The serine-aspartate repeat (Sdr) protein family in Staphylococcus epidermidis

Kirk W. McCrea, Orla Hartford, Stacey Davis, Deirdre Ní Eidhin, Gerard Lina, Pietro Speziale, Timothy J. Foster, Magnus Höök

Research output: Contribution to journalArticle

122 Scopus citations

Abstract

Staphylococcus epidermidis can express three different cell-surface associated proteins, designated SdrF, SdrG and SdrH, that contain serine- aspartate dipeptide repeats. Proteins SdrF and SdrG are similar in sequence and structural organization to the Sdr proteins of Staphylococcus aureus and comprise unique 625- and 548-residue A regions at their N termini, respectively, followed by 110-119-residue B-repeat regions and SD-repeat regions. The C termini contain LPXTG motifs and hydrophobic amino acid segments characteristic of surface proteins covalently anchored to peptidoglycan. In contrast, SdrH has a short 60-residue A region at its N terminus followed by a SD-repeat region, a unique 277-residue C region and a C-terminal hydrophobic segment. SdrH lacks a LPXTG motif. Recombinant proteins representing the A regions of SdrF, SdrG and SdrH were expressed and purified from Escherichia coli. Antisera specific to these proteins were raised in rabbits and used to identify Sdr proteins expressed by S. epidermidis. Only SdrF was released from lysostaphin-generated protoplasts of cells grown to late-exponential phase. SdrG and SdrH remained associated with the protoplast fraction and thus appear to be ineffectively sorted along the conventional pathway used for cell-wall-anchored proteins. In Southern hybridization analyses, the sdrG and sdrH genes were present in all 16 strains tested, whilst sdrF was present in 12 strains. Antisera from 16 patients who had recovered from S. epidermidis infections contained antibodies that reacted with recombinant A regions of SdrG and SdrH, suggesting that these proteins can be expressed during infection.

Original languageEnglish (US)
Pages (from-to)1535-1546
Number of pages12
JournalMicrobiology
Volume146
Issue number7
DOIs
StatePublished - Jul 2000

Keywords

  • Adhesin
  • Multigene family
  • Surface protein

ASJC Scopus subject areas

  • Microbiology

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