Enzymes of hydrogen metabolism in Pyrococcus furiosus

• Type: Article in International Scientific Journal
• Date: 2000

Authors

Silva, PJ (Author) Other; van den Ban, ECD (Author) Other; Wassink, H (Author) Other; Haaker, H (Author) Other; de Castro, B (Author) FCUP; Robb, FT (Author) Other; Hagen, WR (Author) Other

Journal

Title: European Journal of Biochemistry

Vol. 267

Pages: 6541-6551

ISSN: 0014-2956

Publisher: Blackwell

Indexing

ISI Web of Knowledge - 98 Citations

Scopus - 87 Citations

Scientific classification

FOS: Natural sciences > Biological sciences

Other information

Authenticus ID: P-000-YJF

DOI: 10.1046/j.1432-1327.2000.01745.x

Abstract (EN): The genome of Pyrococcus furiosus contains the putative mbhABCDEFGHIJKLMN operon for a 14-subunit transmembrane complex associated with a Ni-Fe hydrogenase. Ten ORFs (mbhA-I and mbhM) encode hydrophobic, membrane-spanning subunits. Four ORFs (mbhJKL and mbhN) encode putative soluble proteins. Two of these correspond to the canonical small and large subunit of Ni-Fe hydrogenase, however, the small subunit can coordinate only a single iron-sulfur cluster, corresponding to the proximal [4Fe-4S] cubane. The structural genes for the small and the large subunits, mbhJ and mbhL, are separated in the genome by a third ORF, mbhK, encoding a protein of unknown function without Fe/S binding. The fourth ORF, mbhN, encodes a 2[4Fe-4S] protein. With P. furiosus soluble [4Fe-4S] ferredoxin as the electron donor the membranes produce H-2, and this activity is retained in an extracted core complex of the mbh operon when solubilized and partially purified under mild conditions. The properties of this membrane-bound hydrogenase are unique. It is rather resistant to inhibition by carbon monoxide. It also exhibits an extremely high ratio of H-2 evolution to H-2 uptake activity compared with other hydrogenases. The activity is sensitive to inhibition by dicyclohexylcarbodiimide, an inhibitor of NADH dehydrogenase (complex I). EPR of the reduced core complex is characteristic for interacting iron-sulfur clusters with E-m approximate to -0.33 V. The genome contains a second putative operon, mbxABCDFGHH'MJKLN, for a multisubunit transmembrane complex with strong homology to the mbh operon, however, with a highly unusual putative binding motif for the Ni-Fe-cluster in the large hydrogenase subunit. Kinetic studies of membrane-bound hydrogenase, soluble hydrogenase and sulfide dehydrogenase activities allow the formulation of a comprehensive working hypothesis of H-2 metabolism in P. furiosus in terms of three pools of reducing equivalents (ferredoxin, NADPH, H-2) connected by devices for transduction, transfer, recovery and safety-valving of energy.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11