Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
School of Life Sciences & Department of Chemistry, The University of Warwick, Coventry, CV4 7AL, UK.
Nat Commun. 2019 Oct 11;10(1):4657. doi: 10.1038/s41467-019-12673-w.
Nucleotide sugars are the activated form of monosaccharides used by glycosyltransferases during glycosylation. In eukaryotes the SLC35 family of solute carriers are responsible for their selective uptake into the Endoplasmic Reticulum or Golgi apparatus. The structure of the yeast GDP-mannose transporter, Vrg4, revealed a requirement for short chain lipids and a marked difference in transport rate between the nucleotide sugar and nucleoside monophosphate, suggesting a complex network of regulatory elements control transport into these organelles. Here we report the crystal structure of the GMP bound complex of Vrg4, revealing the molecular basis for GMP recognition and transport. Molecular dynamics, combined with biochemical analysis, reveal a lipid mediated dimer interface and mechanism for coordinating structural rearrangements during transport. Together these results provide further insight into how SLC35 family transporters function within the secretory pathway and sheds light onto the role that membrane lipids play in regulating transport across the membrane.
核苷酸糖是糖基转移酶在糖基化过程中使用的单糖的活性形式。在真核生物中，溶质载体家族 SLC35 负责将其选择性摄取到内质网或高尔基体中。酵母 GDP-甘露糖转运蛋白 Vrg4 的结构揭示了短链脂质的需求以及核苷酸糖和核苷单磷酸之间运输速率的显著差异，这表明调控元件的复杂网络控制着这些细胞器的运输。在这里，我们报告了 Vrg4 与 GMP 结合的复合物的晶体结构，揭示了 GMP 识别和运输的分子基础。分子动力学与生化分析相结合，揭示了脂介导的二聚体界面和运输过程中结构重排的协调机制。这些结果进一步深入了解 SLC35 家族转运蛋白在分泌途径中的作用，并揭示了膜脂在调节跨膜运输中的作用。
