Probing the mechanism of the dedicated NO sensor [4Fe-4S] NsrR: the effect of cluster ligand environment

Dodd, Erin L. and Le Brun, Nick E. ORCID: (2024) Probing the mechanism of the dedicated NO sensor [4Fe-4S] NsrR: the effect of cluster ligand environment. Journal of Inorganic Biochemistry, 252. ISSN 0162-0134

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NsrR from Streptomyces coelicolor is a bacterial nitric oxide (NO) sensor/nitrosative stress regulator as its primary function, and has been shown to have differential response at low, mid, and high levels of NO. These must correspond to discrete structural changes at the protein-bound [4Fe-4S] cluster in response to stepwise nitrosylation of the cluster. We have investigated the effect of the monohapto carboxylate ligand in the site differentiated [4Fe-4S] cluster cofactor of the protein NsrR on modulating its reactivity to NO with a focus on indentifying mechanistic intermediates. We have prepared a synthetic model [4Fe-4S] cluster complex with tripodal ligand and one single site differentiated site occupied by either thiolate or carboxylate ligand. We report here the mechanistic details of sequential steps of nitrosylation as observed by ESI MS and IR spectroscopy. Parallel non-denaturing mass spectrometry analyses were performed using site-differentiated variants of NsrR with the native aspartic acid, cysteine, or alanine in the position of the forth ligand to the cluster. A mono-nitrosylated synthetic [4Fe-4S] cluster was observed for the first time in a biologically-relevant thiolate-based coordination environment. Combined synthetic and protein data give unprecedented clarity in the modulation of nitrosylation of a [4Fe-4S] cluster.

Item Type: Article
Additional Information: Acknowledgments: This work was supported by the Royal Society through the Newton International Postdoctoral Fellowship Fund, awarded to ELD under host NLB, as well as the Biotechnology and Biological Sciences Research Council Grants (BB/J003247/1 and BB/P006140/1). The authors would like to thank Prof. Chris Pickett of the University of East Anglia for synthetic lab space and instrumentation. We also acknowledge the influence of unpublished results by Eric Victor and Stephen J. Lippard of the Massachusetts Institute of Technology.
Uncontrolled Keywords: biomimetic model complex,mass spectrometry coordination chemistry,no sensor protein,[4fe-4s] cluster nitrosylation,biochemistry,inorganic chemistry ,/dk/atira/pure/subjectarea/asjc/1300/1303
Faculty \ School: Faculty of Science > School of Chemistry
UEA Research Groups: Faculty of Science > Research Centres > Centre for Molecular and Structural Biochemistry
Faculty of Science > Research Groups > Chemistry of Life Processes
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Depositing User: LivePure Connector
Date Deposited: 03 Jan 2024 03:19
Last Modified: 27 Jan 2024 03:14
DOI: 10.1016/j.jinorgbio.2023.112457

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