Structure of the YajR transporter suggests a transport mechanism based on the conserved motif A.
The major facilitator superfamily (MFS) is the largest family of secondary active transporters and is present in all life kingdoms. Detailed structural basis of the substrate transport and energy-coupling mechanisms of these proteins remain to be elucidated. YajR is a putative proton-driven MFS transporter found in many Gram-negative bacteria. Here we report the crystal structure of Escherichia coli YajR at 3.15 Å resolution in an outward-facing conformation. In addition to having the 12 canonical transmembrane helices, the YajR structure includes a unique 65-residue C-terminal domain which is independently stable. The structure is unique in illustrating the functional role of "sequence motif A." This highly conserved element is seen to stabilize the outward conformation of YajR and suggests a general mechanism for the conformational change between the inward and outward states of the MFS transporters.
National Laboratory of Macromolecules, National Center of Protein Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Daohua
D
Jiang
Yan
Y
Zhao
Xianping
X
Wang
Junping
J
Fan
Jie
J
Heng
Xuehui
X
Liu
Wei
W
Feng
Xusheng
X
Kang
Bo
B
Huang
Jianfeng
J
Liu
Xuejun Cai
XC
Zhang
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D001692:Biological Transport; D018360:Crystallography, X-Ray; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid
D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C584948:YajR protein, E coli
charge relay; charge-dipole interaction; membrane potential; protonation