Electrochemical Resolution of the [4Fe-4S] Centers of the AdoMet Radical Enzyme BtrN

Evidence of Proton Coupling and an Unusual, Low-Potential Auxiliary Cluster

Stephanie J. Maiocco, Tyler L. Grove, Squire J. Booker, Sean J. Elliott

Research output: Contribution to journalArticle

17 Citations (Scopus)

Abstract

The S-adenosylmethionine (AdoMet) radical superfamily of enzymes includes over 113 500 unique members, each of which contains one indispensable iron-sulfur (FeS) cluster that is required to generate a 5′-deoxyadenosyl 5′-radical intermediate during catalysis. Enzymes within several subgroups of the superfamily, however, have been found to contain one or more additional FeS clusters. While these additional clusters are absolutely essential for enzyme activity, their exact roles in the function and/or mechanism of action of many of the enzymes are at best speculative, indicating a need to develop methods to characterize and study these clusters in more detail. Here, BtrN, an AdoMet radical dehydrogenase that catalyzes the two-electron oxidation of 2-deoxy-scyllo-inosamine to amino-dideoxy-scyllo-inosose, an intermediate in the biosynthesis of 2-deoxystreptamine antibiotics, is examined through direct electrochemistry, where the potential of both its AdoMet radical and auxiliary [4Fe-4S] clusters can be measured simultaneously. We find that the AdoMet radical cluster exhibits a midpoint potential of -510 mV, while the auxiliary cluster exhibits a midpoint potential of -765 mV, to our knowledge the lowest [4Fe-4S]2+/+ potential to be determined to date. The impact of AdoMet binding and the pH dependence of catalysis are also quantitatively observed. These data show that direct electrochemical methods can be used to further elucidate the chemistry of the burgeoning AdoMet radical superfamily in the future.

Original languageEnglish (US)
Pages (from-to)8664-8667
Number of pages4
JournalJournal of the American Chemical Society
Volume137
Issue number27
DOIs
StatePublished - Jul 15 2015

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S-Adenosylmethionine
Protons
Enzymes
Catalysis
Biosynthesis
Enzyme activity
Electrochemistry
Antibiotics
Sulfur
Iron
Oxidation
Electrons
Oxidoreductases
Anti-Bacterial Agents

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

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title = "Electrochemical Resolution of the [4Fe-4S] Centers of the AdoMet Radical Enzyme BtrN: Evidence of Proton Coupling and an Unusual, Low-Potential Auxiliary Cluster",
abstract = "The S-adenosylmethionine (AdoMet) radical superfamily of enzymes includes over 113 500 unique members, each of which contains one indispensable iron-sulfur (FeS) cluster that is required to generate a 5′-deoxyadenosyl 5′-radical intermediate during catalysis. Enzymes within several subgroups of the superfamily, however, have been found to contain one or more additional FeS clusters. While these additional clusters are absolutely essential for enzyme activity, their exact roles in the function and/or mechanism of action of many of the enzymes are at best speculative, indicating a need to develop methods to characterize and study these clusters in more detail. Here, BtrN, an AdoMet radical dehydrogenase that catalyzes the two-electron oxidation of 2-deoxy-scyllo-inosamine to amino-dideoxy-scyllo-inosose, an intermediate in the biosynthesis of 2-deoxystreptamine antibiotics, is examined through direct electrochemistry, where the potential of both its AdoMet radical and auxiliary [4Fe-4S] clusters can be measured simultaneously. We find that the AdoMet radical cluster exhibits a midpoint potential of -510 mV, while the auxiliary cluster exhibits a midpoint potential of -765 mV, to our knowledge the lowest [4Fe-4S]2+/+ potential to be determined to date. The impact of AdoMet binding and the pH dependence of catalysis are also quantitatively observed. These data show that direct electrochemical methods can be used to further elucidate the chemistry of the burgeoning AdoMet radical superfamily in the future.",
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Electrochemical Resolution of the [4Fe-4S] Centers of the AdoMet Radical Enzyme BtrN : Evidence of Proton Coupling and an Unusual, Low-Potential Auxiliary Cluster. / Maiocco, Stephanie J.; Grove, Tyler L.; Booker, Squire J.; Elliott, Sean J.

In: Journal of the American Chemical Society, Vol. 137, No. 27, 15.07.2015, p. 8664-8667.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Electrochemical Resolution of the [4Fe-4S] Centers of the AdoMet Radical Enzyme BtrN

T2 - Evidence of Proton Coupling and an Unusual, Low-Potential Auxiliary Cluster

AU - Maiocco, Stephanie J.

AU - Grove, Tyler L.

AU - Booker, Squire J.

AU - Elliott, Sean J.

PY - 2015/7/15

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N2 - The S-adenosylmethionine (AdoMet) radical superfamily of enzymes includes over 113 500 unique members, each of which contains one indispensable iron-sulfur (FeS) cluster that is required to generate a 5′-deoxyadenosyl 5′-radical intermediate during catalysis. Enzymes within several subgroups of the superfamily, however, have been found to contain one or more additional FeS clusters. While these additional clusters are absolutely essential for enzyme activity, their exact roles in the function and/or mechanism of action of many of the enzymes are at best speculative, indicating a need to develop methods to characterize and study these clusters in more detail. Here, BtrN, an AdoMet radical dehydrogenase that catalyzes the two-electron oxidation of 2-deoxy-scyllo-inosamine to amino-dideoxy-scyllo-inosose, an intermediate in the biosynthesis of 2-deoxystreptamine antibiotics, is examined through direct electrochemistry, where the potential of both its AdoMet radical and auxiliary [4Fe-4S] clusters can be measured simultaneously. We find that the AdoMet radical cluster exhibits a midpoint potential of -510 mV, while the auxiliary cluster exhibits a midpoint potential of -765 mV, to our knowledge the lowest [4Fe-4S]2+/+ potential to be determined to date. The impact of AdoMet binding and the pH dependence of catalysis are also quantitatively observed. These data show that direct electrochemical methods can be used to further elucidate the chemistry of the burgeoning AdoMet radical superfamily in the future.

AB - The S-adenosylmethionine (AdoMet) radical superfamily of enzymes includes over 113 500 unique members, each of which contains one indispensable iron-sulfur (FeS) cluster that is required to generate a 5′-deoxyadenosyl 5′-radical intermediate during catalysis. Enzymes within several subgroups of the superfamily, however, have been found to contain one or more additional FeS clusters. While these additional clusters are absolutely essential for enzyme activity, their exact roles in the function and/or mechanism of action of many of the enzymes are at best speculative, indicating a need to develop methods to characterize and study these clusters in more detail. Here, BtrN, an AdoMet radical dehydrogenase that catalyzes the two-electron oxidation of 2-deoxy-scyllo-inosamine to amino-dideoxy-scyllo-inosose, an intermediate in the biosynthesis of 2-deoxystreptamine antibiotics, is examined through direct electrochemistry, where the potential of both its AdoMet radical and auxiliary [4Fe-4S] clusters can be measured simultaneously. We find that the AdoMet radical cluster exhibits a midpoint potential of -510 mV, while the auxiliary cluster exhibits a midpoint potential of -765 mV, to our knowledge the lowest [4Fe-4S]2+/+ potential to be determined to date. The impact of AdoMet binding and the pH dependence of catalysis are also quantitatively observed. These data show that direct electrochemical methods can be used to further elucidate the chemistry of the burgeoning AdoMet radical superfamily in the future.

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