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Gene Review

psbAI  -  photosystem II D1 protein

Synechococcus elongatus PCC 6301

 
 
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Disease relevance of psbAI

  • A reporter gene assay revealed that promoters derived from Synechococcus PCC7942 (S.7942) psbAI and Synechocystis PCC6803 (S.6803) psbAII were suitable for the expression of foreign ribulose-bisphosphate carboxylase (RuBisCO; EC 4.1.1.39) in S.7942 cells [1].
  • We isolated mutants affected in the circadian expression of the psbAI gene in Synechococcus sp. strain PCC 7942 using a strategy that tags the genomic locus responsible for the mutant phenotype [2].
  • This suggests a similarity to the divergent psbAI gene from Synechocystis, whose natural expression we demonstrate for the first time at a trace level similar to psbA0 in Anabaena [3].
 

High impact information on psbAI

  • Chilling or light-induced D1 exchange results from rapid loss of psbAI message coding for D1:1 and accumulation of psbAII and psbAIII messages coding for D1:2 [4].
  • The nucleotide sequences of two of the genes, psbAII and psbAIII, predict a protein having the same amino acid sequence which differs from that of the psbAI gene by 25 (out of 360) residues [5].
  • We used a psbAI 'minigene' which has a part of the coding sequence removed as a reporter gene in order to identify the cis-acting elements of the transcript that determine stability [6].
  • Electrophoretic mobility shift assays showed that the DNA sequence corresponding to the untranslated leader of the psbAI message binds one or more proteins from an S. elongatus extract [7].
  • Mutagenizing the atypical psbAI -10 element from TCTCCT to TATAAT increased the magnitude of expression from both psbAI::lacZ and psbAI::luxAB fusions but did not affect downregulation under high light [7].
 

Biological context of psbAI

  • In this paper a gene (psfR) is reported that regulates psbAI activity in Synechococcus elongatus, a unicellular photoautotrophic cyanobacterium that carries out oxygenic (plant-type) photosynthesis and exhibits global circadian regulation of gene expression [8].
  • PsfR acts (directly or indirectly) on the psbAI basal promoter region. psfR knockout mutants exhibit wild-type psbAI expression, suggesting that other factors can regulate psbAI expression in the absence of functional PsfR [8].
 

Anatomical context of psbAI

  • Form II replaced form I in the thylakoid membrane at high light despite an abundance of psbAI transcript at later time points; this may be explained by the observed faster turnover of form I than form II in the membrane [9].
  • This treatment doubled the amount of psbAII/III mRNA and the D1:2 protein in membranes but decreased the amount of psbAI messages and the D1:1 protein [10].
 

Associations of psbAI with chemical compounds

  • The amount of psbAI mRNA and that of D1:1 protein in cells grown with IPTG was three times and two times higher, respectively [11].
  • The rate of disappearance of the psbAI transcript in cells shifted to high light was diminished when either transcription or translation was blocked by rifampin or chloramphenicol, suggesting that accelerated degradation of the message requires de novo synthesis of a protein factor [12].
  • The presence of these domains and the absence of a detectable conserved DNA-binding domain suggest that PsfR may regulate psbAI expression via protein-protein interactions or GGDEF activity (the production of cyclic dinucleotides) rather than direct interaction with the psbAI promoter [8].
  • To demonstrate the utility of this method, a cassette consisting of the wild-type rps12 gene and a kan gene conferring kanamycin resistance was integrated into the rps12-R43 mutant at the psbAI locus encoding photosystem II D1 protein, resulting in streptomycin-sensitive merodiploids [13].
  • Construction and analysis of a recombinant cyanobacterium expressing a chromosomally inserted gene for an ethylene-forming enzyme at the psbAI locus [14].
 

Regulatory relationships of psbAI

  • Strong light and low temperature have been shown to induce the expression of psbAII/III genes and down-regulate the expression of psbAI gene [15].

