Mycolic acid metabolic filiation and location in Mycobacterium aurum and Mycobacterium phlei.
Synchronous cultures of Mycobacterium aurum were used to prove a close relationship between cellular division and active synthesis of mycolic acids (characteristic long-chain 3-hydroxyacids, branched at position 2), confirming previous proposals. Mycolic acid biosynthesis was studied in two species (Mycobacterium phlei and M. aurum) each producing three types of mycolic acids: di-unsatured mycolates, oxomycolates and wax-ester mycolates (ester of dicarboxymycolic acid and 2-icosanol or 2-octadecanol). It was shown that unsaturated mycolates and oxomycolic acids were not directly related, whereas a metabolic filiation was confirmed between oxomycolate and wax ester mycolate: the latter derived from the former by a Baeyer-Villiger oxidation step, as has been proposed on the basis of structural considerations. By observing the labelling of the different mycolate pools in the cell, i.e. the organic-solvent-extractable fraction (essentially containing esters of trehalose and of glycerol) and the cell residue (assumed to be the cell-wall polymers), it was clear that oxomycolates and unsaturated mycolates appeared first in the extractable lipids, then in the wall-linked mycolates while wax-ester mycolates appeared first as wall-linked derivatives. Thus, it is proposed that mycolates could follow separate routes involving differently located enzymes to reach their complex forms either in extractable lipids or in the wall-linked arabino-galactan.
Lacave
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Centre de Recherche de Biochimie et Génétique Cellulaires, Université Paul Sabatier, Toulouse, France.
Laneelle
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Daffe
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Montrozier
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Laneelle
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D000085:Acetates / Q000378:metabolism; D019342:Acetic Acid; D002250:Carbon Radioisotopes; D007700:Kinetics; D009161:Mycobacterium / Q000254:growth & development / Q000378:metabolism*; D009168:Mycobacterium phlei / Q000378:metabolism*; D009171:Mycolic Acids / Q000302:isolation & purification / Q000378:metabolism*; D013045:Species Specificity
D000085:Acetates; D002250:Carbon Radioisotopes; D009171:Mycolic Acids; D019342:Acetic Acid