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A glycyl free radical as the precursor in the synthesis of carbon monoxide and cyanide by the [FeFe]‐hydrogenase maturase HydG
Author(s) -
Nicolet Yvain,
Martin Lydie,
Tron Cécile,
Fontecilla-Camps Juan C.
Publication year - 2010
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2010.09.008
Subject(s) - chemistry , cyanide , hydrogenase , stereochemistry , carbon monoxide , serine , catalysis , enzyme , biochemistry , organic chemistry
HydG uses tyrosine to synthesize the CN − /CO ligands of [FeFe]‐hydrogenase active site. We have mutated two of the [4Fe–4S]‐cluster cysteine ligands of the HydG C‐terminal domain (CTD) to serine. The double mutant can still synthesize CN − but not CO. In a mutant lacking the CTD both CN − and CO synthesis are abolished. Like in ThiH, the initial steps of CN − synthesis are carried out in the TIM‐barrel domain of HydG but some component(s) of the CTD are later needed. The mutants indicate that CO synthesis is metal‐based and occurs in the CTD. We postulate that CN − /CO synthesis is initiated by H 2 N–CH–CO 2 ‐Fragmentation of this radical into H 2 N–CH 2 and CO 2 or H 2 CNH and·CO 2 ‐provides plausible precursors for CN − /CO synthesis.