Editors' ChoiceBacterial Gene Expression

Cross Talk Between Fimbrial Gene Clusters

STKE  11 Apr 2000:
Vol. 2000, Issue 27, pp. tw2
DOI: 10.1126/stke.2000.27.tw2

The expression of adhesive pili, also known as fimbriae, is an important characteristic of pathogenic bacteria. Uropathogenic Escherichia coli contain multiple fimbrial gene clusters yet normally express only one fimbrial type at any given time. Xia et al. demonstrate that PapB, a regulator of the expression of P fimbriae, encoded by the pap gene cluster, also regulates expression of type 1 fimbriae, encoded by the fim gene cluster. The type 1 fimbriae operon is regulated by switching the orientation of the promoter for the main fim gene from the on-to-off orientation by the FimE and FimB recombinases and from the off-to-on orientation by the FimB recombinase. PapB increases the on-to-off transition by increasing FimE expression and inhibits the off-to-on transition by directly blocking the activity of the FimB recombinase at the fim switch. This cross talk between the pap and fim gene clusters provides a mechanism for expression of only a single fimbrial type.

Xia, Y., Gally, D., Forsman-Semb, K., and Uhlin, B.E. (2000) Regulatory cross-talk between adhesin operons in Escherichia coli: inhibition of type 1 fimbriae expression by the PapB protein. EMBO J. 19: 1450-1457. [Abstract] [Full Text]