Electron Paramagnetic Resonance Characterization of Three Iron-Sulfur Clusters Present in the Nitrogenase Cofactor Maturase NifB from Methanocaldococcus infernus.
J Am Chem Soc
; 138(24): 7468-71, 2016 06 22.
Article
in En
| MEDLINE
| ID: mdl-27268267
ABSTRACT
NifB utilizes two equivalents of S-adenosyl methionine (SAM) to insert a carbide atom and fuse two substrate [Fe-S] clusters forming the NifB cofactor (NifB-co), which is then passed to NifEN for further modification to form the iron-molybdenum cofactor (FeMo-co) of nitrogenase. Here, we demonstrate that NifB from the methanogen Methanocaldococcus infernus is a radical SAM enzyme able to reductively cleave SAM to 5'-deoxyadenosine radical and is competent in FeMo-co maturation. Using electron paramagnetic resonance spectroscopy we have characterized three [4Fe-4S] clusters, one SAM binding cluster, and two auxiliary clusters probably acting as substrates for NifB-co formation. Nitrogen coordination to one or more of the auxiliary clusters in NifB was observed, and its mechanistic implications for NifB-co dissociation from the maturase are discussed.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
S-Adenosylmethionine
/
Bacterial Proteins
/
Iron Compounds
/
Methanocaldococcus
/
Nitrogenase
Language:
En
Journal:
J Am Chem Soc
Year:
2016
Document type:
Article
Affiliation country:
Estados Unidos