Analysis of the structure of mycolic acids of Mycobacterium simiae reveals a particular composition of α-mycolates in strain ‘habana’ TMC 5135, considered as immunogenic in tuberculosis and leprosy

摘要

Structural analysis of mycolic acids from Mycobacterium simiae (including some ‘habana’ strains) was carried out using 1H-NMR and MS. Results indicated that this species presents a general pattern of α-, α′- and keto-mycolates. α-Mycolates were composed of a complex mixture of 82 to 89 carbon atoms (C82–C89), with the predominant molecular species containing two di-substituted cyclopropane rings. Among keto-mycolates (C84–C89), those containing one trans di-substituted cyclopropane ring were the most abundant. The α′-mycolates were monounsaturated (C64, C66). According to MS and 1H-NMR data, the strains studied differed in fine structural details of α-mycolates and keto-mycolates. Notably, strain ‘habana’ TMC 5135 (belonging to the ‘habana’ group, and considered as highly immunogenic in tuberculosis and leprosy) presented a particular composition of α-mycolates, with a major component (C87) containing one cis plus one trans di-substituted cyclopropane ring, unlike the type strain of M. simiae and other strains of the ‘habana’ group (IPK-220 and IPK-337R), in which the major component (C84) contained two cis di-substituted cyclopropane rings. In spite of this finding, the ‘habana’ strains were closely related to each other and mainly differed from the type strain of M. simiae in some details of the fine structure of keto-mycolates. The present work indicated that within an identical general pattern of mycolic acids, there is a complex composition in M. simiae and structural variation among different strains, as reported for pathogenic species of the genus. Noteworthy was the particular composition of α-mycolates in strain ‘habana’ TMC 5135.