Open AccessFunctional and Structural Role of the Cytochrome b Subunit of the Membrane‐Bound Hydrogenase Complex of Alcaligenes Eutrophus H16
Author(s) -
Bernhard Michael,
Benelli Bruna,
Hochkoeppler Alejandro,
Zani Davide,
Friedrich Barbel
Publication year - 1997
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1997.00179.x
Subject(s) - hydrogenase , protein subunit , cytochrome , chemistry , alcaligenes , biochemistry , stereochemistry , enzyme , biology , gene , bacteria , genetics , pseudomonas
This study shows that the product of the hoxZ gene of Alcaligenes eutrophus HI6 is a b ‐type cytochrome (cytochrome b z , which is essential for anchoring the membrane‐bound hydrogenase (MBH) complex to the periplasmic side of the membrane and for H 2 ‐coupled respiration. The hoxZ product is not required for MBH translocation and H 2 ‐dependent reduction of the redox dye, 2,3,5‐triphenyl‐2‐tetrazolium chloride. The lack of cytochrome b z does not affect the electron‐transport activities linked to oxidation of succinate and NADH, although it enhances the electron‐flow rate through the cytochrome‐c oxidase pathway in hoxZδ membranes. We show that the hoxZ product is a dihaem cytochrome b (haems with of E m7.0 + 10 mV and + 166 mV) involved in H 2 ‐dependent electron transfer. We conclude that cytochrome b z , of the A. eutrophus MBH complex is the link necessary for transfer of electrons from H 2 to the ubiquinone pool and that it is required for attachment of MBH to the membrane.