title: Crystal structure of a phosphorylation-coupled vitamin C transporter.
abstract: Bacteria use vitamin C (L-ascorbic acid) as a carbon source under anaerobic conditions. The phosphoenolpyruvate-dependent phosphotransferase system (PTS), comprising a transporter (UlaA), a IIB-like enzyme (UlaB) and a IIA-like enzyme (UlaC), is required for the anaerobic uptake of vitamin C and its phosphorylation to L-ascorbate 6-phosphate. Here, we present the crystal structures of vitamin C-bound UlaA from Escherichia coli in two conformations at 1.65-Å and 2.35-Å resolution. UlaA forms a homodimer and exhibits a new fold. Each UlaA protomer consists of 11 transmembrane segments arranged into a 'V-motif' domain and a 'core' domain. The V motifs form the interface between the two protomers, and the core-domain residues coordinate vitamin C. The alternating access of the substrate from the opposite side of the cell membrane may be achieved through rigid-body rotation of the core relative to the V motif.
authors: 1] State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China. [2] Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors: Ping
authors: P
authors: Luo
authors: 1] Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China. [2] Ministry of Education Key Laboratory of Protein Science, School of Life Sciences, Tsinghua University, Beijing, China.
authors: Xinzhe
authors: X
authors: Yu
authors: 1] State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China. [2] Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors: Weiguang
authors: W
authors: Wang
authors: Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors: Shilong
authors: S
authors: Fan
authors: Laboratory of Cell Biology, Rockefeller University, New York, New York, USA.
authors: Xiaochun
authors: X
authors: Li
authors: 1] State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing, China. [2] Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors: Jiawei
authors: J
authors: Wang
mesh_terms: D001205:Ascorbic Acid / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D001692:Biological Transport; D018360:Crystallography, X-Ray; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D026901:Membrane Transport Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D010766:Phosphorylation; D017434:Protein Structure, Tertiary
chemical_list: D029968:Escherichia coli Proteins; D026901:Membrane Transport Proteins; C473320:SgaT protein, E coli; D001205:Ascorbic Acid