Inactivation of the srtA gene affects localization of surface proteins and decreases adhesion of Streptococcus pneumoniae to human pharyngeal cells in vitro.
Inactivation of sortase gene srtA in Streptococcus pneumoniae strain R6 caused the release of beta-galactosidase and neuraminidase A (NanA) from the cell wall into the surrounding medium. Both of these surface proteins contain the LPXTG motif in the C-terminal domain. Complementation with plasmid-borne srtA reversed protein release. Deletion of murM, a gene involved in the branching of pneumococcal peptidoglycan, also caused partial release of beta-galactosidase, suggesting preferential attachment of the protein to branched muropeptides in the cell wall. Inactivation of srtA caused decreased adherence to human pharyngeal cells in vitro but had no effect on the virulence of a capsular type III strain of S. pneumoniae in the mouse intraperitoneal model. The observations suggest that--as in other gram-positive bacteria--sortase-dependent display of proteins occurs in S. pneumoniae and that some of these proteins may be involved in colonization of the human host.
Kharat
Arun S
AS
Laboratory of Microbiology, The Rockefeller University, New York, New York 10021, USA.
Tomasz
Alexander
A
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics* / Q000502:physiology; D000818:Animals; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000032:analysis*; D002460:Cell Line; D003546:Cysteine Endopeptidases; D006801:Humans; D008565:Membrane Proteins / Q000032:analysis; D051379:Mice; D008969:Molecular Sequence Data; D009439:Neuraminidase / Q000032:analysis*; D010614:Pharynx / Q000382:microbiology*; D013296:Streptococcus pneumoniae / Q000235:genetics* / Q000502:physiology; D014774:Virulence; D001616:beta-Galactosidase / Q000032:analysis*
D001426:Bacterial Proteins; D008565:Membrane Proteins; D019881:Aminoacyltransferases; C120542:sortase A; D009439:Neuraminidase; D001616:beta-Galactosidase; D003546:Cysteine Endopeptidases