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Differentiated, promoter-specific response of [4Fe-4S] NsrR DNA binding to reaction with nitric oxide

Crack, JC and Svistunenko, DA and Munnoch, J and Thomson, AJ and Hutchings, MI and Le Brun, NE (2016) 'Differentiated, promoter-specific response of [4Fe-4S] NsrR DNA binding to reaction with nitric oxide.' Journal of Biological Chemistry, 291 (16). 8663 - 8672. ISSN 0021-9258

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Abstract

© 2016 by The American Society for Biochemistry and Molecular Biology, Inc. NsrR is an iron-sulfur cluster protein that regulates the nitric oxide (NO) stress response of many bacteria. NsrR from Streptomyces coelicolor regulates its own expression and that of only two other genes, hmpA1 and hmpA2, which encode HmpA enzymes predicted to detoxify NO. NsrR binds promoter DNA with high affinity only when coordinating a [4Fe-4S] cluster. Here we show that reaction of [4Fe-4S] NsrR with NO affects DNA binding differently depending on the gene promoter. Binding to the hmpA2 promoter was abolished at ∼2 NO per cluster, although for the hmpA1 and nsrR promoters, ∼4 and ∼8 NO molecules, respectively, were required to abolish DNA binding. Spectroscopic and kinetic studies of the NO reaction revealed a rapid, multi-phase, non-concerted process involving up to 8-10 NO molecules per cluster, leading to the formation of several iron-nitrosyl species. A distinct intermediate was observed at ∼2 NO per cluster, along with two further intermediates at ∼4 and ∼6 NO. The NsrR nitrosylation reaction was not significantly affected by DNA binding. These results show that NsrR regulates different promoters in response to different concentrations of NO. Spectroscopic evidence indicates that this is achieved by different NO-FeS complexes.

Item Type: Article
Subjects: Q Science > QH Natural history > QH301 Biology
Divisions: Faculty of Science and Health > Biological Sciences, School of
Depositing User: Jim Jamieson
Date Deposited: 27 May 2016 13:17
Last Modified: 30 Jan 2019 16:20
URI: http://repository.essex.ac.uk/id/eprint/16818

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