MODULATION OF ACIL-COA CARBOXYLASE ACTIVITY IN MYCOBACTERIUM TUBERCULOSIS: CHARACTERIZATION OF MAF PROTEIN

DELFINA ENSINCK; DIACOVICH LAUTARO; ROLLAN LARA; GRAMAJO HUGO; GAGO GABRIELA

Modalidad Virtual

Congreso; LVII Annual Meeting of the Argentine Society for Biochemistry and Molecular Biology Research (SAIB) - XVI Annual Meeting of the Argentinean Society for General Microbiology (SAMIGE); 2021

SAIB - SAMIGE

Mycobacterium tuberculosis is the etiological agent of tuberculosis, an infectious disease with the highest cause of death in the world. Currently, it has been reestablished since the breach of extensive treatments with antibiotics, the continuous appearance of strains resistant to specific antimycobacterial drugs, and the HIV epidemic. In actinobacteria, a group of enzymes called acyl-CoA carboxylases complexes (ACCasa) catalyzes an essential step in the synthesis of fatty acids, the carboxylation of acetyl-CoA to produce the precursor malonyl-CoA. These enzymes can also carboxylate other substrates and have an important role in the synthesis of membrane lipids and cell wall. The cell walls of mycobacteria are unusually rich in lipids and have a huge variety of components that are essential for their viability, and the pathogenicity of these microorganisms. In M. tuberculosis and M. leprae the ACCasas enzymes produce malonyl-CoA, which is the precursor for the synthesis de novo of fatty acids and to produce meromycolic acids. Furthermore, these pathogens are capable to synthesize mycolic acids, mycocerosic acids, and methyl-branched fatty acids, for which they need other precursors such as methylmalonyl-CoA, formed by the carboxylation of propionyl-CoA. M. tuberculosis genomic analyses revealed that 3 genes encode the subunits α (accA1-3), and 6 genes encode the subunits β (accD1-6). Thus, M. tuberculosis might have 6 putative different ACCasa complexes. Mutagenesis studies postulate that the subunit α, AccA3, 3 subunits β, AccD4, AccD5 y AccD6, and the subunit ε, AccE5, might be essential for the viability of the microorganism. Even though some of these complexes are well characterized in many aspects, there is little information about their transcriptional and post-transcriptional regulation. The complex ACC5, formed by the proteins AccA3, AccD5, y AccE5, carboxylate preferentially propionyl-CoA instead of acetyl-CoA, suggesting that its physiological function is to generate methylmalonyl-CoA, as a precursor of methyl-brunched fatty acids. The characterization of a conditional mutant in the operon accD5-accE5 of M. smegmatis showed that the accD5 and accE5 genes are essential for bacteria growth. Protein Wag31 controls the septum formation and interacts with AccA3, a subunit shared with the ACCasas complexes. However, it is unknown if Wag31 has a regulatory role on AccA3. We have recently identified the Rv3282 gene of M. tuberculosis, which encodes for a protein called Maf. This gene is adjacent to accE5 gene, which encodes for the ε subunit from the complex ACC5. The function of Maf has not been studied, but its sequence has similarities with an inhibitor of septum formation. We hypothesize that the role of this protein might be involved in the interaction between Wag31 and AccA3. We have purified the protein Maf by its heterologous expression in E. coli and started its characterization in vitro.