English
 
User Manual Privacy Policy Disclaimer Contact us
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT
 
 
DownloadE-Mail
  Combined computational and biochemical study reveals the importance of electrostatic interactions between the ‘‘pH sensor’’ and the cation binding site of the sodium/proton antiporter NhaA of Escherichia coli

Olkhova, E., Kozachkov, L., Padan, E., & Michel, H. (2009). Combined computational and biochemical study reveals the importance of electrostatic interactions between the ‘‘pH sensor’’ and the cation binding site of the sodium/proton antiporter NhaA of Escherichia coli. Proteins: Structure, Function, and Bioinformatics, 76(3), 548-559.

Item is

Basic

show hide
Item Permalink: http://hdl.handle.net/11858/00-001M-0000-0024-D7D0-2 Version Permalink: http://hdl.handle.net/11858/00-001M-0000-0024-D7D2-D
Genre: Journal Article

Files

show Files

Locators

show

Creators

show
hide
 Creators:
Olkhova, Elena1, Author              
Kozachkov, Lena, Author
Padan, Etana, Author
Michel, Hartmut1, Author              
Affiliations:
1Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Max Planck Society, ou_2068290              

Content

show
hide
Free keywords: NhaA Na+/H+ antiporter; conformation; single mutations; pH-dependent activation; continuum electrostatics
 Abstract: Sodium proton antiporters are essential enzymes that catalyze the exchange of sodium ions for protons across biological membranes. The crystal structure of NhaA has provided a basis to explore the mechanism of ion exchange and it's unique regulation by pH. Here, the mechanism of the pH activation of the antiporter is investigated through functional and computational studies of several variants with mutations in the ion-binding site (D163, D164). The most significant difference found computationally between the wild type antiporter and the active site variants, D163E and D164N, are low pKa values of Glu78 making them insensitive to pH. Although in the variant D163N the pKa of Glu78 is comparable to the physiological one, this variant cannot demonstrate the long-range electrostatic effect of Glu78 on the pH-dependent structural reorganization of trans-membrane helix X and, hence, is proposed to be inactive. In marked contrast, variant D164E remains sensitive to pH and can be activated by alkaline pH shift. Remarkably, as expected computationally and discovered here biochemically, D164E is viable and active in Na+/H+ exchange albeit with increased apparent KM. Our results unravel the unique electrostatic network of NhaA that connect the coupled clusters of the ‘‘pH sensor’’ with the binding site, which is crucial for pH activation of NhaA

Details

show
hide
Language(s): eng - English
 Dates: 2009
 Publication Status: Published in print
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Method: Peer
 Identifiers: eDoc: 473576
 Degree: -

Event

show

Legal Case

show

Project information

show

Source 1

show
hide
Title: Proteins: Structure, Function, and Bioinformatics
  Alternative Title : Proteins: Struct., Funct., Bioinf.
Source Genre: Journal
 Creator(s):
Affiliations:
Publ. Info: -
Pages: - Volume / Issue: 76 (3) Sequence Number: - Start / End Page: 548 - 559 Identifier: -