Methylenomycin A resistance protein (also called MMR peptide) and similar multidrug resistance (MDR) transporters of the Major Facilitator Superfamily
This family is composed of bacterial, fungal, and archaeal multidrug resistance (MDR) transporters including several proteins from Bacilli such as methylenomycin A resistance protein (also called MMR peptide), tetracycline resistance protein (TetB), and lincomycin resistance protein LmrB, as well as fungal proteins such as vacuolar basic amino acid transporters, which are involved in the transport into vacuoles of the basic amino acids histidine, lysine, and arginine in Saccharomyces cerevisiae, and aminotriazole/azole resistance proteins. MDR transporters are drug/H+ antiporters (DHA) that mediate the efflux of a variety of drugs and toxic compounds, and confer resistance to these compounds. For example, MMR confers resistance to the epoxide antibiotic methylenomycin while TetB resistance to tetracycline by an active tetracycline efflux. MMR-like MDR transporters belong to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.
Feature 1:putative chemical substrate binding pocket [chemical binding site]
Evidence:
Comment:based on the structures of MFS transporters with bound substrates, substrate analogs, and/or inhibitors
Comment:since MFS proteins facilitate the transport of many different substrates including ions, sugar phosphates, drugs, neurotransmitters, nucleosides, amino acids, and peptides, the residues involved in substrate binding may not be strictly conserved among superfamily members
Comment:the substrate binding site or translocation pore has access to both sides of the membrane in an alternating fashion through a conformational change of the MFS transporter
Jiyao W et al.(2023). "The conserved domain database in 2023.",