Structure of the non-redox-active tungsten/[4Fe:4S] enzyme acetylene hydratase

Proc Natl Acad Sci U S A. 2007 Feb 27;104(9):3073-7. doi: 10.1073/pnas.0610407104.

Abstract

The tungsten-iron-sulfur enzyme acetylene hydratase stands out from its class because it catalyzes a nonredox reaction, the hydration of acetylene to acetaldehyde. Sequence comparisons group the protein into the dimethyl sulfoxide reductase family, and it contains a bis-molybdopterin guanine dinucleotide-ligated tungsten atom and a cubane-type [4Fe:4S] cluster. The crystal structure of acetylene hydratase at 1.26 A now shows that the tungsten center binds a water molecule that is activated by an adjacent aspartate residue, enabling it to attack acetylene bound in a distinct, hydrophobic pocket. This mechanism requires a strong shift of pK(a) of the aspartate, caused by a nearby low-potential [4Fe:4S] cluster. To access this previously unrecognized W-Asp active site, the protein evolved a new substrate channel distant from where it is found in other molybdenum and tungsten enzymes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Binding Sites / genetics
  • Crystallization
  • Deltaproteobacteria / chemistry*
  • Hydro-Lyases / chemistry*
  • Models, Molecular*
  • Static Electricity
  • Tungsten / chemistry

Substances

  • Hydro-Lyases
  • acetylene hydratase
  • Tungsten

Associated data

  • PDB/2E7Z