Heterodisulfide reductase from Methanothermobacter marburgensis contains an active‐site [4Fe–4S] cluster that is directly involved in mediating heterodisulfide reduction

FEBS Letters

Johnson, Michael K²  Madadi-Kahkesh, Shahla¹  Clay, Michael D²  Duin, Evert C¹  Hedderich, Reiner¹ 

[1]Max-Planck-Institut für terrestrische Mikrobiologie and Laboratorium für Mikrobiologie, Fachbereich Biologie, Philipps-Universität, Karl-von-Frisch-Strasse, D-35043 Marburg, Germany

[2]Department of Chemistry and Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA

关键词: Heterodisulfide reductase;    Iron–sulfur protein;    Magnetic circular dichroism;    Ferredoxin:thioredoxin reductase;    Methanothermobacter marburgensis;    HDR;    heterodisulfide reductase;    CoM-SH;    coenzyme M or 2-mercaptoethane sulfonate;    CoB-SH;    coenzyme B or 7-mercaptoheptanoylthreonine phosphate;    CoM-S–S-CoB;    heterodisulfide of CoM-SH and CoB-SH;    CoM-HDR;    oxidized HDR incubated with CoM-SH;    CoB-HDR;    oxidized HDR incubated with CoB-SH;    FTR;    ferredoxin:thioredoxin reductase;    NEM-FTR;    N-ethylmaleimide-modified FTR;    VTMCD;    variable-temperature magnetic circular dichroism;    DTT;    dithiothreitol;   

DOI  :  10.1016/S0014-5793(02)02281-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Heterodisulfide reductases (HDRs) from methanogenic archaea are iron–sulfur flavoproteins or hemoproteins that catalyze the reversible reduction of the heterodisulfide (CoM-S–S-CoB) of the methanogenic thiol coenzymes, coenzyme M (CoM-SH) and coenzyme B (CoB-SH). In this work, the ground- and excited-state electronic properties of the paramagnetic Fe–S clusters in Methanothermobacter marburgensis HDR have been characterized using the combination of electron paramagnetic resonance and variable-temperature magnetic circular dichroism spectroscopies. The results confirm multiple S=1/2 [4Fe–4S]⁺ clusters in dithionite-reduced HDR and reveal spectroscopically distinct S=1/2 [4Fe–4S]³⁺ clusters in oxidized HDR samples treated separately with the CoM-SH and CoB-SH cosubstrates. The active site of HDR is therefore shown to contain a [4Fe–4S] cluster that is directly involved in mediating heterodisulfide reduction. The catalytic mechanism of HDR is discussed in light of the crystallographic and spectroscopic studies of the related chloroplast ferredoxin:thioredoxin reductase class of disulfide reductases.

【 授权许可】

Unknown