Structural diversity in the six-fold redundant set of acyl-CoA carboxyltransferases in Mycobacterium tuberculosis.

Mycobacterium tuberculosis contains multiple versions of the accA and accD genes that encode the alpha- and beta-subunits of at least three distinct multi-functional acyl-CoA carboxylase complexes. Because of its proposed involvement in pathogenic M. tuberculosis survival, the high-resolution crystal structure of the beta-subunit gene accD5 product has been determined and reveals a hexameric 356 kDa complex. Analysis of the active site properties of AccD5 and homology models of the other five M. tuberculosis AccD homologues reveals unexpected differences in their surface composition, providing a molecular rational key for a sorting mechanism governing correct acyl-CoA carboxylase holo complex assembly in M. tuberculosis.