Orientational control of fimE expression in Escherichia coli

Citation
Bk. Sohanpal et al., Orientational control of fimE expression in Escherichia coli, MOL MICROB, 42(2), 2001, pp. 483-494
Citations number
49
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
MOLECULAR MICROBIOLOGY
ISSN journal
0950-382X → ACNP
Volume
42
Issue
2
Year of publication
2001
Pages
483 - 494
Database
ISI
SICI code
0950-382X(200110)42:2<483:OCOFEI>2.0.ZU;2-N
Abstract
Phase-variable expression of type I fimbriae is, in part, controlled by sit e-specific DNA inversion of the fim switch in Escherichia coli. Of the two firn recombinases (FimB and FimE) that catalyse the inversion reaction, Fim E exhibits a strong bias for phase switching from the ON to the OFF orienta tion. The specificity associated with fimE is the result of two different m echanisms: (i) FimE exhibits a preference for the invertible element in the ON orientation as substrate for recombination; (ii) the invertible element in the OFF orientation acts in cis to inhibit recombinase activity (orient ational control). We show here that the invertible element negatively regul ates fimE, even though expression of a fimE-lacZYA transcriptional fusion i s unaffected by orientational control. The fimE transcript extends into the invertible region and hence switch ON-specific and switch OFF-specific mRN A contain different sequences. Furthermore, we show that orientational cont rol is suppressed by the insertion of a structured RNA (tRNA(Gly)) between fimE and the fim switch, indicating that the switch OFF-specific mRNA is in activated by 3' to 5' degradation. Analysis of the fim switch reveals that it contains two inhibitory elements that exert orientational control indepe ndently.