The Two Carboxylases of Corynebacterium glutamicum Essential for Fatty Acid and Mycolic Acid Synthesis

Abstract

The suborder Corynebacterianeae comprises bacteria like Mycobacterium tuberculosis and Corynebacterium glutamicum, and these bacteria contain in addition to the linear fatty acids, unique ␣-branched ␤-hydroxy fatty acids, called mycolic acids. Whereas acetyl-coenzyme A (CoA) carboxylase activity is required to provide malonyl-CoA for fatty acid synthesis, a new type of carboxylase is apparently additionally present in these bacteria. It activates the ␣-carbon of a linear fatty acid by carboxylation, thus enabling its decarboxylative condensation with a second fatty acid to afford mycolic acid synthesis. We now show that the acetyl-CoA carboxylase of C. glutamicum consists of the biotinylated ␣-subunit AccBC, the ␤-subunit AccD1, and the small peptide AccE of 8.9 kDa, forming an active complex of approximately 812,000 Da. The carboxylase involved in mycolic acid synthesis is made up of the two highly similar ␤-subunits AccD2 and AccD3 and of AccBC and AccE, the latter two identical to the subunits of the acetyl-CoA carboxylase complex. Since AccD2 and AccD3 orthologues are present in all Corynebacterianeae, these polypeptides are vital for mycolic acid synthesis forming the unique hydrophobic outer layer of these bacteria, and we speculate that the two ␤-subunits present serve to lend specificity to this unique large multienzyme complex.

Substrate Specificity of the 3-Methylcrotonyl Coenzyme A (CoA) and Geranyl-CoA Carboxylases from Pseudomonas aeruginosa

“…2). A similar behavior was observed during the expression of the AccD1-His subunit of acetyl-CoA carboxylase from Corynebacterium glutamicum (12) and the acyl-CoA carboxylase from Streptomyces coelicolor A3 (2) (5).…”

“…The kinetic constants of this enzyme for MC-CoA were a K 0.5 of 9.8 M and a V max of 279 nmol/ min ⅐ mg of protein; these values are in agreement with values obtained with the MCCase purified from of the native host, P. aeruginosa. The catalytic efficiencies (V max /K m ) of the two enzyme preparations also were similar (46 and 56, respectively), indicating that the recombinant proteins and the heterologous expression did not affect MCCase functionality, as occurs in other carboxylases (5,12). On the other hand, the kinetic dependence on the ATP and NaHCO 3 substrates showed a sigmoidal response, suggesting an allosteric regulation of MCCase by ATP and NaHCO 3 ( Fig.…”

Efficient Synthesis of Eriodictyol from l -Tyrosine in Escherichia coli

“…Because a low level of intracellular malonyl-CoA is a major limitation for flavonoid biosynthesis in E. coli, several strategies were applied to enhance the availability of malonyl-CoA (25,26). By employing these strategies, the final eriodictyol production was obtained directly from L-tyrosine instead of the expensive substrate caffeic (29,30). The accBC gene was amplified with primers accBC-F (containing an EcoRV site) and accBC-R (containing a KpnI site) ( Table 2).…”

Deletion of manC in Corynebacterium glutamicum results in a phospho-myo-inositol mannoside- and lipoglycan-deficient mutant

“…Consequently, a comprehensive analysis of the role of these enzymes in cell wall biogenesis has always been limited. In such a scenario, the use of the easily cultivable and non-pathogenic C. glutamicum has been very useful, especially in terms of otherwise essential genes in mycobacteria, involved in the biosynthesis of mycolic acids (Gande et al, 2004(Gande et al, , 2007, arabinogalactan (Alderwick et al, 2006a(Alderwick et al, , b, 2007Birch et al, 2008;Seidel et al, 2007) and LAM (Gibson et al, 2003;Mishra et al, 2007Mishra et al, , 2008aMishra et al, , b, 2009Mishra et al, , 2011aTatituri et al, 2007a, b).…”