Structural Basis Of The Human Glucose Transporter Reveals The Transport Mechanism

Glucose is one of the most essential carbon source for creatures,which can be widely used from prokaryotes to eukaryotes,from unicellular to multicellular organisms.As the substrate of respiration and other biochemical reactions in cells like glycosylation,glucose is undoubtedly important small molecule for life beings.However,it can not freely diffuse across the lipid bilayer because of the strong hydrophilicity,so that the uptake and utilize of glucose in cell need facilitating by membrane transport.Therefore,the exploration of glucose transport is significant for studying its metabolism and regulation.Most mammalian cells uptake glucose by glucose transporters,which belong to the sugar porter family in major facilitator superfamily(MFS).So far,the study of GLUTs has been transit to cell biology and biochemistry level,and their function,properties and effects on various diseases have been preliminarily elucidated.Nevertheless,the molecular mechanism of glucose transport by GLUTs remains elusive.So the structural and functional investigations of GLUTs in molecular level make a big difference and have essential biological meanings.In this thesis,we successfully got well behaved human GLUT1 protein by recombinant expression and solved the 3.2 ? crystal structure at first.After structural analysis,we build a primary transport model for GLUTs and describe the hydrogen bond network in intra-and extra-celluar gates.Also,dysfunctional mutations were mapped in the structure to illustrate the possible nosogenesis.Then we got substrate-bound,outward-facing and competitive inhibitor-bound,outward-facing/open structures of GLUT3 by LCP.It makes that possible to complete the important conformations in a transport cycle.Combined with the analysis of isotope assays,substrate recognition and transport mechanism are illustrated.As a brief summary,we solved important structures of human GLUTs and set up the isotope assay.And we firstly described the detailed transport model and interpreted the transport mechanism of GLUTs at molecular level with structural analysis and biochemical experiments,providing structural basis for structure-based drug design.