Oxygen-tolerant [NiFe]-hydrogenases: the individual and collective importance of supernumerary cysteines at the proximal Fe-S cluster

TY - JOUR

T1 - Oxygen-tolerant [NiFe]-hydrogenases

T2 - the individual and collective importance of supernumerary cysteines at the proximal Fe-S cluster

AU - Lukey, Michael J

AU - Roessler, Maxie M

AU - Parkin, Alison

AU - Evans, Rhiannon M

AU - Davies, Rosalind A

AU - Lenz, Oliver

AU - Friedrich, Baerbel

AU - Sargent, Frank

AU - Armstrong, Fraser A

PY - 2011/10/26

Y1 - 2011/10/26

N2 - An important clue to the mechanism for O(2) tolerance of certain [NiFe]-hydrogenases is the conserved presence of a modified environment around the iron-sulfur cluster that is proximal to the active site. The O(2)-tolerant enzymes contain two cysteines, located at opposite ends of this cluster, which are glycines in their O(2)-sensitive counterparts. The strong correlation highlights special importance for electron-transfer activity in the protection mechanism used to combat O(2). Site-directed mutagenesis has been carried out on Escherichia coli hydrogenase-1 to substitute these cysteines (C19 and C120) individually and collectively for glycines, and the effects of each replacement have been determined using protein film electrochemistry and electron paramagnetic resonance (EPR) spectroscopy. The "split" iron-sulfur cluster EPR signal thus far observed when oxygen-tolerant [NiFe]-hydrogenases are subjected to oxidizing potentials is found not to provide any simple, reliable correlation with oxygen tolerance. Oxygen tolerance is largely conferred by a single cysteine (C19), replacement of which by glycine removes the ability to function even in 1% O(2).

AB - An important clue to the mechanism for O(2) tolerance of certain [NiFe]-hydrogenases is the conserved presence of a modified environment around the iron-sulfur cluster that is proximal to the active site. The O(2)-tolerant enzymes contain two cysteines, located at opposite ends of this cluster, which are glycines in their O(2)-sensitive counterparts. The strong correlation highlights special importance for electron-transfer activity in the protection mechanism used to combat O(2). Site-directed mutagenesis has been carried out on Escherichia coli hydrogenase-1 to substitute these cysteines (C19 and C120) individually and collectively for glycines, and the effects of each replacement have been determined using protein film electrochemistry and electron paramagnetic resonance (EPR) spectroscopy. The "split" iron-sulfur cluster EPR signal thus far observed when oxygen-tolerant [NiFe]-hydrogenases are subjected to oxidizing potentials is found not to provide any simple, reliable correlation with oxygen tolerance. Oxygen tolerance is largely conferred by a single cysteine (C19), replacement of which by glycine removes the ability to function even in 1% O(2).

UR - http://www.scopus.com/inward/record.url?scp=80054971344&partnerID=8YFLogxK

U2 - 10.1021/ja205393w

DO - 10.1021/ja205393w

M3 - Article

C2 - 21916508

SN - 1520-5126

VL - 133

SP - 16881

EP - 16892

JO - Journal of the American Chemical Society

JF - Journal of the American Chemical Society

IS - 42

ER -