title: Intraspecific and interspecific interactions among proteins regulating exopolysaccharide synthesis in Streptococcus thermophilus, Streptococcus iniae, and Lactococcus lactis subsp. cremoris and the assessment of potential lateral gene transfer.
abstract: Using the yeast two-hybrid system, intraspecific protein interactions were detected in  Streptococcus iniae  and  Lactococcus lactis  subsp. cremoris between the transmembrane activation protein (CpsC and EpsA, respectively) and the protein tyrosine kinase (CpsD and EpsB, respectively), between two protein tyrosine kinases, and between the protein tyrosine kinase and the phosphotyrosine phosphatase (CpsB and EpsC, respectively). For each of these intraspecific interactions, interspecific interactions were also detected when one protein was from S. iniae and the other was from  Streptococcus thermophilus . Interactions were also observed between two protein tyrosine kinases when one protein was from either of the Streptococcus species and the other from L. lactis subsp. cremoris. The results and sequence comparisons performed in this study support the conclusion that interactions among the components of the tyrosine kinase - phosphatase regulatory system are conserved in the order Lactobacillales and that interspecific genetic exchanges of the genes that encode these proteins have the potential to form functional recombinants. A better understanding of intraspecific and interspecific protein interactions involved in regulating exopolysaccharide biosynthesis may facilitate construction of improved strains for industrial uses as well as identification of factors needed to form functional regulatory complexes in naturally occurring recombinants.
authors: Department of Biology, Utah State University, Logan, UT 84322, USA. ACefalo@biology.usu.edu
authors: Angela D
authors: AD
authors: Cefalo
authors: Jeffery R
authors: JR
authors: Broadbent
authors: Dennis L
authors: DL
authors: Welker
mesh_terms: D000595:Amino Acid Sequence; D016667:Bacterial Capsules / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D004798:Enzymes / Q000737:chemistry / Q000378:metabolism; D022761:Gene Transfer, Horizontal; D013294:Lactococcus lactis / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013291:Streptococcus / Q000235:genetics / Q000378:metabolism; D048249:Streptococcus thermophilus / Q000235:genetics / Q000378:metabolism; D020798:Two-Hybrid System Techniques
chemical_list: D001426:Bacterial Proteins; D004798:Enzymes