Molecular and biophysical analysis of herbicide-resistant mutants of Chlamydomonas reinhardtii: Structure-function relationship of the photosystem II D1 polypeptide

• Published in: The Plant cell Vol. 1; no. 3; pp. 361 - 371
• Main Authors: Erickson, J.M. (University of California, Los Angeles, CA), Pfister, K, Rahire, M, Togasaki, R.K, Mets, L, Rochaix, J.D
• Format: Journal Article
• Language: English
• Published: United States American Society of Plant Physiologists 01.03.1989
• Subjects: Amino Acid Sequence; AMINO ACID SEQUENCES; Animals; ATRAZINA; ATRAZINE; Base Sequence; BINDING SITE; Binding Sites; BROMACIL; BROMACILO; CHEMICAL RESISTANCE; Chlamydomonas reinhardtii - drug effects; Chlamydomonas reinhardtii - genetics; CHLOROPHYCEAE; CHLOROPHYLLE; CHLOROPHYLLS; Chloroplasts; Cloning, Molecular; CLOROFILAS; DIURON; DNA; Drug Resistance - genetics; ELECTRON TRANSFER; Fluorescence; FLUORESCENCE DECAY; Fluorometry; FOTOSINTESIS; GENE; GENES; Genetic mutation; HERBICIDAS; HERBICIDE; Herbicide resistance; HERBICIDES; Herbicides - pharmacology; Kinetics; MOLECULAR SEQUENCE DATA; MUTANT; MUTANTES; MUTANTS; Mutation; NUCLEOTIDE; NUCLEOTIDES; NUCLEOTIDOS; OPTICAL PROPERTIES; OXIDOREDUCTIONS; OXIRREDUCION; OXYDOREDUCTION; PEPTIDE; PEPTIDES; PEPTIDOS; PHOTOSYNTHESE; PHOTOSYNTHESIS; Photosynthetic Reaction Center Complex Proteins - chemistry; Photosynthetic Reaction Center Complex Proteins - genetics; Photosystem II; Photosystem II Protein Complex; Plant cells; Plants; PROPIEDADES OPTICAS; PROPRIETE OPTIQUE; Protein Conformation; PSBA GENE; RESISTANCE AUX PRODUITS CHIMIQUES; RESISTENCIA QUIMICA; Restriction Mapping; Structure-Activity Relationship; Thylakoids
• ISSN: 1040-4651; 1532-298X
• DOI: 10.1105/tpc.1.3.361

Plants and green algae can develop resistance to herbicides that block photosynthesis by competing with quinones in binding to the chloroplast photosystem II (PSII) D1 polypeptide. Because numerous herbicide-resistant mutants of Chlamydomonas reinhardtii with different patterns of resistance to such herbicides are readily isolated, this system provides a powerful tool for examining the interactions of herbicides and endogenous quinones with the photosynthetic membrane, and for studying the structure-function relationship of the D1 protein with respect to PSII electron transfer. Here we report the results of DNA sequence analysis of the D1 gene from four mutants not previously characterized at the molecular level, the correlation of changes in specific amino acid residues of the D1 protein with levels of resistance to the herbicides atrizine, diuron, and bromacil, and the kinetics of fluorescence decay for each mutant, which show that changes at two different amino acid residues dramatically slow PSII electron transfer. Our analyses, which identify a region of 57 amino acids of the D1 polypeptide involved in herbicide binding and which define a D1 binding niche for the second quinone acceptor, Q B of PSII, provide a strong basis of support for structural and functional models of the PSII reaction center.