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Gene Review

psbA  -  photosystem II protein D1

Chlamydomonas reinhardtii

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Disease relevance of psbA

  • RB47 expressed and purified from Escherichia coli binds to the psbA 5' UTR with similar specificity and affinity as RB47 isolated from C. reinhardtii chloroplasts [1].

High impact information on psbA

  • Examination of this processing event in C. reinhardtii strains containing mutations within the chloroplast or nuclear genomes that block psbA translation reveals a correlation between processing and ribosome association [2].
  • One of the membrane-associated RNA-binding proteins appears to be RB47, which has been reported to be a specific activator of psbA mRNA translation [3].
  • A second element required for high levels of psbA translation is located adjacent to and upstream of the Shine-Dalgarno sequence, and maps to the location on the RNA previously identified as the site of message-specific protein binding [4].
  • These data suggest that the translation of psbA mRNA is attenuated by phosphorylation of the mRNA-binding protein complex in response to a rise in the stromal concentration of ADP upon transfer of cells to dark [5].
  • One of these elements is a Shine-Dalgarno consensus sequence, which is necessary for ribosome association and psbA translation [4].

Biological context of psbA


Anatomical context of psbA

  • These data suggest a mechanism for translational activation of the chloroplast psbA mRNA in which an RNA element containing the ribosome-binding site is bound by message-specific RNA binding proteins allowing for increased ribosome association and translation initiation [4].
  • A chloroplast RNA binding protein from stromal thylakoid membranes specifically binds to the 5' untranslated region of the psbA mRNA [10].
  • Transcripts containing the 5' untranslated regions of the plastid genes psbA and psbB from higher plants are unstable in Chlamydomonas reinhardtii chloroplasts [11].

Associations of psbA with chemical compounds

  • We have identified a serine/threonine protein phosphotransferase, associated with the psbA mRNA-binding complex, that utilizes the beta-phosphate of ADP to phosphorylate and inactivate psbA mRNA-binding in vitro [5].
  • The light-induced increase in psbA pre-RNA processing was abolished by inhibitors of photosynthetic electron transport, but not by the ATP synthesis inhibitor, carbonylcyanide m-chlorophenylhydrazone, which actually promoted pre-RNA processing in the dark [12].
  • This effect was shown to be mainly transcriptional, and not restricted to tufA, as transcription of other chloroplast-encoded genes were cycloheximide-sensitive, although not all equally (psbA showed no more than 40% inhibition) [13].

Other interactions of psbA

  • For comparison, the effects of darkness and antibiotics on the steady state levels of psbA, rbcL, and 16S rRNA were also studied [14].
  • Light-regulated translation continues to operate in chimeric mRNAs containing the 5'-UTR of either the psbA or psbD mRNAs, despite translation of these two chimeric mRNAs at very different efficiencies, suggesting that translational efficiency and light-regulated translation are separate events [15].

Analytical, diagnostic and therapeutic context of psbA

  • This chimeric holoenzyme specifically bound the spinach psbA and Chlamydomonas rrn16 promoters in gel mobility shift assays and exhibited specific transcription initiation from the same two promoters, providing evidence for the role of CrRpoD as a functional transcription factor [16].
  • To analyse possible functions of these introns and to generate a mutant for simplified psbA gene manipulations, a psbA cDNA fragment was introduced into a psbA deletion mutant using the biolistic transformation method [17].
  • We have constructed a vector for site-directed mutagenesis of the chloroplast psbA gene encoding D1 of the green alga, Chlamydomonas reinhardtii [18].
  • Radioactive labelling and Northern blotting demonstrated that the interruption of the Calvin cycle suppressed the synthesis de novo of chloroplast proteins, such as the D1 and D2 proteins, but did not affect the levels of psbA and psbD mRNAs [19].
  • Results from RT-PCR amplification indicated that the chlL gene in C. protothecoides contained a 951-bp intron, and the splicing catalytic core structure was similar to that of the light-regulated intron in the psbA gene of Chlamydomonas [20].


