Investigation of sugar binding kinetics of the E. coli sugar/H+ symporter XylE using solid-supported membrane-based electrophysiology
| العنوان: | Investigation of sugar binding kinetics of the E. coli sugar/H+ symporter XylE using solid-supported membrane-based electrophysiology |
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| المؤلفون: | Andre Bazzone, Laura Tesmer, Derya Kurt, H. Ronald Kaback, Klaus Fendler, M. Gregor Madej |
| المصدر: | The Journal of Biological Chemistry |
| بيانات النشر: | American Society for Biochemistry and Molecular Biology, 2021. |
| سنة النشر: | 2021 |
| مصطلحات موضوعية: | Monosaccharide Transport Proteins, membrane transport, bioenergetics, DDM, n-dodecyl-beta-d-maltoside, Biochemistry, FucP, fucose permease, MFS, EHS, high-energy occluded intermediate (substrate-bound and protonated), Escherichia coli, Molecular Biology, LPR, lipid-to-protein ratio, SSM, LacY, lactose permease, energy coupling, Symporters, Escherichia coli Proteins, XylE, Escherichia coli xylose permease, MFS, major facilitator superfamily, Membrane Transport Proteins, Cell Biology, sugar transporter, Electrophysiology, TDG, β-d-galactopyranosyl-1-thio-β-d-galactopyranoside, Kinetics, Glucose, BC, betweenness centrality, XylE, Carbohydrate Metabolism, SSM, solid-supported membrane, Sugars, induced fit, Research Article, PSS, pre steady-state |
| الوصف: | Bacterial transporters are difficult to study using conventional electrophysiology because of their low transport rates and the small size of bacterial cells. Here, we applied solid-supported membrane–based electrophysiology to derive kinetic parameters of sugar translocation by the Escherichia coli xylose permease (XylE), including functionally relevant mutants. Many aspects of the fucose permease (FucP) and lactose permease (LacY) have also been investigated, which allow for more comprehensive conclusions regarding the mechanism of sugar translocation by transporters of the major facilitator superfamily. In all three of these symporters, we observed sugar binding and transport in real time to determine KM, Vmax, KD, and kobs values for different sugar substrates. KD and kobs values were attainable because of a conserved sugar-induced electrogenic conformational transition within these transporters. We also analyzed interactions between the residues in the available X-ray sugar/H+ symporter structures obtained with different bound sugars. We found that different sugars induce different conformational states, possibly correlating with different charge displacements in the electrophysiological assay upon sugar binding. Finally, we found that mutations in XylE altered the kinetics of glucose binding and transport, as Q175 and L297 are necessary for uncoupling H+ and d-glucose translocation. Based on the rates for the electrogenic conformational transition upon sugar binding (>300 s−1) and for sugar translocation (2 s−1 − 30 s−1 for different substrates), we propose a multiple-step mechanism and postulate an energy profile for sugar translocation. We also suggest a mechanism by which d-glucose can act as an inhibitor for XylE. |
| اللغة: | English |
| تدمد: | 1083-351X 0021-9258 |
| الوصول الحر: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::173ab5f163d13e9c80e23eacd2a83eefTest http://europepmc.org/articles/PMC8784342Test |
| حقوق: | OPEN |
| رقم الانضمام: | edsair.doi.dedup.....173ab5f163d13e9c80e23eacd2a83eef |
| قاعدة البيانات: | OpenAIRE |
| تدمد: | 1083351X 00219258 |
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