title: Sec translocase and sortase A are colocalised in a locus in the cytoplasmic membrane of Streptococcus mutans.
abstract: BACKGROUND
  The general secretory (Sec) pathway is the main pathway for protein transport. Sortase A has been shown to anchor surface protein containing an LPXTG motif to the cell wall. In order to know the distribution pattern of the Sec translocons and sortase A in Streptococcus mutans, we explored the subcellular localisation of SecA and sortase A.
  
  
  METHODS
  The anti-SecA antibody and anti-sortase A antibody were examined on Western blots to evaluate specificities. An indirect post-embedding immunogold method was used to determine the subcellular localisation of the Sec pathway and sortase A enzyme in S. mutans membrane.
  
  
  RESULTS
  Immunoblotting experiments showed that the anti-SecA antibody and anti-sortase A antibody specifically recognised a single band of about 95 kDa and 27 kDa, respectively in the S. mutans GS-5 cell lysates. Immunogold electron micrographs showed that small and large gold particles clustered together at a distinct microdomain.
  
  
  CONCLUSIONS
  These data showed for the first time that Sec translocase and sortase A colocalised to a single locus in the cytoplasmic membrane of S. mutans GS-5.
authors.affiliation: The Key Laboratory for Oral Biomedical Engineering of Ministry of Education, School and Hospital of Stomatology, Wuhan University, 237 Luoyu Road, Wuhan 430079, China. gloriaping@126.com
authors.forename: Ping
authors.initials: P
authors.lastname: Hu
authors.forename: Zhuan
authors.initials: Z
authors.lastname: Bian
authors.forename: Mingwen
authors.initials: M
authors.lastname: Fan
authors.forename: Meijing
authors.initials: M
authors.lastname: Huang
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
mesh_terms: D019881:Aminoacyltransferases / Q000378:metabolism*; D000942:Antigens, Bacterial / Q000737:chemistry* / Q000378:metabolism; D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics; D002473:Cell Wall / Q000737:chemistry* / Q000378:metabolism; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006801:Humans; D008855:Microscopy, Electron, Scanning; D009154:Mutation; D021381:Protein Transport / Q000235:genetics; D013295:Streptococcus mutans / Q000201:enzymology* / Q000235:genetics
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D002352:Carrier Proteins; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases