Award details

RirA - a new paradigm for iron-mediated gene regulation in bacteria?

Reference	BB/C502822/1
Principal Investigator / Supervisor	Professor Andrew Johnston
Co-Investigators / Co-Supervisors
Institution	University of East Anglia
Department	Biological Sciences
Funding type	Research
Value (£)	76,030
Status	Completed
Type	Research Grant
Start date	01/03/2005
End date	28/02/2007
Duration	24 months

Abstract

This application aims to extend our knowledge of RirA, a novel regulator of genes whose transcription is affected by the availability of Fe. This system, initially identified in the N2-fixing symbiont Rhizobium leguminosarum, may have close parallels in near relatives of these bacteria. The work will involve the following: (a) Identification of a range of promoters and their attendant cis-acting regulatory sequences in a selection of genes whose expression is repressed by Fe, if rirA is present. The target genes will include those that contain a sequence, which we term an IRO motif which is important for RirA-mediated repression and those that do not and which show subtle, but significantly different responses to rirA in different genetic backgrounds. (b) We recently found that some genes may be positively regulated by RirA. As in (a) above, promoters and operators of some of these will be analysed to assess the cis-acting sequences involved in this form of regulation. (c) There is circumstantial evidence that RirA may bind to a cofactor, possibly a FeS cluster. This will be examined biochemically by purifying RirA in the presence of FeS and examining the protein spectroscopically. The effects of mutating genes involved in FeS synthesis on RirA¿s properties will also be examined, as a genetic way of addressing this point. (d) In Rhizobium and in Brucella, rirA mutants are hyper-sensitive to peroxide. We will examine the RirA regulon in response to oxidative stress and compare that with the situation when Fe concentrations are modulated. (e) Using microarray analyses, we will attempt to make an inventory of all the Rhizobium genes whose expression is affected by Fe availability and by the rirA genotype. (f) Because some Rhizobium Fe-responsive genes are also regulated in Paracoccus, but some are not, we will identify the regulatory genes in this related, alpha-proteobacterium.

Summary

unavailable

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

I accept the terms and conditions of use (opens in new window)

export PDF file

back to list new search