Topic
C5a peptidase
About: C5a peptidase is a research topic. Over the lifetime, 49 publications have been published within this topic receiving 2392 citations.
Papers
TL;DR: It is demonstrated that affinity-purified recombinant ScpB and a peptide Scp B fragment (ScpB-PDF), similar to the peptide identified in the phagemid, bound fibronectin in a concentration-dependent manner, suggesting a second important role for this surface protein in the pathogenesis of GBS infections.
Abstract: 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.
191 citations
TL;DR: Using a murine model of human NF, it is demonstrated that ScpC, but not the C5a peptidase ScpA, is an essential virulence factor and SilCR pheromone downregulates scpC transcription via the two‐component system—SilA/B.
Abstract: Group A Streptococcus (GAS) causes the life-threatening infection in humans known as necrotizing fasciitis (NF). Infected subcutaneous tissues from an NF patient and mice challenged with the same GAS strain possessed high bacterial loads but a striking paucity of infiltrating polymorphonuclear leukocytes (PMNs). Impaired PMN recruitment was attributed to degradation of the chemokine IL-8 by a GAS serine peptidase. Here, we use bioinformatics approach coupled with target mutagenesis to identify this peptidase as ScpC. We show that SilCR pheromone downregulates scpC transcription via the two-component system—SilA/B. In addition, we demonstrate that in vitro, ScpC degrades the CXC chemokines: IL-8 (human), KC, and MIP-2 (both murine). Furthermore, using a murine model of human NF, we demonstrate that ScpC, but not the C5a peptidase ScpA, is an essential virulence factor. An ScpC-deficient mutant is innocuous for untreated mice but lethal for PMN-depleted mice. ScpC degrades KC and MIP-2 locally in the infected skin tissues, inhibiting PMN recruitment. In conclusion, ScpC represents a novel GAS virulence factor functioning to directly inactivate a key element of the host innate immune response.
186 citations
TL;DR: Rabbit anti-SCPB serum inhibited invasion of lung epithelial A549 cells by the serotype Ia strain O90R, suggesting that SCPB is an invasin.
Abstract: The group B streptococcus (GBS) is a major cause of pneumonia, sepsis, and meningitis in neonates and a serious cause of mortality or morbidity in immunocompromised adults. Although these streptococci adhere efficiently and invade a variety of tissue-specific epithelial and endothelial cells, adhesins and invasins are still unknown. All serotypes of GBS studied to date express C5a peptidase (SCPB) on their surface. This investigation addresses the possibility that this relatively large surface protein has additional activities. Rabbit anti-SCPB serum inhibited invasion of lung epithelial A549 cells by the serotype Ia strain O90R, suggesting that SCPB is an invasin. This was confirmed by inserting an in-frame 25-amino-acid deletion into the scpB gene. Invasion of HEp2 and A549 human cell lines was significantly reduced by the mutation. Enzyme-linked immunosorbent assays were used to demonstrate that purified SCPB protein binds directly to HEp2 and A549 cells and also binds the extracellular matrix protein fibronectin. Binding was dose dependent and saturable. These results suggested that SCPB is one of several potential invasins essential for GBS colonization of damaged epithelium.
169 citations
TL;DR: The near identity of GBS and GAS peptidases is consistent with horizontal transmission of the scp gene between these species.
Abstract: The chromosome of group B streptococci (GBS) contains a gene which is related to the C5a peptidase gene (scpA) of group A streptococci (GAS). scpA encodes a surface-associated peptidase (group A streptococcal C5a peptidase [SCPA]) which specifically cleaves C5a, a major chemoattractant generated in serum by activation of complement. The entire scpA-like gene (scpB) was cloned from a GBS strain and sequenced. The gene encodes an open reading frame of 3,450 bp, which corresponds to a deduced protein (SCPB) of 1,150 amino acids with a molecular weight of 126,237 Da. Nucleotide and deduced amino acid sequences of SCPB were found to be highly homologous to those of SCPAs from GAS. Unexpectedly, scpA12 is more similar to scpB than to another GAS gene, scpA49. The sequence 5' of the open reading frame, including transcription start and a termination site in the signal sequence, is also similar to that of scpA, although less conserved than the coding sequences. The near identity of GBS and GAS peptidases is consistent with horizontal transmission of the scp gene between these species. Recombinant SCPB was expressed in Escherichia coli by using the expression vector plasmid pGEX-4T-1 and was shown to be identical in size to the enzyme extracted from the parental GBS strain 78-471.
146 citations
TL;DR: Results demonstrate that LPXTG-containing proteins are involved in cell adhesion and GBS persistence in vivo.
Abstract: Streptococcus agalactiae (group B streptococcus [GBS]) is the leading cause of neonatal pneumonia, sepsis, and meningitis. An in silico genome analysis indicated that GBS strain NEM316 encodes 35 proteins containing an LPXTG motif which are thought to be covalently linked to the peptidoglycan by an enzyme called sortase. The role of these cell wall-anchored proteins in GBS pathogenesis was evaluated on a global level by inactivating the srtA gene. This gene encodes the major sortase SrtA that anchors most of the LPXTG-containing proteins. We chose the C5a peptidase (ScpB) and Alp2, an abundant immunogenic protein, as prototypical LPXTG-containing proteins. As expected, the SrtA knockout mutant was unable to anchor the C5a peptidase (ScpB) and Alp2 to the cell wall. Complementation with plasmid-borne srtA inserted into the chromosome restored the correct surface localization of both ScpB and Alp2. Interestingly, the SrtA mutant was impaired for binding to the major extracellular matrix components fibronectin and fibrinogen and displayed a significant reduction in adherence to human (A549, HeLa, and Caco-2) and murine (L2) epithelial cells compared to the parental wild-type strain. Surprisingly, the inactivation of srtA had no effect on the virulence of the type III strain of GBS in a neonatal rat model (measured by the 50% lethal dose and lung colonization) but strongly impaired the capacity of the strain to colonize the intestines of gnotobiotic mice in a competition assay. These results demonstrate that LPXTG-containing proteins are involved in cell adhesion and GBS persistence in vivo.
125 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2021 | 2 |
| 2020 | 1 |
| 2019 | 1 |
| 2017 | 1 |
| 2015 | 1 |
| 2013 | 3 |