Proteomic and transcriptomic profiling of Staphylococcus aureus surface LPXTG-proteins: correlation with agr genotypes and adherence phenotypes

Mol Cell Proteomics. 2012 Nov;11(11):1123-39. doi: 10.1074/mcp.M111.014191. Epub 2012 Jul 25.


Staphylococcus aureus infections involve numerous adhesins and toxins, which expression depends on complex regulatory networks. Adhesins include a family of surface proteins covalently attached to the peptidoglycan via a conserved LPXTG motif. Here we determined the protein and mRNA expression of LPXTG-proteins of S. aureus Newman in time-course experiments, and their relation to fibrinogen adherence in vitro. Experiments were performed with mutants in the global accessory-gene regulator (agr), surface protein A (Spa), and fibrinogen-binding protein A (ClfA), as well as during growth in iron-rich or iron-poor media. Surface proteins were recovered by trypsin-shaving of live bacteria. Released peptides were analyzed by liquid chromatography coupled to tandem mass-spectrometry. To unambiguously identify peptides unique to LPXTG-proteins, the analytical conditions were refined using a reference library of S. aureus LPXTG-proteins heterogeneously expressed in surrogate Lactococcus lactis. Transcriptomes were determined by microarrays. Sixteen of the 18 LPXTG-proteins present in S. aureus Newman were detected by proteomics. Nine LPXTG-proteins showed a bell-shape agr-like expression that was abrogated in agr-negative mutants including Spa, fibronectin-binding protein A (FnBPA), ClfA, iron-binding IsdA, and IsdB, immunomodulator SasH, functionally uncharacterized SasD, biofilm-related SasG and methicillin resistance-related FmtB. However, only Spa and SasH modified their proteomic and mRNA profiles in parallel in the parent and its agr- mutant, whereas all other LPXTG-proteins modified their proteomic profiles independently of their mRNA. Moreover, ClfA became highly transcribed and active in fibrinogen-adherence tests during late growth (24 h), whereas it remained poorly detected by proteomics. On the other hand, iron-regulated IsdA-B-C increased their protein expression by >10-times in iron-poor conditions. Thus, proteomic, transcriptomic, and adherence-phenotype demonstrated differential profiles in S. aureus. Moreover, trypsin peptide signatures suggested differential protein domain exposures in various environments, which might be relevant for anti-adhesin vaccines. A comprehensive understanding of the S. aureus physiology should integrate all three approaches.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacterial Adhesion / drug effects
  • Bacterial Adhesion / genetics*
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Databases, Protein
  • Gene Expression Profiling*
  • Gene Expression Regulation, Bacterial / drug effects
  • Genotype
  • Iron / pharmacology
  • Kinetics
  • Lactococcus / drug effects
  • Lactococcus / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Microbial Viability / drug effects
  • Mutation / genetics*
  • Peptide Library
  • Peptides / metabolism
  • Phenotype
  • Proteomics*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Staphylococcus aureus / drug effects
  • Staphylococcus aureus / genetics*
  • Staphylococcus aureus / growth & development
  • Staphylococcus aureus / metabolism*
  • Trypsin / metabolism


  • Bacterial Proteins
  • Membrane Proteins
  • Peptide Library
  • Peptides
  • RNA, Messenger
  • Iron
  • Trypsin