Sugar Binding and Protein Conformational Changes in Lactose Permease
نویسندگان
چکیده
منابع مشابه
Sugar binding and protein conformational changes in lactose permease.
Lactose permease is an integral membrane protein that uses the cell membrane's proton gradient for import of lactose. Based on extensive biochemical data and a substrate-bound crystal structure, intermediates involved in lactose/H(+) co-transport have been suggested. Yet, the transport mechanism, especially the coupling of protonation states of essential residues and protein conformational chan...
متن کاملThermodynamics of Nanobody Binding to Lactose Permease.
Camelid nanobodies (Nbs) raised against the outward-facing conformer of a double-Trp mutant of the lactose permease of Escherichia coli (LacY) stabilize the permease in outward-facing conformations. Isothermal titration calorimetry is applied herein to dissect the binding thermodynamics of two Nbs, one that markedly improves access to the sugar-binding site and another that dramatically increas...
متن کاملOpening the periplasmic cavity in lactose permease is the limiting step for sugar binding.
The lactose permease (LacY) catalyzes galactoside/H(+) symport via an alternating access mechanism in which sugar- and H(+)-binding sites in the middle of the molecule are alternatively exposed to either side of the membrane by opening and closing of inward- and outward-facing cavities. The crystal structures of wild-type LacY, as well as accessibility data for the protein in the membrane, prov...
متن کاملConformational flexibility at the substrate binding site in the lactose permease of Escherichia coli.
Glu-126 (helix IV) and Arg-144 (helix V) are charge paired and play a critical role in substrate binding in the lactose permease of Escherichia coli. When Glu-126 is replaced with Asp, the permease has relatively high activity, implying that helix V has sufficient flexibility to allow Arg-144 to accommodate the decreased length of the carboxylate-containing side chain of Asp-126. Helices IV and...
متن کاملSugar transport across lactose permease probed by steered molecular dynamics.
Escherichia coli lactose permease (LacY) transports sugar across the inner membrane of the bacterium using the proton motive force to accumulate sugar in the cytosol. We have probed lactose conduction across LacY using steered molecular dynamics, permitting us to follow molecular and energetic details of lactose interaction with the lumen of LacY during its permeation. Lactose induces a widenin...
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ژورنال
عنوان ژورنال: Biophysical Journal
سال: 2006
ISSN: 0006-3495
DOI: 10.1529/biophysj.106.085993