title: Classical and El Tor biotypes of Vibrio cholerae differ in timing of transcription of tcpPH during growth in inducing conditions.
abstract: Two protein pairs in Vibrio cholerae, ToxRS and TcpPH, are necessary for transcription from the toxT promoter and subsequent expression of cholera virulence genes. We have previously shown that transcription of tcpPH in classical strains of V. cholerae is activated at mid-log-phase growth in ToxR-inducing conditions, while transcription of tcpPH in El Tor strains is not. In this study, we showed that while transcription of tcpPH differs at mid-log-phase growth in ToxR-inducing conditions between the biotypes, transcription is equivalently high during growth in AKI conditions. We used tcpPH::gusA transcriptional fusions to quantitate expression of tcpPH in each biotype throughout growth in ToxR-inducing conditions and showed that although transcription of tcpPH is reduced at mid-log-phase growth in an El Tor strain, transcription is turned on later in growth to levels in excess of those in the classical strain (although cholera toxin is not produced). This suggests that the difference in expression of cholera virulence factors in response to ToxR-inducing conditions between the El Tor and classical biotypes of V. cholerae may be related to the timing of transcription of tcpPH rather than the absolute levels of transcription.
authors.affiliation: Division of Infectious Diseases, Massachusetts General Hospital, Boston, Massachusetts 02114, USA.
authors.forename: Y M
authors.initials: YM
authors.lastname: Murley
authors.forename: J
authors.initials: J
authors.lastname: Behari
authors.forename: R
authors.initials: R
authors.lastname: Griffin
authors.forename: S B
authors.initials: SB
authors.lastname: Calderwood
mesh_terms: D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D001665:Binding Sites; D002874:Chromosome Mapping; D017931:DNA Primers; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins / Q000235:genetics; D036781:Fimbriae Proteins; D005966:Glucuronidase / Q000235:genetics; D008969:Molecular Sequence Data; D020871:RNA Stability; D012329:RNA, Bacterial; D012097:Repressor Proteins / Q000235:genetics; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics; D014158:Transcription, Genetic; D014734:Vibrio cholerae / Q000235:genetics* / Q000254:growth & development / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D017931:DNA Primers; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D012329:RNA, Bacterial; D012097:Repressor Proteins; C097244:TCPP protein, Vibrio cholerae; C099204:TcpH protein, Vibrio cholerae; C097245:TcpI protein, Vibrio cholerae; D014157:Transcription Factors; C499324:toxR protein, Vibrio cholerae; C066719:toxR protein, bacteria; D036781:Fimbriae Proteins; D005966:Glucuronidase