Deconvoluting the Reduction Potentials for the Three [4Fe-4S] Clusters in an AdoMet Radical SCIFF Maturase.
Biochemistry
; 57(42): 6050-6053, 2018 10 23.
Article
em En
| MEDLINE
| ID: mdl-30272955
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.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
S-Adenosilmetionina
/
Proteínas de Bactérias
/
Firmicutes
/
Proteínas Ferro-Enxofre
Idioma:
En
Revista:
Biochemistry
Ano de publicação:
2018
Tipo de documento:
Article
País de afiliação:
Estados Unidos