Linked Life Data

14996834

Source:http://linkedlifedata.com/resource/pubmed/id/14996834

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
19
pubmed:dateCreated
2004-5-4
pubmed:abstractText
On the lumenal side of photosystem I (PSI), each of the two large core subunits, PsaA and PsaB, expose a conserved tryptophan residue to the surface. PsaB-Trp(627) is part of the hydrophobic recognition site that is essential for tight binding of the two electron donors plastocyanin and cytochrome c(6) to the donor side of PSI (Sommer, F., Drepper, F., and Hippler, M. (2002) J. Biol. Chem. 277, 6573-6581). To examine the function of PsaA-Trp(651) in binding and electron transfer of both donors to PSI, we generated the mutants PsaA-W651F and PsaA-W651S by site-directed mutagenesis and biolistic transformation of Chlamydomonas reinhardtii. The protein-protein interaction and the electron transfer between the donors and PSI isolated from the mutants were analyzed by flash absorption spectroscopy. The mutation PsaA-W651F completely abolished the formation of a first order electron transfer complex between plastocyanin (pc) and the altered PSI and increased the dissociation constant for binding of cytochrome (cyt) c(6) by more than a factor of 10 as compared with wild type. Mutation of PsaA-Trp(651) to Ser had an even larger impact on the dissociation constant. The K(D) value increased another 2-fold when the values obtained for the interaction and electron transfer between cyt c(6) and PSI from PsaA-W651S and PsaA-W651F are compared. In contrast, binding and electron transfer of pc to PSI from PsaA-W651S improved as compared with PSI from PsaA-W651F and admitted the formation of an inter-molecular electron transfer complex, resulting in a K(D) value of about 554 microm that is still five times higher than observed for wild type. These results demonstrate that PsaA-Trp(651) is, such as PsaB-Trp(627), crucial for high affinity binding of pc and cyt c(6) to PSI. Our results also indicate that the highly conserved structural recognition motif that is formed by PsaA-Trp(651) and PsaB-Trp(627) confers a differential selectivity in binding of both donors to PSI.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
May
pubmed:issn
0021-9258
pubmed:author
pubmed:issnType
Print
pubmed:day
7
pubmed:volume
279
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
20009-17
pubmed:dateRevised
2006-11-15
pubmed:meshHeading
pubmed-meshheading:14996834-Animals, pubmed-meshheading:14996834-Bacterial Proteins, pubmed-meshheading:14996834-Binding Sites, pubmed-meshheading:14996834-Chlamydomonas reinhardtii, pubmed-meshheading:14996834-Crystallography, X-Ray, pubmed-meshheading:14996834-Cytochromes c6, pubmed-meshheading:14996834-Electrons, pubmed-meshheading:14996834-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:14996834-Immunoblotting, pubmed-meshheading:14996834-Kinetics, pubmed-meshheading:14996834-Models, Molecular, pubmed-meshheading:14996834-Mutagenesis, Site-Directed, pubmed-meshheading:14996834-Mutation, pubmed-meshheading:14996834-Photosystem I Protein Complex, pubmed-meshheading:14996834-Plastocyanin, pubmed-meshheading:14996834-Protein Binding, pubmed-meshheading:14996834-Protein Conformation, pubmed-meshheading:14996834-Protein Structure, Secondary, pubmed-meshheading:14996834-Protein Structure, Tertiary, pubmed-meshheading:14996834-Spectrophotometry, pubmed-meshheading:14996834-Thylakoids
pubmed:year
2004
pubmed:articleTitle
The hydrophobic recognition site formed by residues PsaA-Trp651 and PsaB-Trp627 of photosystem I in Chlamydomonas reinhardtii confers distinct selectivity for binding of plastocyanin and cytochrome c6.
pubmed:affiliation
Lehrstuhl für Pflanzenphysiologie, Friedrich-Schiller-Universität Jena, Dornburgerstrasse 159, 07743 Jena, Germany.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't