  1. A poly(A) binding protein functions in the chloroplast as a message-specific translation factor. Yohn, C.B., Cohen, A., Danon, A., Mayfield, S.P. Proc. Natl. Acad. Sci. U.S.A. (1998) [Pubmed]
  2. Processing of the psbA 5' untranslated region in Chlamydomonas reinhardtii depends upon factors mediating ribosome association. Bruick, R.K., Mayfield, S.P. J. Cell Biol. (1998) [Pubmed]
  3. Low density membranes are associated with RNA-binding proteins and thylakoids in the chloroplast of Chlamydomonas reinhardtii. Zerges, W., Rochaix, J.D. J. Cell Biol. (1998) [Pubmed]
  4. Translation of the psbA mRNA of Chlamydomonas reinhardtii requires a structured RNA element contained within the 5' untranslated region. Mayfield, S.P., Cohen, A., Danon, A., Yohn, C.B. J. Cell Biol. (1994) [Pubmed]
  5. ADP-dependent phosphorylation regulates RNA-binding in vitro: implications in light-modulated translation. Danon, A., Mayfield, S.P. EMBO J. (1994) [Pubmed]
  6. Site-specific mutagenesis of the D1 subunit of photosystem II in wild-type Chlamydomonas. Przibilla, E., Heiss, S., Johanningmeier, U., Trebst, A. Plant Cell (1991) [Pubmed]
  7. Minimal Extent of Sequence Homology Required for Homologous Recombination at the psbA Locus in Chlamydomonas reinhardtii Chloroplasts using PCR-generated DNA Fragments. Dauvillee, D., Hilbig, L., Preiss, S., Johanningmeier, U. Photosyn. Res. (2004) [Pubmed]
  8. Self-splicing of the Chlamydomonas chloroplast psbA introns. Herrin, D.L., Bao, Y., Thompson, A.J., Chen, Y.F. Plant Cell (1991) [Pubmed]
  9. Two group I introns with long internal open reading frames in the chloroplast psbA gene of Chlamydomonas moewusii. Turmel, M., Boulanger, J., Lemieux, C. Nucleic Acids Res. (1989) [Pubmed]
  10. A chloroplast RNA binding protein from stromal thylakoid membranes specifically binds to the 5' untranslated region of the psbA mRNA. Ossenbühl, F., Hartmann, K., Nickelsen, J. Eur. J. Biochem. (2002) [Pubmed]
  11. Transcripts containing the 5' untranslated regions of the plastid genes psbA and psbB from higher plants are unstable in Chlamydomonas reinhardtii chloroplasts. Nickelsen, J. Mol. Gen. Genet. (1999) [Pubmed]
  12. Evidence for light/redox-regulated splicing of psbA pre-RNAs in Chlamydomonas chloroplasts. Deshpande, N.N., Bao, Y., Herrin, D.L. RNA (1997) [Pubmed]
  13. Requirement for cytoplasmic protein synthesis during circadian peaks of transcription of chloroplast-encoded genes in Chlamydomonas. Kawazoe, R., Hwang, S., Herrin, D.L. Plant Mol. Biol. (2000) [Pubmed]
  14. Darkness and antibiotics increase the steady-state transcripts of the elongation factor gene (tuf) in Chlamydomonas reinhardtii. Silk, G.W., Wu, M. Curr. Genet. (1988) [Pubmed]
  15. Contribution of 5'- and 3'-untranslated regions of plastid mRNAs to the expression of Chlamydomonas reinhardtii chloroplast genes. Barnes, D., Franklin, S., Schultz, J., Henry, R., Brown, E., Coragliotti, A., Mayfield, S.P. Mol. Genet. Genomics (2005) [Pubmed]
  16. Chlamydomonas reinhardtii encodes a single sigma(70)-like factor which likely functions in chloroplast transcription. Bohne, A.V., Irihimovitch, V., Weihe, A., Stern, D.B. Curr. Genet. (2006) [Pubmed]
  17. Construction of a Chlamydomonas reinhardtii mutant with an intronless psbA gene. Johanningmeier, U., Heiss, S. Plant Mol. Biol. (1993) [Pubmed]
  18. Genetic engineering of the processing site of D1 precursor protein of photosystem II reaction center in Chlamydomonas reinhardtii. Takahashi, Y., Utsumi, K., Yamamoto, Y., Hatano, A., Satoh, K. Plant Cell Physiol. (1996) [Pubmed]
  19. Interruption of the Calvin cycle inhibits the repair of Photosystem II from photodamage. Takahashi, S., Murata, N. Biochim. Biophys. Acta (2005) [Pubmed]
  20. Characterization of three genes encoding the subunits of light-independent protochlorophyllide reductase in Chlorella protothecoides CS-41. Shi, C., Shi, X. Biotechnol. Prog. (2006) [Pubmed]
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