From ancestor to pathogen: Expansion and evolutionary adaptations of multidrug resistance causing MFS efflux pumps in mycobacteria.

Multidrug resistance (MDR) in Mycobacterium tuberculosis (Mtb) is a growing threat. Efflux pumps, particularly those belonging to the Major Facilitator Superfamily (MFS), play a key role in MDR. This study investigated MFS transporters across Mycobacterium spp. to understand their evolution and role in drug resistance. We conducted a proteome-wide analysis of MFS proteins in Mtb, Mycobacterium smegmatis (non-pathogenic), and Mycobacterium canettii (closely related ancestor of Mtb). Mtb, known for its MDR, possessed the highest abundance of MFS drug efflux pumps, while Mycobacterium smegmatis had the least. This suggests a link between MFS drug efflux pump abundance and MDR phenotypes. Interestingly, Mycobacterium canettii displayed an intermediate level, possibly indicating the presence of these pumps before the emergence of Mtb as a pathogen. Further analysis of Mtb proteome revealed 31 putative MFS transporters and 3 proteins from expanded MFS subfamilies. Phylogenetic analysis categorized them into thirteen distinct families based on structural features. These findings highlight the potential importance of MFS transporters in MDR and the pathogenicity of Mtb. Overall, this study highlights the evolutionary role of MFS transporters in bacterial adaptation to antibiotics. The observed correlation between efflux pump abundance and MDR suggests MFS transporters as promising targets for future anti-tuberculosis therapies. Further research on specific transporter functions within MFS subfamilies can pave the way for novel therapeutic strategies.