Linked Life Data

9342224

Source:http://linkedlifedata.com/resource/pubmed/id/9342224

Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
1997-11-24
pubmed:abstractText
Two missense mutants, A263P and S264P, and a deletion mutant des-Ala263, Ser264, have been constructed in the D1 protein of the cyanobacterium Synechocystis sp PCC 6803. All were expected to induce a significant conformational change in the QB-binding region of photosystem II (PSII). Although the des-Ala263, Ser264-D1 mutant accumulated some D1 protein in the thylakoid membrane it was unable to grow photoautotrophically or evolve oxygen. Thermoluminescence and chlorophyll fluorescence studies confirmed that this deletion mutant did not show any functional PSII activity. In contrast, [S264P]D1 was able to grow photoautotrophically and give light-saturated rates of oxygen evolution at 60% of the rate of the wild-type control strain, TC31. The A263P missense mutant was also able to evolve oxygen at 50% of TC31 rates although it did not readily grow photoautotrophically. Thermoluminescence, flash oxygen yield and chlorophyll fluorescence measurements indicated that in both missense mutants electron transfer from QA to QB was significantly impaired in dark adapted cells. However, QA to QB electron transfer could be photoactivated in the mutants by background illumination. Both the A263P and S264P mutants also showed an increase in resistance to the s-triazine family of herbicides although this feature did not hold for the phenolic herbicide, ioxynil. Of particular interest was that the two missense mutants, especially S264P, possessed a slower rate of turnover of the D1 protein compared with TC31 and in vivo contained detectable levels of a 41-kDa adduct consisting of D1 and the alpha subunit of cytochrome b559. When protein synthesis was blocked by the addition of lincomycin, D1 degradation was again slower in S264P than TC31. The results are discussed in terms of structural changes in the QB-binding region which affect herbicide and plastoquinone binding and perturb the normal regulatory factors that control the degradation of the D1 protein and its synchronisation with the synthesis of a replacement D1 protein.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
0014-2956
pubmed:author
pubmed:issnType
Print
pubmed:day
15
pubmed:volume
248
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
731-40
pubmed:dateRevised
2007-7-23
pubmed:meshHeading
pubmed-meshheading:9342224-Binding Sites, pubmed-meshheading:9342224-Cloning, Molecular, pubmed-meshheading:9342224-Cyanobacteria, pubmed-meshheading:9342224-Drug Resistance, pubmed-meshheading:9342224-Electron Transport, pubmed-meshheading:9342224-Electrophoresis, Polyacrylamide Gel, pubmed-meshheading:9342224-Escherichia coli, pubmed-meshheading:9342224-Fluorescence, pubmed-meshheading:9342224-Herbicides, pubmed-meshheading:9342224-Iodobenzenes, pubmed-meshheading:9342224-Light, pubmed-meshheading:9342224-Light-Harvesting Protein Complexes, pubmed-meshheading:9342224-Lincomycin, pubmed-meshheading:9342224-Luminescent Measurements, pubmed-meshheading:9342224-Membrane Proteins, pubmed-meshheading:9342224-Mutagenesis, Site-Directed, pubmed-meshheading:9342224-Nitriles, pubmed-meshheading:9342224-Oxygen, pubmed-meshheading:9342224-Photosynthesis, pubmed-meshheading:9342224-Photosynthetic Reaction Center Complex Proteins, pubmed-meshheading:9342224-Photosystem II Protein Complex, pubmed-meshheading:9342224-Temperature, pubmed-meshheading:9342224-Triazines
pubmed:year
1997
pubmed:articleTitle
Reduced turnover of the D1 polypeptide and photoactivation of electron transfer in novel herbicide resistant mutants of Synechocystis sp. PCC 6803.
pubmed:affiliation
Department of Biochemistry, Imperial College of Science, Technology and Medicine, London, UK.
pubmed:publicationType
Journal Article, Research Support, Non-U.S. Gov't