Function and Environmental Regulation ofkpsF, the First Gene of the Region One Operon of Escherichia Coli K1

Temperature is the only environmental stimulus currently known to affect K1 capsule expression. Capsule is maximally expressed at body temperature (37$\sp\circ$C or 98.6$\sp\circ$F), but is turned off at temperatures commonly encountered in the external environment, below about 26$\sp\circ$C. Expression of the first gene of the region 1 operon, kpsF, is controlled by thermal regulation of a σ70-type promoter. Thus, thermoregulation of the region 1 operon appears to involve a new mechanism controlling the in vivo expression of an important virulence factor. A promoterless non-polar kanamycin cassette inserted into kpsF has no detectable phenotype when mutant cells were cross-streaked against the K1 capsule specific bacteriophage, K1F. However, more sensitive assays for the capsule exhibited an intermediate capsule phenotype, including reduced plaque size and decreased surface expression of polysialic acid. These results indicate that KpsF is not obligatory for capsule synthesis or transport, although KpsF may be necessary for normal transport and assembly of a wild type capsule. A potential nucleotide binding site and helix-turn-helix motif predicted from the kpsF sequence are primary structural features of KpsF that are consistent with its hypothesized regulatory function. Two other KpsF homologs, GutQ and Orf328, have been identified in Escherichia coli, while additional homologs have been found in other genera suggesting that KpsF is a member of a new family of regulatory proteins that may be of general importance in diverse host-microbe interactions.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Veterinary Pathobiology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

1997

Author dc:creator

• Cieslewicz, Michael John

Contributors dc:contributor

• Vimr, Eric R.

• Biology, Molecular

Language dc:language

eng

Identifier

(MiAaPQ)AAI9737077

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/87641