title: Cyclopropanation of α-mycolic acids is not required for cording in Mycobacterium brumae and Mycobacterium fallax.
abstract: The capacity to form microscopic cords (cording) of Mycobacterium species has been related to their virulence. The compounds responsible for cording are unknown, but a recent study has shown that cording could be related to the fine structure of α-mycolic acids. This investigation attributes the need for a proximal cyclopropane in α-mycolic acids for cording in Mycobacterium tuberculosis and Mycobacterium bovis BCG and proposes cyclopropanases as good targets for new chemotherapeutic agents. As other Mycobacterium species in addition to M. tuberculosis and M. bovis form microscopic cords, it would be of major interest to know whether the relationship between proximal cyclopropanation of α-mycolic acids and cording could be extended to non-tuberculous mycobacteria. In this study, we have examined the correlation between the cording and cyclopropanation of α-mycolic acids in two species, Mycobacterium brumae and Mycobacterium fallax. Scanning electron microscopy images showed, for the first time to our knowledge, the fine structure of microscopic cords of M. brumae and M. fallax, confirming that these two species form true cords. Furthermore, NMR analysis performed on the same cording cultures corroborates the absence of cyclopropane rings in their α-mycolic acids. Therefore, we can conclude that the correlation between cording and cyclopropanation of α-mycolic acids cannot be extended to all mycobacteria. As M. brumae and M. fallax grow rapidly and have a simple pattern of mycolic acids (only α-unsaturated mycolic acids), we propose these two species as suitable models for the study of the role of mycolic acids in cording.
authors.affiliation: Departament de Genètica i de Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Brambilla
authors.affiliation: Servei de Microscòpia Electrònica, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Sánchez-Chardi
authors.affiliation: Servei de Ressonància Magnètica Nuclear, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain.
authors.forename: Míriam
authors.initials: M
authors.lastname: Pérez-Trujillo
authors.affiliation: Departament de Genètica i de Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain.
authors.forename: Esther
authors.initials: E
authors.lastname: Julián
authors.affiliation: Departament de Genètica i de Microbiologia, Facultat de Biociències, Universitat Autònoma de Barcelona, 08193 Barcelona, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Luquin
mesh_terms: D003521:Cyclopropanes / Q000737:chemistry / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009161:Mycobacterium / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*; D009171:Mycolic Acids / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D003521:Cyclopropanes; D009171:Mycolic Acids; C030797:cyclopropane