2KBV

Structural and functional analysis of TM XI of the NHE1 isoform of thE NA+/H+ exchanger

Summary for 2KBV

• Entry DOI: 10.2210/pdb2kbv/pdb
• NMR Information: BMRB: 16056
• Descriptor: Sodium/hydrogen exchanger 1 (1 entity in total)
• Functional Keywords: transmembrane, nhe1, micelle, alternative splicing, antiport, glycoprotein, ion transport, membrane, phosphoprotein, sodium, sodium transport, transport, membrane protein
• Biological source: Homo sapiens
• Total number of polymer chains: 1
• Total formula weight: 2886.42

Authors

Lee, B.L.,Li, X.,Liu, Y.,Sykes, B.D.,Fliegel, L. (deposition date: 2008-12-09, release date: 2009-01-27, Last modification date: 2023-06-14)

Primary citation

Lee, B.L.,Li, X.,Liu, Y.,Sykes, B.D.,Fliegel, L.
Structural and Functional Analysis of Transmembrane XI of the NHE1 Isoform of the Na+/H+ Exchanger
J.Biol.Chem., 284:11546-11556, 2009

PubMed Abstract: The Na(+)/H(+) exchanger isoform 1 is a ubiquitously expressed integral membrane protein that regulates intracellular pH in mammals by extruding an intracellular H(+) in exchange for one extracellular Na(+). We characterized structural and functional aspects of the critical transmembrane (TM) segment XI (residues 449-470) by using cysteine scanning mutagenesis and high resolution NMR. Each residue of TM XI was mutated to cysteine in the background of the cysteine-less protein and the sensitivity to water-soluble sulfhydryl reactive compounds MTSET ((2-(trimethylammonium) ethyl)methanethiosulfonate) and MTSES ((2-sulfonatoethyl) methanethiosulfonate) was determined for those residues with at least moderate activity remaining. Of the residues tested, only proteins with mutations L457C, I461C, and L465C were inhibited by MTSET. The activity of the L465C mutant was almost completely eliminated, whereas that of the L457C and I461C mutants was partially affected. The structure of a peptide representing TM XI (residues Lys(447)-Lys(472)) was determined using high resolution NMR spectroscopy in dodecylphosphocholine micelles. The structure consisted of helical regions between Asp(447)-Tyr(454) and Phe(460)-Lys(471) at the N and C termini of the peptide, respectively, connected by a region with poorly defined, irregular structure consisting of residues Gly(455)-Gly(459). TM XI of NHE1 had a structural similarity to TM XI of the Escherichia coli Na(+)/H(+) exchanger NhaA. The results suggest that TM XI is a discontinuous helix, with residue Leu(465) contributing to the pore.

PubMed: 19176522
DOI: 10.1074/jbc.M809201200

Experimental method

SOLUTION NMR