title: Protein-protein interactions among the components of the biosynthetic machinery responsible for exopolysaccharide production in Streptococcus thermophilus MR-1C.
abstract: OBJECTIVE
  This study identified protein-protein interactions among the biosynthetic machinery responsible for exopolysaccharide (EPS) production in Streptococcus thermophilus MR-1C.
  
  
  RESULTS
  Protein-protein interactions were investigated using the yeast two-hybrid system. A strong protein-protein interaction was detected between the transmembrane activation protein Wzd and the protein tyrosine kinase Wze. Weaker protein-protein interactions were detected between two duplicate Wze proteins and between Wze and the phosphotyrosine phosphatase Wzh. Protein-protein interactions involving a Wzd/Wze fusion protein and Wzd and Wze may indicate that these proteins form multi-protein complexes. All combinations of the Wzh, Wzd, Wze, Wzg (regulation), CpsE (glycosyl-1-phosphate transferase), CpsS (polymerization), CpsL (unknown), CpsW (regulation) and CpsU (membrane translocation) were analysed for protein-protein interactions but no additional interactions were discovered using the yeast two-hybrid system.
  
  
  CONCLUSIONS
  Interactions among the phosphotyrosine phosphatase, tyrosine kinase, and transmembrane activation protein are important in the regulation of capsule biosynthesis in Strep. thermophilus MR-1C.
  
  
  CONCLUSIONS
  This study provides some valuable insight into the organization and interactions between the many proteins involved in EPS production. A better understanding of this process may facilitate the genetic manipulation of capsule production to impart desirable properties to dairy starter cultures.
authors.affiliation: Department of Biology, Utah State University, 5305 Old Main Hill, Logan, UT 84322-5305, USA. acefalo@biology.usu.edu
authors.forename: A D
authors.initials: AD
authors.lastname: Cefalo
authors.forename: J R
authors.initials: JR
authors.lastname: Broadbent
authors.forename: D L
authors.initials: DL
authors.lastname: Welker
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism*; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D017027:Protein Tyrosine Phosphatases / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D048249:Streptococcus thermophilus / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D011135:Polysaccharides, Bacterial; D011994:Recombinant Proteins; D017027:Protein Tyrosine Phosphatases