Coenzyme M binds to a [4Fe-4S] cluster in the active site of heterodisulfide reductase as deduced from EPR studies with the [33S]coenzyme M-treated enzyme

FEBS Lett. 2003 Mar 13;538(1-3):81-4. doi: 10.1016/s0014-5793(03)00134-0.

Abstract

Heterodisulfide reductase (Hdr) from methanogenic Archaea catalyzes the reversible reduction of the heterodisulfide (CoM-S-S-CoB) of the methanogenic thiol coenzymes, coenzyme M (CoM-SH) and coenzyme B (CoB-SH). Upon reaction of the oxidized enzyme with CoM-SH a unique paramagnetic species is formed, which has been shown to be due to a novel type of [4Fe-4S](3+) cluster. In this work, it was addressed whether CoM-SH is directly attached to this [4Fe-4S] cluster using CoM-(33)SH as substrate and purified Hdr from Methanothermobacter marburgensis and Methanosarcina barkeri. With both enzymes treatment with CoM-(33)SH in the presence of duroquinone as an oxidant resulted in a significant broadening of the electron paramagnetic resonance spectrum as compared to CoM-SH as substrate. The signal broadening resulted from an unresolved anisotropic hyperfine coupling between the (33)S nucleus and the paramagnetic center. The results provide compelling evidence for a direct binding of CoM-SH to the [4Fe-4S] cluster in the active site of the enzyme.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites
  • Electron Spin Resonance Spectroscopy
  • Iron-Sulfur Proteins / metabolism*
  • Mesna / metabolism*
  • Oxidoreductases / chemistry
  • Oxidoreductases / metabolism*
  • Substrate Specificity
  • Sulfur Isotopes

Substances

  • Iron-Sulfur Proteins
  • Sulfur Isotopes
  • Oxidoreductases
  • heterodisulfide reductase
  • Mesna