Analysis of the a new group of acyl- CoA acyl-CoA carboxylases found in Streptomyces coelicolor A3(2).

DIACOVICH L., PEIRU S., KURTH D., PODESTA F., RODRIGUEZ E., AND GRAMAJO H.

Villa carlos Paz, Cordoba

Congreso; XXXVIII Reunion Anual de la Sociedad Argentina de Bioquimica y Biologia Molecular (SAIB); 2002

Sociedad Argentina de Bioquímica y Biología Molecular (SAIB).

Two acyl-CoA carboxylases from Streptomyces coelicolor have been successfully reconstituted from their purified components. Both complexes shared the same biotinylated alpha subunit, AccA2. The beta and the epsilon subunits were specific from each of the complexes; thus, for the PCC complex the beta and epsilon components are PccB and PccE, while for the ACC complex the components are AccB and AccE. The two complexes showed very low activity in the absence of the corresponding epsilon subunits, addition of PccE or AccE, dramatically increased the specific activity of the enzymes. The kinetic properties of the two acyl-CoA carboxylases showed a clear difference on their substrate specificity. The acetyl-CoA carboxylase (ACC) was able to carboxylate acetyl-, propionyl- or butyryl-CoA with approximately the same efficiency. The PCC could not recognize acetyl-CoA as a substrate, while the specificity constant for propionyl-CoA doubled that of the butyryl-CoA. For both enzymes the epsilon ƒnsubunits were found to specifically interact with their carboxyltransferase component forming a beta-epsilon subcomplex, this appears to facilitate the further interaction of these subunits with the alpha component.