Linked Life Data

17635927

Source:http://linkedlifedata.com/resource/pubmed/id/17635927

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
37
pubmed:dateCreated
2007-9-10
pubmed:abstractText
NhaA, the Na(+)/H(+) antiporter of Escherichia coli, exists in the native membrane as a homodimer of which two monomers have been suggested to be attached by a beta-hairpin at the periplasmic side of the membrane. Constructing a mutant deleted of the beta-hairpin, NhaA/Delta(Pro(45)-Asn(58)), revealed that in contrast to the dimeric mobility of native NhaA, the mutant has the mobility of a monomer in a blue native gel. Intermolecular cross-linking that monitors dimers showed that the mutant exists only as monomers in the native membrane, proteoliposomes, and when purified in beta-dodecyl maltoside micelles. Furthermore, pull-down experiments revealed that, whereas as expected for a dimer, hemagglutinin-tagged wild-type NhaA co-purified with His-tagged NhaA on a Ni(2+)-NTA affinity column, a similar version of the mutant did not. Remarkably, under routine stress conditions (0.1 m LiCl, pH 7 or 0.6 m NaCl, pH 8.3), the monomeric form of NhaA is fully functional. It conferred salt resistance to NhaA- and NhaB-deleted cells, and whether in isolated membrane vesicles or reconstituted into proteoliposomes exhibited Na(+)/H(+) antiporter activity and pH regulation very similar to wild-type dimers. Remarkably, under extreme stress conditions (0.1 m LiCl or 0.7 m NaCl at pH 8.5), the dimeric native NhaA was much more efficient than the monomeric mutant in conferring extreme stress resistance.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
14
pubmed:volume
282
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
26810-21
pubmed:meshHeading
pubmed:year
2007
pubmed:articleTitle
Monomers of the NhaA Na+/H+ antiporter of Escherichia coli are fully functional yet dimers are beneficial under extreme stress conditions at alkaline pH in the presence of Na+ or Li+.
pubmed:affiliation
Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, 91904 Jerusalem, Israel.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, Non-P.H.S., Research Support, Non-U.S. Gov't