title: A genome-wide study of two-component signal transduction systems in eight newly sequenced mutans streptococci strains.
abstract: BACKGROUND
  Mutans streptococci are a group of gram-positive bacteria including the primary cariogenic dental pathogen Streptococcus mutans and closely related species. Two component systems (TCSs) composed of a signal sensing histidine kinase (HK) and a response regulator (RR) play key roles in pathogenicity, but have not been comparatively studied for these oral bacterial pathogens.
  
  
  RESULTS
  HKs and RRs of 8 newly sequenced mutans streptococci strains, including S. sobrinus DSM20742, S. ratti DSM20564 and six S. mutans strains, were identified and compared to the TCSs of S. mutans UA159 and NN2025, two previously genome sequenced S. mutans strains. Ortholog analysis revealed 18 TCS clusters (HK-RR pairs), 2 orphan HKs and 2 orphan RRs, of which 8 TCS clusters were common to all 10 strains, 6 were absent in one or more strains, and the other 4 were exclusive to individual strains. Further classification of the predicted HKs and RRs revealed interesting aspects of their putative functions. While TCS complements were comparable within the six S. mutans strains, S. sobrinus DSM20742 lacked TCSs possibly involved in acid tolerance and fructan catabolism, and S. ratti DSM20564 possessed 3 unique TCSs but lacked the quorum-sensing related TCS (ComDE). Selected computational predictions were verified by PCR experiments.
  
  
  CONCLUSIONS
  Differences in the TCS repertoires of mutans streptococci strains, especially those of S. sobrinus and S. ratti in comparison to S. mutans, imply differences in their response mechanisms for survival in the dynamic oral environment. This genomic level study of TCSs should help in understanding the pathogenicity of these mutans streptococci strains.
authors.affiliation: Institute of Bioprocess and Biosystems Engineering, Hamburg University of Technology, Hamburg, Germany.
authors.forename: Lifu
authors.initials: L
authors.lastname: Song
authors.forename: Padhmanand
authors.initials: P
authors.lastname: Sudhakar
authors.forename: Wei
authors.initials: W
authors.lastname: Wang
authors.forename: Georg
authors.initials: G
authors.lastname: Conrads
authors.forename: Anke
authors.initials: A
authors.lastname: Brock
authors.forename: Jibin
authors.initials: J
authors.lastname: Sun
authors.forename: Irene
authors.initials: I
authors.lastname: Wagner-Döbler
authors.forename: An-Ping
authors.initials: AP
authors.lastname: Zeng
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D005798:Genes, Bacterial / Q000235:genetics; D023281:Genomics; D000071677:Histidine Kinase; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013045:Species Specificity; D013295:Streptococcus mutans / Q000166:cytology* / Q000201:enzymology / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D011494:Protein Kinases; D000071677:Histidine Kinase