Functional Study On The C-terminus Of EmbC Protein From Mycobacterium Smegmatis

Mycobacterium tuberculosis, the causative agent of tuberculosis (TB), has infected the human being for thousands years. In recent years, the impressive emergence and wide distribution of multidrug-resistant (MDR) strains of M. tuberculosis has a significant impact for the increased incidence of TB. M. tuberculosis is an extraordinarily successful pathogen with the remarkable ability to persist and replicate within the normally hostile environment of macrophages. An important key to the success of pathogenic M. tuberculosis is likely to be its unusual cell wall structure and its interactions with the immune system.D-Arabinans, composed of D-arabinofuranose (D-Araf), dominate the structure of mycobacterial cell walls in two settings, as part of lipoarabinomannan (LAM) and arabinogalactan, each with markedly different structures and functions. The arabinan in AG and LAM has the same reducing α-(1→5) arabinosyl chain, but different terminal motif. The nonreducing end of the arabinan in AG is terminated by branched Ara₆,[β -D-Araf-(1→2)-α-D-Araf-(1→)]₂→(3,5)-α-D-Araf-(1→5)-α-D-Araf, while the nonreducing end of the arabinan in LAM is terminated by both Ara₆, the same as in AG, and linear Ara₄, β -D-Araf-(1→2)-α-D-Araf-(1→5)-α-D-Araf-(1→5)-α-D-Araf. Mycolic acid arabinogalactan - peptidoglycan (mAGP) composed of the backbone of the mycobacterial cell wall. LAM consists of arabinan, mannan and phosphatidyl -myo- inositol anchor, and the arabinan and mannan are non-covalently attached to the plasma membrane through the phosphatidyl-myo-inositol anchor. The arabinan is extend to the exterior of the cell wall backbone, and the non-reducing ends of the arabinan are capped with mannose residues responsible for much of their biological roles relating to host pathogen interaction.Little is known about the synthesis of the arabinan in AG and LAM. EmbA,...