Linked Life Data

8639619

Source:http://linkedlifedata.com/resource/pubmed/id/8639619

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
21
pubmed:dateCreated
1996-7-17
pubmed:abstractText
Both sensory rhodopsin I, a phototaxis receptor, and bacteriorhodopsin, a light-driven proton pump, have homologous residues which have been identified as critical for bacteriorhodopsin functioning. This includes Asp76, which in the case of bacteriorhodopsin (Asp85) functions as both the Schiff base counterion and the proton acceptor. Sensory rhodopsin I exists in a pH dependent equilibrium between two different forms in the absence of its transducer protein HtrI. At pH below 7, it exists primarily in a blue form (lambda max = 587 nm) which functions as a phototaxis signal transducer when complexed to HtrI, while at higher pH, it converts to a purple proton-transporting form similar to bacteriorhodopsin (lambda max = 550 nm). We report ATR-FTIR difference spectra obtained from both low- and high-pH forms of purified sensory rhodopsin I reconstituted into lipid vesicles. The low-pH species has an ethylenic C = C stretch mode at 1520 cm-1 which shifts to 1526 cm-1 in the high-pH form. No frequency shift was found for the mutant D76N, in agreement with visible absorption measurements. Weak negative/positive bands at 1763/1751 cm-1 previously assigned to a perturbation of the C = O stretch mode of Asp76 during S373 formation in the low-pH form are replaced by a single intense positive band near 1749 cm-1 in the high-pH form. These results along with the effects of H/D exchange show that Asp76 is protonated in the signal-transducing form of sensory rhodopsin I and is ionized and functions as the counterion and Schiff base proton acceptor in the proton-transporting high-pH form of sensory rhodopsin I similar to bacteriorhodopsin.
pubmed:grant
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0006-2960
pubmed:author
pubmed:issnType
Print
pubmed:day
28
pubmed:volume
35
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
6690-6
pubmed:dateRevised
2008-11-21
pubmed:meshHeading
pubmed:year
1996
pubmed:articleTitle
Asp76 is the Schiff base counterion and proton acceptor in the proton-translocating form of sensory rhodopsin I.
pubmed:affiliation
Department of Physics, Boston University, Boston, Massachusetts 02215, USA.
pubmed:publicationType
Journal Article, Comparative Study, Research Support, U.S. Gov't, P.H.S.