Heme-responsive DNA binding by the global iron regulator Irr from Rhizobium leguminosarum

Singleton, Chloe, White, Gaye F., Todd, Jonathan D., Marritt, Sophie J., Cheesman, Myles R., Johnston, Andrew W. B. and Le Brun, N ORCID: https://orcid.org/0000-0001-9780-4061 (2010) Heme-responsive DNA binding by the global iron regulator Irr from Rhizobium leguminosarum. The Journal of Biological Chemistry, 285 (21). pp. 16023-16031. ISSN 1083-351X

Full text not available from this repository. (Request a copy)

Abstract

Heme, a physiologically crucial form of iron, is a cofactor for a very wide range of proteins and enzymes. These include DNA regulatory proteins in which heme is a sensor to which an analyte molecule binds, effecting a change in the DNA binding affinity of the regulator. Given that heme, and more generally iron, must be carefully regulated, it is surprising that there are no examples yet in bacteria in which heme itself is sensed directly by a reversibly binding DNA regulatory protein. Here we show that the Rhizobium leguminosarum global iron regulatory protein Irr, which has many homologues within the a-proteobacteria and is a member of the Fur superfamily, binds heme, resulting in a dramatic decrease in affinity between the protein and its cognate, regulatory DNA operator sequence. Spectroscopic studies of wild-type and mutant Irr showed that the principal (but not only) heme-binding site is at a conserved HXH motif, whose substitution led to loss of DNA binding in vitro and of regulatory function in vivo. The R. leguminosarum Irr behaves very differently to the Irr of Bradyrhizobium japonicum, which is rapidly degraded in vivo by an unknown mechanism in conditions of elevated iron or heme, but whose DNA binding affinity in vitro does not respond to heme.

Item Type:	Article
Faculty \ School:	Faculty of Science > School of Biological Sciences Faculty of Science > School of Chemistry
UEA Research Groups:	Faculty of Science > Research Groups > Molecular Microbiology Faculty of Science > Research Groups > Chemistry of Light and Energy Faculty of Science > Research Groups > Chemistry of Life Processes Faculty of Science > Research Groups > Biophysical Chemistry (former - to 2017) Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Depositing User:	Users 2731 not found.
Date Deposited:	26 Jan 2011 11:41
Last Modified:	11 Mar 2024 00:35
URI:	https://ueaeprints.uea.ac.uk/id/eprint/19013
DOI:	10.1074/jbc.M109.067215

Actions (login required)

View Item