Linked Life Data

2104838

Source:http://linkedlifedata.com/resource/pubmed/id/2104838

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1990-2-21
pubmed:abstractText
Pharaonis halorhodopsin is a light-driven transport system for chloride, similarly to the previously described halorhodopsin, but we find that it transports nitrate as effectively as chloride. We studied the photoreactions of the purified, detergent-solubilized pharaonis pigment with a gated multichannel analyzer. At a physiological salt concentration (4 M NaCl), the absorption spectra and rate constants of rise and decay for intermediates of the photocycle were similar to those for halorhodopsin. In buffer containing nitrate, halorhodopsin exhibits a second, truncated photocycle; this difference in the photoreaction of the pigment occurs when an anion is bound in such a way as to preclude transport. As expected from the lack of anion specificity in the transport, the photocycle of pharaonis halorhodopsin was nearly unaffected by replacement of chloride with nitrate. All presumed buried positively charged residues, which might play a role in anion binding, are conserved in the two pigments. At the extracellular end of the presumed helix C, however, an arginine residue is found in halorhodopsin, but not in pharaonis halorhodopsin, and an arginine-rich segment between the presumed helices A and B in halorhodopsin is replaced by a less positively charged sequence in pharaonis halorhodopsin (Lanyi, J. K., Duschl, A., Hatfield, G. W., May, K., and Oesterhelt, D. (1990) J. Biol. Chem. 265, 1253-1260). One or both of these alterations may explain the difference in the anion selectivity of the two proteins.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Jan
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
25
pubmed:volume
265
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
1261-7
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1990
pubmed:articleTitle
Properties and photochemistry of a halorhodopsin from the haloalkalophile, Natronobacterium pharaonis.
pubmed:affiliation
Department of Physiology and Biophysics, University of California, Irvine 92717.
pubmed:publicationType
Journal Article, Research Support, U.S. Gov't, P.H.S., Research Support, U.S. Gov't, Non-P.H.S.