Open AccessTracing the incorporation of the “ninth sulfur” into the nitrogenase cofactor precursor with selenite and tellurite
Author(s) -
Kazuki Tanifuji,
Andrew J. Jasniewski,
David Villarreal,
Martin T. Stiebritz,
Chi Chung Lee,
Jarett Wilcoxen,
Yasuhiro Okhi,
Ruchira Chatterjee,
Isabel Bogacz,
Junko Yano,
Jan Kern,
Britt Hedman,
Keith O. Hodgson,
R. David Britt,
Yilin Hu,
Markus W. Ribbe
Publication year - 2021
Publication title -
nature chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 9.996
H-Index - 232
eISSN - 1755-4349
pISSN - 1755-4330
DOI - 10.1038/s41557-021-00799-8
Subject(s) - chemistry , nitrogenase , sulfur , molybdenum , cluster (spacecraft) , cofactor , iron–sulfur cluster , photochemistry , stereochemistry , inorganic chemistry , nitrogen fixation , nitrogen , enzyme , biochemistry , organic chemistry , computer science , programming language
Molybdenum nitrogenase catalyses the reduction of N 2 to NH 3 at its cofactor, an [(R-homocitrate)MoFe 7 S 9 C] cluster synthesized via the formation of a [Fe 8 S 9 C] L-cluster prior to the insertion of molybdenum and homocitrate. We have previously identified a [Fe 8 S 8 C] L*-cluster, which is homologous to the core structure of the L-cluster but lacks the 'ninth sulfur' in the belt region. However, direct evidence and mechanistic details of the L*- to L-cluster conversion upon 'ninth sulfur' insertion remain elusive. Here we trace the 'ninth sulfur' insertion using SeO 3 2- and TeO 3 2- as 'labelled' SO 3 2- . Biochemical, electron paramagnetic resonance and X-ray absorption spectroscopy/extended X-ray absorption fine structure studies suggest a role of the 'ninth sulfur' in cluster transfer during cofactor biosynthesis while revealing the incorporation of Se 2- - and Te 2- -like species into the L-cluster. Density functional theory calculations further point to a plausible mechanism involving in situ reduction of SO 3 2- to S 2- , thereby suggesting the utility of this reaction to label the catalytically important belt region for mechanistic investigations of nitrogenase.