INVESTIGADORES
DIACOVICH Lautaro
congresos y reuniones científicas
Título:
Rol of an essential acyl-CoA carboxylase in the primary and secondary metabolism of Strepromyces coelicolor.
Autor/es:
RODRIGUEZ E., BANCHIO C., DIACOVICH L., GRAMAJO H.
Lugar:
University of British Columbia. Vancouver, Canada. Ago 5-9, 2001.
Reunión:
Simposio; 12th International Symposium on the Biology of Actinomycetes.; 2001
Institución organizadora:
University of British Columbia.
Resumen:
Two genes, accB and accE, that form part of the same operon, were cloned from Streptomyces coelicolor A3(2). AccB is homologous to the carboxyl transferase domain of several propionyl- and acyl-CoA carboxylases of actinomycete origin, while AccE shows no significant homology to any known protein. Expression of accB and accE in Escherichia coli, and subsequent in vitro reconstitution of enzyme activity in the presence of the biotinylated proteins AccA1 or AccA2, confirmed that AccB was the carboxyl transferase subunit of an acyl-CoA carboxylase. The additional presence of AccE considerably enhanced the activity of the enzyme complex, suggesting that this small polypeptide is a functional component of the acyl-CoA carboxylase. The imposibilty of obtainining an accB null mutant and the thiostrepton-growth dependancy of a tipAp-accB conditional mutant, confirmed that AccB is essential for S. coelicolor viability. Normal growth phenotype in the absence of the inducer was restored in the conditional mutatn by the addition of exogenous long-chain fatty acids in the medium, indicating that the inducer-dependent phenotype was specifically related to a conditional block in fatty acid biosynthesis.Thus AccB, together with AccA2, which is also an essential protein, are the most likely components of an acyl-CoA carboxylase whose main physiological role is the synthesis of malonyl-CoA, the first committed step of fatty acid synthesis. Although normal growth of the conditional mutant was restored by fatty acids, the cultures did not produce actinorhodin or undecylprodigiosin; suggesting a direct participation of this enzyme complex in the supply of malonyl-CoA for the synthesis of these secondary metabolites.
