Mycobacterium smegmatis MSMEG_3705 Encodes a Selective Major Facilitator Superfamily Efflux Pump with Multiple Roles

Mycobacterium smegmatis mc2155 MSMEG_3705 gene was annotated to encode a transporter protein that contains 12 alpha-helical transmembrane domains. We predicted MSMEG_3705 encoding a major facilitator superfamily (MFS) member. To confirm the prediction, the M. smegmatis mc2155 MSMEG_3705 gene was deleted. The MSMEG_3705 deletion mutant strain M. smegmatis mc2155 ∆MSMEG_3705 was more sensitive to capreomycin. Moreover, M. smegmatis mc2155 ∆MSMEG_3705 strain accumulated more ethidium bromide intracellular than wild-type M. smegmatis mc2155. Quite unexpectedly, M. smegmatis mc2155 ∆MSMEG_3705 grew faster than the wild-type M. smegmatis mc2155. The upregulation of the expression of MSMEG_3706, a gene encoding isocitrate lyase downstream MSMEG_3705, in the deletion mutant, might underlie such faster growth in the mutant. The study showed that MSMEG_3705 encodes a genuine MFS member and plays significant role in bacterial growth and antibiotics resistance.