title: Inactivation of acetyl-CoA synthase/carbon monoxide dehydrogenase by copper.
abstract: Two recent crystal structures of acetyl-CoA synthase (ACS) from Moorella thermoacetica exhibited different metal contents and geometries at their active site, called the A-cluster. This led to the proposal of two catalytic mechanisms, one Ni-based, the other Cu-based. ACS was studied with respect to synthase activity, methyl group transfer activity, metal content, and EPR spectroscopy. Our results indicate that Cu is not required for catalysis and that it inactivates ACS by binding to the proximal site of the A-cluster. With Cu in this site, the A-cluster cannot accept a methyl group from the corrinoid-iron-sulfur protein, nor can it exhibit the NiFeC EPR signal after treatment with CO.
authors.affiliation: Department of Biochemistry and Biophysics, Texas A&M University, College Station, Texas 77843, USA.
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Bramlett
authors.forename: Xiangshi
authors.initials: X
authors.lastname: Tan
authors.forename: Paul A
authors.initials: PA
authors.lastname: Lindahl
mesh_terms: D000106:Acetate-CoA Ligase / Q000737:chemistry* / Q000378:metabolism; D003300:Copper / Q000737:chemistry*; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation; D016937:Gram-Positive Endospore-Forming Rods / Q000201:enzymology; D009532:Nickel / Q000737:chemistry
chemical_list: D003300:Copper; D009532:Nickel; D000106:Acetate-CoA Ligase