title: Identification of salivary mucin MUC7 binding proteins from Streptococcus gordonii.
abstract: BACKGROUND
  The salivary mucin MUC7 (previously known as MG2) can adhere to various strains of streptococci that are primary colonizers and predominant microorganisms of the oral cavity. Although there is a growing interest in interaction between oral pathogens and salivary mucins, studies reporting the specific binding sites on the bacteria are rather limited. Identification and characterization of the specific interacting proteins on the bacterial cell surface, termed adhesins, are crucial to further understand host-pathogen interactions.
  
  
  RESULTS
  We demonstrate here, using purified MUC7 to overlay blots of SDS-extracts of Streptococcus gordonii cell surface proteins, 4 MUC7-binding bands, with apparent molecular masses of 62, 78, 84 and 133 kDa from the Streptococcus gordonii strain, PK488. Putative adhesins were identified by in-gel digestion and subsequent nanoLC-tandem mass spectrometry analysis of resultant peptides. The 62 kDa and 84 kDa bands were identified as elongation factor (EF) Tu and EF-G respectively. The 78 kDa band was a hppA gene product; the 74 kDa oligopeptide-binding lipoprotein. The 133 kDa band contained two proteins; alpha enolase and DNA-directed RNA polymerase, beta' subunit. Some of these proteins, for example alpha enolase are expected to be intracellular, however, flow cytometric analysis confirmed its location on the bacterial surface.
  
  
  CONCLUSIONS
  Our data demonstrated that S. gordonii expressed a number of putative MUC7 recognizing proteins and these contribute to MUC7 mucin binding of this streptococcal strain.
authors: Department of Biochemistry, Faculty of Medicine, University of Gazi, 06510 Besevler, Ankara, Turkey. kesimer@med.unc.edu
authors: Mehmet
authors: M
authors: Kesimer
authors: Nedret
authors: N
authors: Kiliç
authors: Ravi
authors: R
authors: Mehrotra
authors: David J
authors: DJ
authors: Thornton
authors: John K
authors: JK
authors: Sheehan
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics / Q000302:isolation & purification*; D005434:Flow Cytometry; D006801:Humans; D009077:Mucins / Q000378:metabolism*; D011485:Protein Binding; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D054773:Streptococcus gordonii / Q000235:genetics*; D053719:Tandem Mass Spectrometry
chemical_list: D018829:Adhesins, Bacterial; C083238:MUC7 protein, human; D009077:Mucins; D012471:Salivary Proteins and Peptides