title: The influence of AccD5 on AccD6 carboxyltransferase essentiality in pathogenic and non-pathogenic Mycobacterium.
abstract: Malonyl-coenzyme A (CoA) is a crucial extender unit for the synthesis of mycolic and other fatty acids in mycobacteria, generated in a reaction catalyzed by acetyl-CoA carboxylase. We previously reported on the essentiality of accD6Mtbencoding the functional acetyl-CoA carboxylase subunit in Mycobacterium tuberculosis. Strikingly, the homologous gene in the fast-growing, non-pathogenic Mycobacterium smegmatis - (accD6Msm) appeared to be dispensable, and its deletion did not influence the cell lipid content. Herein, we demonstrate that, despite the difference in essentiality, accD6Msmand accD6Mtbencode proteins of convergent catalytic activity in vivo. To identify an alternative, AccD6-independent, malonyl-CoA synthesis pathway in M. smegmatis, a complex genetic approach combined with lipid analysis was applied to screen all five remaining carboxyltransferase genes (accD1-accD5) with respect to their involvement in mycolic acid biosynthesis and ability to utilize acetyl-CoA as the substrate for carboxylation. This approach revealed that AccD1Msm, AccD2Msmand AccD3Msmare not essential for mycolic acid biosynthesis. Furthermore, we confirmed in vivo the function of AccD4Msmas an essential, long-chain acyl-CoA carboxyltransferase, unable to carboxylate short-chain substrate. Finally, our comparative studies unambiguously demonstrated between-species difference in in vivo ability of AccD5 carboxyltransferase to utilize acetyl-CoA that influences AccD6 essentiality in pathogenic and non-pathogenic mycobacteria.
authors.affiliation: Institute for Medical Biology, Polish Academy of Sciences, Lodz, Poland.
authors.forename: Jakub
authors.initials: J
authors.lastname: Pawelczyk
authors.affiliation: Centre National de la Recherche Scientifique FRE 3689, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé, Université de Montpellier, Montpellier, France.
authors.forename: Albertus
authors.initials: A
authors.lastname: Viljoen
authors.affiliation: Centre National de la Recherche Scientifique FRE 3689, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé, Université de Montpellier, Montpellier, France.|INSERM, CPBS, 34293 Montpellier, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Kremer
authors.affiliation: Institute for Medical Biology, Polish Academy of Sciences, Lodz, Poland.
authors.forename: Jaroslaw
authors.initials: J
authors.lastname: Dziadek
mesh_terms: D053898:Biosynthetic Pathways; D019878:Carboxyl and Carbamoyl Transferases / Q000235:genetics* / Q000378:metabolism*; D004789:Enzyme Activation; D005227:Fatty Acids / Q000378:metabolism; D050296:Microbial Viability / Q000235:genetics; D009154:Mutation; D009161:Mycobacterium / Q000201:enzymology* / Q000235:genetics*; D020102:Mycobacterium smegmatis / Q000235:genetics / Q000378:metabolism; D009169:Mycobacterium tuberculosis / Q000235:genetics / Q000378:metabolism; D009171:Mycolic Acids / Q000378:metabolism; D010641:Phenotype; D013379:Substrate Specificity; D014774:Virulence
chemical_list: D005227:Fatty Acids; D009171:Mycolic Acids; D019878:Carboxyl and Carbamoyl Transferases