Expression of the type 1 pneumococcal pilus is bistable and negatively regulated by the structural component RrgA.

ABSTRACT: The pneumococcal type 1 pilus, which is present in 25 to 30% of clinical isolates, has been associated with increased adherence and inflammatory responses and is being evaluated as a potential vaccine candidate. Here we show that expression of the pilus is bistable as a result of the molecular interaction between the transcription activator RrlA and a structural component of the pilus called RrgA. Sampling various clinical pneumococcal isolates that harbor the type 1 pilus-encoding islet, we show that distinct populations of cells can be identified with either undetectable or prominent pilus expression. When these two populations are separated and regrown in liquid medium, they are phenotypically different: the nonexpressing population reverts to the previous bimodal distribution, whereas

SUBMITTER: Basset A 

PROVIDER: S-EPMC3147576 | biostudies-literature | 2011 Aug

REPOSITORIES: biostudies-literature