Maturation of Hydrogenases

Book · Sun Jan 01 04:00:00 EST 2006

OSTI ID:944460

Bock, A; King, P W; Blokesch, M; Posewitz, M C

Enzymes possessing the capacity to oxidize molecular hydrogen have developed convergently three class of enzymes leading to: [FeFe]-, [NiFe]-, and [FeS]-cluster-free hydrogenases. They differ in the composition and the structure of the active site metal centre and the sequence of the constituent structural polypeptides but they show one unifying feature, namely the existence of CN and/or CO ligands at the active site Fe. Recent developments in the analysis of the maturation of [FeFe]- and [NiFe]- hydrogenases have revealed a remarkably complex pattern of mostly novel biochemical reactions. Maturation of [FeFe]-hydrogenases requires a minimum of three auxiliary proteins, two of which belong to the class of Radical-SAM enzymes and other to the family of GTPases. They are sufficient to generate active enzyme when their genes are co-expressed with the structural genes in a heterologous host, otherwise deficient in [FeFe]-hydrogenase expression. Maturation of the large subunit of [NiFe]-hydrogenases depends on the activity of at least seven core proteins that catalyze the synthesis of the CN ligand, have a function in the coordination of the active site iron, the insertion of nickel and the proteolytic maturation of the large subunit. Whereas this core maturation machinery is sufficient to generate active hydrogenase in the cytoplasm, like that of hydrogenase 3 from Escherichia coli, additional proteins are involved in the export of the ready-assembled heterodimeric enzyme to the periplasm via the twin-arginine translocation system in the case of membrane-bound hydrogenases. A series of other gene products with intriguing putative functions indicate that the minimal pathway established for E. coli [NiFe]-hydrogenase maturation may possess even higher complexity in other organisms.

• Research Organization: National Renewable Energy Laboratory (NREL), Golden, CO.
• Sponsoring Organization: USDOE
• DOE Contract Number: AC36-99GO10337
• OSTI ID: 944460
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
59 BASIC BIOLOGICAL SCIENCES
CAPACITY
CYTOPLASM
ENZYMES
ESCHERICHIA COLI
EXPORTS
GENES
HYDROGEN
HYDROGENASES
Hydrogen
IRON
MACHINERY
NICKEL
POLYPEPTIDES
PROTEINS
SYNTHESIS
TRANSLOCATION