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 language | English (US) |
|---|---|
| Pages (from-to) | 6050-6053 |
| Number of pages | 4 |
| Journal | Biochemistry |
| Volume | 57 |
| Issue number | 42 |
| DOIs | |
| State | Published - Oct 23 2018 |
| Externally published | Yes |
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ASJC Scopus subject areas
- Biochemistry
Cite this
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 journal › Article
}
TY - JOUR
T1 - Deconvoluting the Reduction Potentials for the Three [4Fe-4S] Clusters in an AdoMet Radical SCIFF Maturase
AU - Walker, Lindsey M.
AU - Kincannon, William M.
AU - Bandarian, Vahe
AU - Elliott, Sean J.
PY - 2018/10/23
Y1 - 2018/10/23
N2 - 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.
AB - 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.
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U2 - 10.1021/acs.biochem.8b00846
DO - 10.1021/acs.biochem.8b00846
M3 - Article
VL - 57
SP - 6050
EP - 6053
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 42
ER -