PsbA gene

Mate Z, Sass L, Szekeres M, Vass I, Nagy F (1998) UV-B induced differential transcription of psbA genes encoding the D1 protein of photosystem II in the cyanobacterium Synechocystis 6803. J Biol Chem 273 17439-17444... 

Morden, C.W. and S.S. Golden (1989). psbA genes indicate common ancestry of prochlorophytes and chloroplasts. Nature, 337 382-385. 

Wildner, G.F., U. Heisterkamp, and A. Trebst (1990). Herbicide cross-resistance and mutations of the psbA gene in Chlamydomonas reinhardtii. Z. Naturforschg. Sect. CBiosci., 45 1142-1150. 

In practical terms, the Ser264 to Gly mutation causing triazine resistance reduces plant productivity and yield. This has two agronomic implications first, triazine-resistant weeds carrying this mutation are less competitive (often referred in the literature as reduced fitness) on a per plant basis as compared to their susceptible counterparts, and second, triazine-resistant rapeseed cultivars with Hie mutant psbA gene are less productive than near isogenic, susceptible cultivars (Forcella, 1987 Beversdorf et al, 1988 Hart and Stemler, 1990 Hall et al, 1996). 

Comparison of deduced amino acid sequences from psbA genes. Note the conservation of the PEST-1ike region contiguous with the a-helix-destabilizing, primary cleavage domain in the 32kDa protein. The arrow indicates the probable site where the precursor piece on the carboxy-terminus is cleaved (22). psbA sequences were compiled as follows (1) Anacystis nidulans copy I, and (2) copy II/III (41). 

Of the 869 families derived from plants collected in five populations (Table II), 33 showed at least one seedling with an intermediary fluorescence curve (Figure 1 (21)). These seedlings proved later to have the mutated psbA gene at Position 264 (19) and were moderately resistant to atrazine. They were called Type I (for intermediate level of resistance). The 33 mother plants and their corresponding seed families were called Sp. because they were special susceptible plants that produced mutant plants. 

In addition, we observed that Type I mutants have all of their psbA gene copies mutated (99.9% probability) while no heteroplasmicity was found in Sp. plants (19). This indicates that a mechanism other than a high mutation rate must work to allow the release of individual plants that have their entire chloroplast population mutated. This could be due to the control of chloroplast DNA replication directed by mitochondrial or nuclear genomes. Indeed, a sequence homology has been found between mitochondrial DNA and part of the chloroplast psbA gene. Moreover, this homologous sequence is expressed as an RNA transcript in atrazine resistant C. album only and not in the susceptible plants (30). 

Allakhverdiev SI, Nishiyama Y, Miyairi S et al. Salt stress inhibits the repair of photodamaged photosystem II by suppressing the transcription and translation of psbA genes in Synechocystis. Plant Physiol 2002 130 1443-1453. 

Tyystjarvi T, Maanpaa P, Mulo P et al. D1 Polypeptide degradation may regulate psbA gene-expression at transcriptional and translational levels in Synechocysds sp PCC-6803. Photosynth Res 1996 47 111-120. 

Mohamed A, Eriksson J, Osiewacz MD et al. Differential expression of the psbA genes in cyanobacterium Synechocystis 6803. Mol Gen Genet 1993 238 161-168. 

Golden SS, Brusslan J, Haselkorn R. Expression of a family of psbA genes encoding a photosystem II polypeptide in the cyanobacterium Anacysds nidulans R2. EMBO J 1986 5 2789-2798. 

Johanningmeier U, Heiss S. Construction of a Chlamydomonas reinhardtii mutant with an intronless psbA gene. Plant Mol Biol 1993 22(l) 91-9. 

Minagawa J, Crofts AR. A robust protocol for site-directed mutagenesis of the D1 protein of Chlamydomonas reinhardtii A PCR-spliced psbA gene in a plasmid conferring spectinomycin resistance was introduced into a psbA deletion strain. Photosynth Research 1994 42 121-132. 

This protein is product of chloroplast psbA gene, so called photogene . It is the main product of chloroplast protein synthesis in light and its mRNA is the most abundant in the chloroplasts. 

Marder JB, Mattoo AK, Edelman M. Identification and characterization of the psbA gene product The 32-kDa chloroplast membrane protein. In Weissbach A, Weissbach H, eds. Methods Enzymol, Vol. 118. New York Academic Press Inc., 1986 384-396. 

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