H₂

heterodisulfide oxidoreductase complex from Methanobacterium thermoautotrophicum Composition and properties

verfasst von

Edgar Setzke, Reiner Hedderich, Stefanie Heiden, Rudolf K. Thauer

Abstract

The reduction of the heterodisulfide (CoM‐S‐S‐HTP) of coenzyme M (H‐S‐CoM) and N‐7‐mercaptoheptanoylthreonine phosphate (H‐S‐HTP) with H₂ is an energy‐conserving step in most methanogenic Archaea. In this study, we show that in Methanobacterium thermoautotrophicum (strain Marburg) this reaction is catalyzed by a stable H₂: heterodisulfide oxidoreductase complex of F₄₂₀‐non‐reducing hydrogenase and heterodisulfide reductase. This complex, which was loosely associated with the cytoplasmic membrane, was purified 17‐fold with 80% yield to apparent homogeneity. The purified complex was composed of six different subunits of apparent molecular masses 80, 51, 41, 36, 21 and 17 kDa, and 1 mol complex, with apparent molecular mass 250 kDa, contained approximately 0.6 mol nickel, 0.9 mol FAD, 26 mol non‐heme iron and 22 mol acid‐labile sulfur. In 25 nM Chaps, the complex partially dissociated into two subcomplexes. The first subcomplex was was composed of the 51‐, 41‐ and 17‐kDa subunits; 1 mol trimer contained 0.7 mol nickel, 10 mol non‐heme iron and 9 mol acid‐labile sulfur and exhibited F₄₂₀‐non‐reducing hydrogenase activity. The other subcomplex was composed of the 80‐, 36‐ and 21‐kDa subunits; 1 mol trimer contained 0.8 mol FAD, 22 mol non‐heme iron and 15 mol acid‐labile sulfur and exhibited heterodisulfide‐reductase activity. The stimulatory effects of potassium phosphate, a membrane component, uracil derivatives and coenzyme F₄₃₀ on the H₂:heterodisulfide‐oxidoreductase activity of the purified complex are described.

Externe Organisation(en)

Philipps-Universität Marburg
Max-Planck-Institut für terrestrische Mikrobiologie

Typ

Artikel

Journal

European Journal of Biochemistry

Band

220

Seiten

139-148

Anzahl der Seiten

10

ISSN

0014-2956

Publikationsdatum

02.1994

Publikationsstatus

Veröffentlicht

Peer-reviewed

Ja

ASJC Scopus Sachgebiete

Biochemie

Elektronische Version(en)

https://doi.org/10.1111/j.1432-1033.1994.tb18608.x (Zugang: Offen)