MabA (FabG1), a Mycobacterium tuberculosis protein involved in the long-chain fatty acid elongation system FAS-II

摘要: The fatty acid elongation system FAS-II is involved in the biosynthesis of mycolic acids, which are very long-chain acids cell envelope specific to Mycobacterium tuberculosis and other mycobacteria. A potential component FAS-II, protein MabA (FabG1), was overexpressed purified. Sedimentation equilibrium analyses revealed that undergoes a dimer tetramer self-association with dissociation constant 22 microM. detected by Western blotting mycobacterial cell-wall extract produces FPLC fraction. shown catalyse NADPH-specific reduction beta-ketoacyl derivatives, equivalent second step round. Unlike known homologous proteins, preferentially metabolizes substrates (C(8)-C(20)) has poor affinity for C(4) substrate, agreement specificities. Molecular modelling structure suggested presence an unusually hydrophobic substrate-binding pocket holding unique Trp residue, suitable fluorescence spectroscopic analyses. In enzyme kinetic data, spectral properties were different C(8)-C(16) ligands as compared ligand. Altogether, these data bring out distinctive enzymic structural MabA, correlate its predilection substrates, contrast most ketoacyl reductases.