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Effect of Detergents on Galactoside Binding by Melibiose Permeases

Title
Effect of Detergents on Galactoside Binding by Melibiose Permeases
Author
채필석
Keywords
RESONANCE ENERGY-TRANSFER; SEROVAR TYPHIMURIUM MELB; ESCHERICHIA-COLI; LACTOSE PERMEASE; TRANSPORT PROTEINS; MEMBRANE-VESICLES; NA+; STABILIZATION; AMPHIPHILES; MECHANISM
Issue Date
2015-10
Publisher
AMER CHEMICAL SOC
Citation
BIOCHEMISTRY, v. 54, NO 38, Page. 5849-5855
Abstract
The effect of various detergents on the stability and function of the melibiose permeases of Escherichia coli (MelB(Ec)) and Salmonella typhimurium (MelB(st)) was studied. In n-dodecyl-beta-D-maltoside (DDM) or n-undecyl-beta-Dmaltoside (UDM), WT MelBst binds melibiose with an affinity similar to that in the membrane. However, with WT MelB(Ec), or MelB(st) mutants (Arg141 -˃ Cys, Arg295 -˃ Cys, or Arg363 -˃ Cys), galactoside binding is not detected in these detergents, but binding to the phosphotransferase protein IIA(Glc) is maintained. In the amphiphiles lauryl maltose neopentyl glycol (MNG-3) or glyco-diosgenin (GDN), galactoside binding with all of the MelB proteins is observed, with slightly reduced affinities. MelB(st) is more therrnostable than MelB(Ec) and the thermostability of either MelB is largely increased in MNG-3 or GDN. Therefore, the functional defect with DDM or UDM likely results from the relative instability of the sensitive MelB proteins, and stability, as well as galactoside binding, is retained in MNG-3 or GDN. Furthermore, isothermal titration calorirnetry of melibiose binding with MelB(st) shows that the favorable entropic contribution to the binding free energy is decreased in MNG-3, indicating that the conformational dynamics of MelB is restricted in this detergent.
URI
http://pubs.acs.org/doi/10.1021/acs.biochem.5b00660http://hdl.handle.net/20.500.11754/28097
ISSN
0006-2960
DOI
10.1021/acs.biochem.5b00660
Appears in Collections:
GRADUATE SCHOOL[S](대학원) > BIONANOTECHNOLOGY(바이오나노학과) > Articles
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