Novel domain arrangement in the crystal structure of a truncated acetyl-CoA synthase from Moorella thermoacetica.
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Ni-dependent acetyl-CoA synthase (ACS) and CO dehydrogenase (CODH) constitute the central enzyme complex of the Wood-Ljungdahl pathway of acetyl-CoA formation. The crystal structure of a recombinant bacterial ACS lacking the N-terminal domain that interacts with CODH shows a large reorganization of the remaining two globular domains, producing a narrow cleft of suitable size, shape, and nature to bind CoA. Sequence comparisons with homologous archaeal enzymes that naturally lack the N-terminal domain show that many amino acids lining this cleft are conserved. Besides the typical [4Fe-4S] center, the A-cluster contains only one proximal metal ion that, according to anomalous scattering data, is most likely Cu or Zn. Incorporation of a functional Ni(2)Fe(4)S(4) A-cluster would require only minor structural rearrangements. Using available structures, a plausible model of the interaction between CODH and the smaller ACS in archaeal multienzyme complexes is presented, along with a discussion of evolutionary relationships of the archaeal and bacterial enzymes.
author list (cited authors)
Volbeda, A., Darnault, C., Tan, X., Lindahl, P. A., & Fontecilla-Camps, J. C.
complete list of authors
Volbeda, Anne||Darnault, Claudine||Tan, Xiangshi||Lindahl, Paul A||Fontecilla-Camps, Juan C