Interaction of the Streptomyces Wbl protein WhiD with the principal sigma factor σHrdB depends on the WhiD [4Fe-4S] cluster

Stewart, Melissa, Bush, Matthew, Crack, Jason, Buttner, Mark and Le Brun, Nick (2020) Interaction of the Streptomyces Wbl protein WhiD with the principal sigma factor σHrdB depends on the WhiD [4Fe-4S] cluster. Journal of Biological Chemistry, 295 (28). pp. 9752-9765. ISSN 0021-9258

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Abstract

The bacterial protein WhiD belongs to the Wbl family of iron–sulfur [Fe-S] proteins present only in the actinomycetes. In Streptomyces coelicolor, it is required for the late stages of sporulation, but precisely how it functions is unknown. Here, we report results from in vitro and in vivo experiments with WhiD from Streptomyces venezuelae (SvWhiD), which differs from S. coelicolor WhiD (ScWhiD) only at the C terminus. We observed that, like ScWhiD and other Wbl proteins, SvWhiD binds a [4Fe-4S] cluster that is moderately sensitive to O2 and highly sensitive to nitric oxide (NO). However, although all previous studies have reported that Wbl proteins are monomers, we found that SvWhiD exists in a monomer–dimer equilibrium associated with its unusual C-terminal extension. Several Wbl proteins of Mycobacterium tuberculosis are known to interact with its principal sigma factor SigA. Using bacterial two-hybrid, gel filtration, and MS analyses, we demonstrate that SvWhiD interacts with domain 4 of the principal sigma factor of Streptomyces, σHrdB (σHrdB4). Using MS, we determined the dissociation constant (Kd) for the SvWhiD–σHrdB4 complex as ~0.7 μM, consistent with a relatively tight binding interaction. We found that complex formation was cluster dependent and that a reaction with NO, which was complete at 8–10 NO molecules per cluster, resulted in dissociation into the separate proteins. The SvWhiD [4Fe-4S] cluster was significantly less sensitive to reaction with O2 and NO when SvWhiD was bound to σHrdB4, consistent with protection of the cluster in the complex.

Item Type: Article
Uncontrolled Keywords: streptomyces,wbl proteins,whid,bacterial gene regulation,iron-sulfur cluster,iron-sulfur protein,mass spectrometry (ms),metalloprotein,microbiology,nitric oxide,protein dimerization,protein-protein interaction,sigma factor,sporulation,biochemistry,molecular biology,cell biology ,/dk/atira/pure/subjectarea/asjc/1300/1303
Faculty \ School: Faculty of Science > School of Chemistry
Faculty of Science > School of Biological Sciences
Related URLs:
Depositing User: LivePure Connector
Date Deposited: 05 May 2020 00:06
Last Modified: 18 Sep 2020 00:28
URI: https://ueaeprints.uea.ac.uk/id/eprint/74971
DOI: 10.1074/jbc.RA120.012708

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