Maturation of Streptococcus pneumoniae lipoproteins by a type II signal peptidase is required for ABC transporter function and full virulence.
Cell surface lipoproteins are important for the full virulence of several bacterial pathogens, including Streptococcus pneumoniae. Processing of prolipoproteins seems to be conserved among different bacterial species, and requires type II signal peptidase (Lsp) mediated cleavage of the N-terminal signal peptide to form the mature lipoprotein. Lsp has been suggested as a target for new antibiotic therapies, but at present there are only limited data on the function of Lsp for Gram-positive bacterial pathogens. We have investigated the function and role during disease pathogenesis of the S. pneumoniae Lsp, which, blast searches suggest, is encoded by the gene Sp0928. Expression of Sp0928 protected Escherichia coli against the Lsp antagonist globomycin, and proteomics and immunoblot analysis demonstrated that deletion of Sp0928 prevented processing of S. pneumoniae prolipoproteins to mature lipoproteins. These data strongly suggest that Sp0928 encodes the S. pneumoniae Lsp. However, immunoblots of membrane-associated proteins, immunoelectron microscopy and flow cytometry assays all confirmed that in the absence of Lsp, immature lipoproteins were still attached to the cell surface. Despite preservation of lipoprotein attachment to the cell membrane, loss of S. pneumoniae Lsp resulted in several phenotypes associated with impaired lipoprotein function and reduced S. pneumoniae replication in animal models of infection.
Khandavilli
Suneeta
S
Centre for Respiratory Research, Department of Medicine, Royal Free and University College Medical School, Rayne Institute, London WC1E 6JJ, UK.
Homer
Karen A
KA
Yuste
Jose
J
Basavanna
Shilpa
S
Mitchell
Timothy
T
Brown
Jeremy S
JS
D018528:ATP-Binding Cassette Transporters / Q000378:metabolism*; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D015169:Colony Count, Microbial; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D015151:Immunoblotting; D008074:Lipoproteins / Q000378:metabolism*; D008168:Lung / Q000382:microbiology; D051379:Mice; D010455:Peptides / Q000494:pharmacology; D011008:Pneumococcal Infections / Q000382:microbiology; D011499:Protein Processing, Post-Translational / Q000502:physiology*; D020543:Proteome / Q000032:analysis; D013154:Spleen / Q000382:microbiology; D013296:Streptococcus pneumoniae / Q000378:metabolism* / Q000472:pathogenicity*; D016019:Survival Analysis; D014774:Virulence
D018528:ATP-Binding Cassette Transporters; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D008074:Lipoproteins; D010455:Peptides; D020543:Proteome; C017339:globomycin; D016282:Aspartic Acid Endopeptidases; C095652:signal peptidase II