Mutagenesis of RpoE-like sigma factor genes in Bdellovibrio reveals differential control of groEL and two groES genes.
BACKGROUND
Bdellovibrio bacteriovorus HD100 must regulate genes in response to a variety of environmental conditions as it enters, preys upon and leaves other bacteria, or grows axenically without prey. In addition to "housekeeping" sigma factors, its genome encodes several alternate sigma factors, including 2 Group IV-RpoE-like proteins, which may be involved in the complex regulation of its predatory lifestyle.


RESULTS
We find that one sigma factor gene, bd3314, cannot be deleted from Bdellovibrio in either predatory or prey-independent growth states, and is therefore possibly essential, likely being an alternate sigma 70. Deletion of one of two Group IV-like sigma factor genes, bd0881, affects flagellar gene regulation and results in less efficient predation, although not due to motility changes; deletion of the second, bd0743, showed that it normally represses chaperone gene expression and intriguingly we find an alternative groES gene is expressed at timepoints in the predatory cycle where intensive protein synthesis at Bdellovibrio septation, prior to prey lysis, will be occurring.


CONCLUSIONS
We have taken the first step in understanding how alternate sigma factors regulate different processes in the predatory lifecycle of Bdellovibrio and discovered that alternate chaperones regulated by one of them are expressed at different stages of the lifecycle.
Centre for Genetics and Genomics, School of Biology, University of Nottingham Medical School, QMC, Nottingham, NG7 2UH, UK.
Carey
C
Lambert
Rob
R
Till
Laura
L
Hobley
R Elizabeth
RE
Sockett
D001501:Bdellovibrio / Q000235:genetics*; D018835:Chaperonin 10 / Q000096:biosynthesis* / Q000235:genetics; D018834:Chaperonin 60 / Q000096:biosynthesis* / Q000235:genetics; D005407:Flagella / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D020043:Genes, Essential; D016296:Mutagenesis; D012808:Sigma Factor / Q000235:genetics*
D018835:Chaperonin 10; D018834:Chaperonin 60; D012808:Sigma Factor