References

  1. Expression of foreign type I ribulose-1,5-bisphosphate carboxylase/ oxygenase (EC 4.1.1.39) stimulates photosynthesis in cyanobacterium Synechococcus PCC7942 cells. Iwaki, T., Haranoh, K., Inoue, N., Kojima, K., Satoh, R., Nishino, T., Wada, S., Ihara, H., Tsuyama, S., Kobayashi, H., Wadano, A. Photosyn. Res. (2006) [Pubmed]
  2. A sigma factor that modifies the circadian expression of a subset of genes in cyanobacteria. Tsinoremas, N.F., Ishiura, M., Kondo, T., Andersson, C.R., Tanaka, K., Takahashi, H., Johnson, C.H., Golden, S.S. EMBO J. (1996) [Pubmed]
  3. Cyanobacterial psbA families in Anabaena and Synechocystis encode trace, constitutive and UVB-induced D1 isoforms. Sicora, C.I., Appleton, S.E., Brown, C.M., Chung, J., Chandler, J., Cockshutt, A.M., Vass, I., Campbell, D.A. Biochim. Biophys. Acta (2006) [Pubmed]
  4. Electron transport regulates exchange of two forms of photosystem II D1 protein in the cyanobacterium Synechococcus. Campbell, D., Zhou, G., Gustafsson, P., Oquist, G., Clarke, A.K. EMBO J. (1995) [Pubmed]
  5. Expression of a family of psbA genes encoding a photosystem II polypeptide in the cyanobacterium Anacystis nidulans R2. Golden, S.S., Brusslan, J., Haselkorn, R. EMBO J. (1986) [Pubmed]
  6. mRNA stability is regulated by a coding-region element and the unique 5' untranslated leader sequences of the three Synechococcus psbA transcripts. Kulkarni, R.D., Golden, S.S. Mol. Microbiol. (1997) [Pubmed]
  7. Functional elements of the strong psbAI promoter of Synechococcus elongatus PCC 7942. Nair, U., Thomas, C., Golden, S.S. J. Bacteriol. (2001) [Pubmed]
  8. PsfR, a factor that stimulates psbAI expression in the cyanobacterium Synechococcus elongatus PCC 7942. Thomas, C., Andersson, C.R., Canales, S.R., Golden, S.S. Microbiology (Reading, Engl.) (2004) [Pubmed]
  9. Adaptation to high light intensity in Synechococcus sp. strain PCC 7942: regulation of three psbA genes and two forms of the D1 protein. Kulkarni, R.D., Golden, S.S. J. Bacteriol. (1994) [Pubmed]
  10. Over-production of the D1:2 protein makes Synechococcus cells more tolerant to photoinhibition of photosystem II. Soitamo, A.J., Zhou, G., Clarke, A.K., Oquist, G., Gustafsson, P., Aro, E.M. Plant Mol. Biol. (1996) [Pubmed]
  11. Over-production of the D1 protein of photosystem II reaction centre in the cyanobacterium Synechococcus sp. PCC 7942. Soitamo, A.J., Zhou, G., Clarke, A.K., Oquist, G., Aro, E.M., Gustafsson, P. Plant Mol. Biol. (1994) [Pubmed]
  12. Transcriptional and posttranscriptional components of psbA response to high light intensity in Synechococcus sp. strain PCC 7942. Kulkarni, R.D., Schaefer, M.R., Golden, S.S. J. Bacteriol. (1992) [Pubmed]
  13. Gene replacement in cyanobacteria mediated by a dominant streptomycin-sensitive rps12 gene that allows selection of mutants free from drug resistance markers. Matsuoka, M., Takahama, K., Ogawa, T. Microbiology (Reading, Engl.) (2001) [Pubmed]
  14. Construction and analysis of a recombinant cyanobacterium expressing a chromosomally inserted gene for an ethylene-forming enzyme at the psbAI locus. Takahama, K., Matsuoka, M., Nagahama, K., Ogawa, T. J. Biosci. Bioeng. (2003) [Pubmed]
  15. Expression of psbA genes is regulated at multiple levels in the cyanobacterium Synechococcus sp. PCC 7942. Sippola, K., Aro, E.M. Photochem. Photobiol. (2000) [Pubmed]
 
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