Deconvoluting the Reduction Potentials for the Three [4Fe-4S] Clusters in an AdoMet Radical SCIFF Maturase

Lindsey M. Walker, William M. Kincannon, Vahe Bandarian, Sean J. Elliott

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Enzymes in the S-adenosyl-l-methionine (AdoMet) radical enzyme superfamily are metalloenzymes that catalyze a wide variety of complex radical-mediated transformations with the aid of a [4Fe-4S] cluster, which is required for activation of AdoMet to generate the 5′-deoxyadenosyl radical to initiate the catalytic cycle. In addition to this cluster, some enzymes share an additional domain, the SPASM domain, that houses auxiliary FeS clusters whose functional significance is not clearly understood. The AdoMet radical enzyme Tte1186, which catalyzes a thioether cross-link in a cysteine rich peptide (SCIFF), has two auxiliary [4Fe-4S] clusters within a SPASM domain that are required for enzymatic activity but not for the generation of the 5′-deoxyadenosyl radical intermediate. Here we demonstrate the ability to measure independently the midpoint potentials of each of the three [4Fe-4S] clusters by employing Tte1186 variants for which only the first, second, or AdoMet binding cluster is bound. This allows, for the first time, assignment of reduction potentials for all clusters in an AdoMet radical enzyme with a SPASM domain. Our results show that the clusters have midpoint potentials that are within 100 mV of each other, suggesting that their electrochemical properties are not greatly influenced by the presence of the nearby clusters.

Original languageEnglish (US)
Pages (from-to)6050-6053
Number of pages4
JournalBiochemistry
Volume57
Issue number42
DOIs
StatePublished - Oct 23 2018
Externally publishedYes

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Methionine
Enzymes
Sulfides
Electrochemical properties
Cysteine
Chemical activation
Peptides

ASJC Scopus subject areas

  • Biochemistry

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Deconvoluting the Reduction Potentials for the Three [4Fe-4S] Clusters in an AdoMet Radical SCIFF Maturase. / Walker, Lindsey M.; Kincannon, William M.; Bandarian, Vahe; Elliott, Sean J.

In: Biochemistry, Vol. 57, No. 42, 23.10.2018, p. 6050-6053.

Research output: Contribution to journalArticle

Walker, Lindsey M. ; Kincannon, William M. ; Bandarian, Vahe ; Elliott, Sean J. / Deconvoluting the Reduction Potentials for the Three [4Fe-4S] Clusters in an AdoMet Radical SCIFF Maturase. In: Biochemistry. 2018 ; Vol. 57, No. 42. pp. 6050-6053.
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