MAPPING AND IDENTIFICATION OF THE MAJOR CELL WALL-ASSOCIATED COMPONENTS OF MYCOBACTERIUM-LEPRAE

Mycobacterium leprae, an obligate intracellular pathogen, can be deriv ed only from host tissue and thus affords the opportunity to study in vivo-expressed products responsible for the particular pathogenesis of leprosy. Despite considerable progress in the characterization of the proteins and secondary gene products of M. leprae, there is little in formation on the nature of the proteins associated with the cell envel ope. M. leprae has been fractionated into its major subcellular compon ents, cell wall, cytoplasmic membrane, and soluble cytosol. A number o f biochemical markers, including diaminopimelic acid content, monosacc haride composition, mycolic acid, and glycolipid distribution, were ap plied to their characterization, and two-dimensional gel electrophores is was used to map the component proteins. A total of 391 major protei ns spots were resolved, and 8 proteins were identified based on their reactivity to a panel of monoclonal antibodies and/or relative pi size . Microsequencing of six protein spots present in the cell wall fracti on allowed identification of new proteins, including the protein elong ation factor EF-Tu and a homolog for the Mycobacterium tuberculosis Mt rA response regulator. These results, together with previous studies, contribute to the progressive knowledge of the composition of the in v ivo-expressed proteins of M. leprae.