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PLoS One. 2009 Oct 26;4(10):e7565. doi: 10.1371/journal.pone.0007565.

Tyrosine, cysteine, and S-adenosyl methionine stimulate in vitro [FeFe] hydrogenase activation.

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  • 1Department of Chemical Engineering, Stanford University, Stanford, California, United States of America.

Abstract

BACKGROUND:

[FeFe] hydrogenases are metalloenzymes involved in the anaerobic metabolism of H(2). These proteins are distinguished by an active site cofactor known as the H-cluster. This unique [6Fe-6S] complex contains multiple non-protein moieties and requires several maturation enzymes for its assembly. The pathways and biochemical precursors for H-cluster biosynthesis have yet to be elucidated.

PRINCIPAL FINDINGS:

We report an in vitro maturation system in which, for the first time, chemical additives enhance [FeFe] hydrogenase activation, thus signifying in situ H-cluster biosynthesis. The maturation system is comprised of purified hydrogenase apoprotein; a dialyzed Escherichia coli cell lysate containing heterologous HydE, HydF, and HydG maturases; and exogenous small molecules. Following anaerobic incubation of the Chlamydomonas reinhardtii HydA1 apohydrogenase with S-adenosyl methionine (SAM), cysteine, tyrosine, iron, sulfide, and the non-purified maturases, hydrogenase activity increased 5-fold relative to incubations without the exogenous substrates. No conditions were identified in which addition of guanosine triphosphate (GTP) improved hydrogenase maturation.

SIGNIFICANCE:

The in vitro system allows for direct investigation of [FeFe] hydrogenase activation. This work also provides a foundation for studying the biosynthetic mechanisms of H-cluster biosynthesis using solely purified enzymes and chemical additives.

PMID:
19855833
[PubMed - indexed for MEDLINE]
PMCID:
PMC2762031
Free PMC Article

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