LepB1 is important for removal of the signal peptides after membrane transport of the components of the photosynthetic machinery, which in turn is a prerequisite for the biogenesis of a functional photosynthetic electron transport chain.

Bacterial Proteins↗
PubMed2006

Active-site residues in the type IV prepilin peptidase homologue PibD from the archaeon Sulfolobus solfataricus.

Archaeal preflagellin peptidases and bacterial type IV prepilin peptidases belong to a family of aspartic acid proteases that cleave the leader peptides of precursor proteins with type IV prepilin signal sequences. The substrate repertoire of PibD from the crenarchaeon Sulfolobus solfataricus is unusually diverse. In addition to flagellin, PibD cleaves three sugar-binding proteins unique to this species and a number of proteins with unknown function. Here we demonstrate that PibD contains two aspartic acid residues that are essential for cleavage activity. An additional pair of aspartic acids in a large cytoplasmic loop is also important for function and is possibly involved in leader peptide recognition. Combining the results of transmembrane segment predictions and cysteine-labeling experiments, we suggest a membrane topology model for PibD with the active-site aspartic acid residues exposed to the cytosol.

Archaeal Proteins↗
PubMed1989

Mutations in the signal sequence of prepro-alpha-factor inhibit both translocation into the endoplasmic reticulum and processing by signal peptidase in yeast cells.

The effects of five single-amino-acid substitution mutations within the signal sequence of yeast prepro-alpha-factor were tested in yeast cells. After short pulse-labelings, virtually all of the alpha-factor precursor proteins from a wild-type gene were glycosylated and processed by signal peptidase. In contrast, the signal sequence mutations resulted in the accumulation of mostly unglycosylated prepro-alpha-factor after a short labeling interval, indicating a defect in translocation of the protein into the endoplasmic reticulum. Confirming this interpretation, unglycosylated mutant prepro-alpha-factor in cell extracts was sensitive to proteinase K and therefore in a cytosolic location. The signal sequence mutations reduced the rate of translocation into the endoplasmic reticulum by as much as 25-fold or more. In at least one case, mutant prepro-alpha-factor molecules were translocated almost entirely posttranslationally. Four of the five mutations also reduced the rate of proteolytic processing by signal peptidase in vivo, even though the signal peptide alterations are not located near the cleavage site. This study demonstrates that a single-amino-acid substitution mutation within a eucaryotic signal peptide can affect both translocation and proteolytic processing in vivo and may indicate that the recognition sequences for translocation and processing overlap within the signal peptide.

Acetylglucosaminidase↗
PubMed1981

Isozymes of Culex p. fatigans. III. Genetics of leucine-amino-peptidase.

Zymograms of leucine-amino-peptidase (LAP) of the mosquito Culex pipiens fatigans Wiedemann (C. p. quinquefasciatus) showed 20 isozyme bands in the fourth instar larvae, 13 in the pupae and 3 in the older adults. Homozygous strains of Lap-1F (Fast) and Lap-1S (Slow) were isolated and linkage studies carried out. Lap-1F and Lap-1S allozymes act as codominant alleles, are sex linked and are located in linkage group I. The gene sequence is e-M-mar-Lap-1 (eye-gap, maroon-eye, leucine-amino-peptidase-1), and the linkage distances in the M-mar and mar-Lap-1 segments are 22.0 and 10.5, respectively. Gene frequency analysis of natural populations from Brazil and Pakistan showed the S allele was more frequent in the Brazilian populations whereas F was more frequent in the Pakistani populations. Fixation of F allele had occurred in two Pakistani populations.

Alleles↗
PubMed1988

Regulatory signals for intestinal amino acid transporters and peptidases.

Dietary protein ultimately regulates many processes involved in protein digestion, but it is often unclear whether proteins themselves, peptides, or amino acids (AAs) are the proximate regulatory signal. Hence we compared several processes involved in protein digestion in mice adapted to one of three rations, identical except for containing 54% of either casein, a partial hydrolysate of casein, or a free AA mixture simulating a complete hydrolysate of casein. We measured brush-border uptakes of seven AAs that variously serve as substrates for four AA transporters, and brush-border and cytosolic activities of four peptidases. The three rations yielded essentially the same AA uptake rates. Peptidase activities tended to be lower on the AA ration than on the protein ration. In other studies, all three rations yielded the same rates of brush-border peptide uptake; protein is only modestly more effective than AAs at inducing synthesis of pancreatic proteases; and, depending on the animal species, protein is either much less or much more effective than AAs at stimulating release of cholecystokinin and hence of pancreatic enzymes. Thus the regulators of each process involved in protein digestion are not necessarily that process's substrate. We call attention to other cases in which the functional significance of regulatory signals remains to be understood.

Amino Acids↗
PubMed1990

Inhibitors of peptidases: how they influence the biological activities of substance P, neurokinins, bradykinin and angiotensin in guinea pig, hamster and rat urinary bladders.

Neurokinins, bradykinin and angiotensins were tested in isolated urinary bladder of the guinea pig, the hamster and the rat, in the absence and in presence of a variety of peptidase inhibitors in order to establish if peptide degradation interferes with the bladder contractions elicited by the three types of peptides. Indeed, the effects of neurokinins, bradykinin and angiotensin I in the guinea pig bladder were significantly enhanced by captopril (4.6 x 10(-6) mol/l), chymostatin (1 mg/l), phosphoramidon (4.6 x 10(-6) mol/l) and thiorphan (1.0 x 10(-6) mol/l), while only captopril was found to potentiate the effects of the same peptides in the rat bladder. The four peptidase inhibitors, as well as bacitracin were found to modify the responses of the hamster urinary bladder to one or another or to all three groups of peptides and to DiMeC7. The present results suggest that the urinary bladders of various species have different types of active proteolytic enzymes: only the angiotensin-converting enzyme appears to be present in the rat bladder, while the same enzyme and possibly two additional endopeptidases interfere with the myotropic effects of neurokinins, kinins and angiotensins in the guinea pig and the hamster bladder.

Angiotensin II↗