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Structural Basis of H-Dependent Conformational Change in a Bacterial MATE Transporter


Kusakizako TTsukasa , Claxton DPDerek P , Tanaka YYoshiki , Maturana ADAndrés D , Kuroda TTeruo , Ishitani RRyuichiro , Mchaourab HSHassane S , Nureki OOsamu . Structure (London, England : 1993). 2018 11 15; 27(2). 293-301.e3


Multidrug and toxic compound extrusion (MATE) transporters efflux toxic compounds using a Na or H gradient across the membrane. Although the structures of MATE transporters have been reported, the cation-coupled substrate transport mechanism remains controversial. Here we report crystal structures of VcmN, a Vibrio cholerae MATE transporter driven by the H gradient. High-resolution structures in two distinct conformations associated with different pHs revealed that the rearrangement of the hydrogen-bonding network around the conserved Asp35 induces the bending of transmembrane helix 1, as in the case of the H-coupled Pyrococcus furiosus MATE transporter. We also determined the crystal structure of the D35N mutant, which captured a unique conformation of TM1 facilitated by an altered hydrogen-bonding network. Based on the present results, we propose a common step in the transport cycle shared among prokaryotic H-coupled MATE transporters.