Ligand-induced conformational changes within a hexameric Acyl-CoA thioesterase

J Biol Chem. 2011 Oct 14;286(41):35643-35649. doi: 10.1074/jbc.M111.225953. Epub 2011 Aug 17.

Abstract

Acyl-coenzyme A (acyl-CoA) thioesterases play a crucial role in the metabolism of activated fatty acids, coenzyme A, and other metabolic precursor molecules including arachidonic acid and palmitic acid. These enzymes hydrolyze coenzyme A from acyl-CoA esters to mediate a range of cellular functions including β-oxidation, lipid biosynthesis, and signal transduction. Here, we present the crystal structure of a hexameric hot-dog domain-containing acyl-CoA thioesterase from Bacillus halodurans in the apo-form and provide structural and comparative analyses to the coenzyme A-bound form to identify key conformational changes induced upon ligand binding. We observed dramatic ligand-induced changes at both the hot-dog dimer and the trimer-of-dimer interfaces; the dimer interfaces in the apo-structure differ by over 20% and decrease to about half the size in the ligand-bound state. We also assessed the specificity of the enzyme against a range of fatty acyl-CoA substrates and have identified a preference for short-chain fatty acyl-CoAs. Coenzyme A was shown both to negatively regulate enzyme activity, representing a direct inhibitory feedback, and consistent with the structural data, to destabilize the quaternary structure of the enzyme. Coenzyme A-induced conformational changes in the C-terminal helices of enzyme were assessed through mutational analysis and shown to play a role in regulating enzyme activity. The conformational changes are likely to be conserved from bacteria through to humans and provide a greater understanding, particularly at a structural level, of thioesterase function and regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacillus / enzymology*
  • Bacterial Proteins / chemistry*
  • Bacterial Proteins / metabolism
  • Coenzyme A / chemistry*
  • Coenzyme A / metabolism
  • Fatty Acids / chemistry
  • Fatty Acids / metabolism
  • Humans
  • Ligands
  • Palmitoyl-CoA Hydrolase / chemistry*
  • Palmitoyl-CoA Hydrolase / metabolism
  • Protein Multimerization / physiology*
  • Protein Structure, Quaternary
  • Protein Structure, Secondary
  • Substrate Specificity

Substances

  • Bacterial Proteins
  • Fatty Acids
  • Ligands
  • Palmitoyl-CoA Hydrolase
  • Coenzyme A

Associated data

  • PDB/3SPS