1ru3
|
Crystal Structure of the monomeric acetyl-CoA synthase from Carboxydothermus hydrogenoformans
OverviewOverview
In anaerobic microorganisms employing the acetyl-CoA pathway, acetyl-CoA, synthase (ACS) and CO dehydrogenase (CODH) form a complex (ACS/CODH) that, catalyzes the synthesis of acetyl-CoA from CO, a methyl group, and CoA., Previously, a [4Fe-4S] cubane bridged to a copper-nickel binuclear site, (active site cluster A of the ACS component) was identified in the, ACS(Mt)/CODH(Mt) from Moorella thermoacetica whereas another study, revealed a nickel-nickel site in the open form of ACS(Mt), and a, zink-nickel site in the closed form. The ACS(Ch) of the hydrogenogenic, bacterium Carboxydothermus hydrogenoformans was found to exist as an, 82.2-kDa monomer as well as in a 1:1 molar complex with the 73.3-kDa, CODHIII(Ch). Homogeneous ACS(Ch) and ACS(Ch)/CODHIII(Ch) catalyzed the, exchange between [1-(14)C]acetyl-CoA and (12)CO with specific activities, of 2.4 or 5.9 micromol of CO per min per mg, respectively, at 70 degrees C, and pH 6.0. They also catalyzed the synthesis of acetyl-CoA from CO, methylcobalamin, corrinoid iron-sulfur protein, and CoA with specific, activities of 0.14 or 0.91 micromol of acetyl-CoA formed per min per mg, respectively, at 70 degrees C and pH 7.3. The functional cluster A of, ACS(Ch) contains a Ni-Ni-[4Fe-4S] site, in which the positions proximal, and distal to the cubane are occupied by Ni ions. This result is apparent, from a positive correlation of the Ni contents and negative correlations, of the Cu or Zn contents with the acetyl-CoA/CO exchange activities of, different preparations of monomeric ACS(Ch), a 2.2-A crystal structure of, the dithionite-reduced monomer in an open conformation, and x-ray, absorption spectroscopy.
About this StructureAbout this Structure
1RU3 is a Single protein structure of sequence from Carboxydothermus hydrogenoformans with NI, SF4 and GOL as ligands. Full crystallographic information is available from OCA.
ReferenceReference
A functional Ni-Ni-[4Fe-4S] cluster in the monomeric acetyl-CoA synthase from Carboxydothermus hydrogenoformans., Svetlitchnyi V, Dobbek H, Meyer-Klaucke W, Meins T, Thiele B, Romer P, Huber R, Meyer O, Proc Natl Acad Sci U S A. 2004 Jan 13;101(2):446-51. Epub 2003 Dec 29. PMID:14699043
Page seeded by OCA on Sat Nov 24 23:16:12 2007