Abstract
The expression of Escherichia coli type 1 fimbriae is phase-variable i.e. the bacterial cell is either fimbriated or non-fimbriated. The transition from one state to the other is caused by the change in configuration of an invertible DNA segment harbouring the promoter of the fimA gene. The position of this phase switch is controlled by two proteins, FimB and FimE, which mediate an 'on' or 'off' configuration of the switch, respectively. In this study, we have investigated how these proteins control the switch by means of fim-lac fusions on low-copy-number plasmids. It was found, by in trans and cis complementation, that the ratio of fimB to fimE and the total concentration of the gene products determine the configuration of the switch as well as the frequency of phase switching. It was also shown that transcription occurs from the promoter located at the phase switch when this is in the 'off' configuration. This suggests a regulatory mechanism, since the resulting transcript would be anti-sense to the fimE transcript.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
