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Correct assembly of iron-sulfur cluster FS0 into Escherichia coli dimethyl sulfoxide reductase (DmsABC) is a prerequisite for molybdenum cofactor insertion.

ABSTRACT: The FS0 [4Fe-4S] cluster of the catalytic subunit (DmsA) of Escherichia coli dimethyl sulfoxide reductase (DmsABC) plays a key role in the electron transfer relay. We have now established an additional role for the cluster in directing molybdenum cofactor assembly during enzyme maturation. EPR spectroscopy indicates that FS0 has a high spin ground state (S = 3/2) in its reduced form, resulting in an EPR spectrum with a peak at g ? 5.0. The cluster is predicted to be in close proximity to the molybdo-bis(pyranopterin guanine dinucleotide) (Mo-bisPGD) cofactor, which provides the site of dimethyl sulfoxide reduction. Comparison with nitrate reductase A (NarGHI) indicates that a sequence of residues ((18)CTVNC(22)) plays a role in both FS0 and Mo-bisPGD coordination. A DmsA(?N21) mutant prevented Mo-bisPGD binding and resulted in a degenerate [3Fe-4S] cluster form of FS0 being assembled. DmsA belongs to the Type II subclass of Mo-bisPGD-containing catalytic subunits that is distinguished from the Type I subclass by having three rather than two residues between the first two Cys residues coordinating FS0 and a conserved Arg residue rather than a Lys residue following the fourth cluster coordinating Cys. We introduced a Type I Cys group into DmsA in two stages. We changed its sequence from (18)C(A)TVNC(B)GSRC(C)P(27) to (18)C(A)TYC(B)GVGC(C)G(26) (similar to that of formate dehydrogenase (FdnG)) and demonstrated that this eliminated both Mo-bisPGD binding and EPR-detectable FS0. We then combined this change with a DmsA(R61K) mutation and demonstrated that this additional change partially rescued Mo-bisPGD insertion.

SUBMITTER: Tang H

PROVIDER: S-EPMC3083165 | biostudies-literature | 2011 Apr

REPOSITORIES: biostudies-literature

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Correct assembly of iron-sulfur cluster FS0 into Escherichia coli dimethyl sulfoxide reductase (DmsABC) is a prerequisite for molybdenum cofactor insertion.

Tang Huipo H Rothery Richard A RA Voss James E JE Weiner Joel H JH

The Journal of biological chemistry 20110226 17

The FS0 [4Fe-4S] cluster of the catalytic subunit (DmsA) of Escherichia coli dimethyl sulfoxide reductase (DmsABC) plays a key role in the electron transfer relay. We have now established an additional role for the cluster in directing molybdenum cofactor assembly during enzyme maturation. EPR spectroscopy indicates that FS0 has a high spin ground state (S = 3/2) in its reduced form, resulting in an EPR spectrum with a peak at g ∼ 5.0. The cluster is predicted to be in close proximity to the mol ...[more]

PMID: 21357619

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Project description:The dimethyl sulfoxide reductase (or MopB) family is a diverse assemblage of enzymes found throughout Bacteria and Archaea. Many of these enzymes are believed to have been present in the last universal common ancestor (LUCA) of all cellular lineages. However, gaps in knowledge remain about how MopB enzymes evolved and how this diversification of functions impacted global biogeochemical cycles through geologic time. In this study, we perform maximum likelihood phylogenetic analyses on manually curated comparative genomic and metagenomic data sets containing over 47,000 distinct MopB homologs. We demonstrate that these enzymes constitute a catalytically and mechanistically diverse superfamily defined not by the molybdopterin- or tungstopterin-containing [molybdopterin or tungstopterin bis(pyranopterin guanine dinucleotide) (Mo/W-bisPGD)] cofactor but rather by the structural fold that binds it in the protein. Our results suggest that major metabolic innovations were the result of the loss of the metal cofactor or the gain or loss of protein domains. Phylogenetic analyses also demonstrated that formate oxidation and CO2 reduction were the ancestral functions of the superfamily, traits that have been vertically inherited from the LUCA. Nearly all of the other families, which drive all other biogeochemical cycles mediated by this superfamily, originated in the bacterial domain. Thus, organisms from Bacteria have been the key drivers of catalytic and biogeochemical innovations within the superfamily. The relative ordination of MopB families and their associated catalytic activities emphasize fundamental mechanisms of evolution in this superfamily. Furthermore, it underscores the importance of prokaryotic adaptability in response to the transition from an anoxic to an oxidized atmosphere. IMPORTANCE The MopB superfamily constitutes a repertoire of metalloenzymes that are central to enduring mysteries in microbiology, from the origin of life and how microorganisms and biogeochemical cycles have coevolved over deep time to how anaerobic life adapted to increasing concentrations of O2 during the transition from an anoxic to an oxic world. Our work emphasizes that phylogenetic analyses can reveal how domain gain or loss events, the acquisition of novel partner subunits, and the loss of metal cofactors can stimulate novel radiations of enzymes that dramatically increase the catalytic versatility of superfamilies. We also contend that the superfamily concept in protein evolution can uncover surprising kinships between enzymes that have remarkably different catalytic and physiological functions.

Dataset Information

Correct assembly of iron-sulfur cluster FS0 into Escherichia coli dimethyl sulfoxide reductase (DmsABC) is a prerequisite for molybdenum cofactor insertion.

Publications

Correct assembly of iron-sulfur cluster FS0 into Escherichia coli dimethyl sulfoxide reductase (DmsABC) is a prerequisite for molybdenum cofactor insertion.

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