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Photosynth Res. 2004;82(3):339-49. doi: 10.1007/s11120-004-4213-6.

Structure, circadian regulation and bioinformatic analysis of the unique sigma factor gene in Chlamydomonas reinhardtii.

Photosynthesis research

Matthew L Carter, Annette C Smith, Hirokazu Kobayashi, Saul Purton, David L Herrin

Affiliations

  1. Section Molecular Cell and Developmental Biology and Institute for Cellular and Molecular Biology, University of Texas at Austin, 1 University Station A6700, Austin, TX, 78712, USA, [email protected].

PMID: 16143845 DOI: 10.1007/s11120-004-4213-6

Abstract

In higher plants, the transcription of plastid genes is mediated by at least two types of RNA polymerase (RNAP); a plastid-encoded bacterial RNAP in which promoter specificity is conferred by nuclear-encoded sigma factors, and a nuclear-encoded phage-like RNAP. Green algae, however, appear to possess only the bacterial enzyme. Since transcription of much, if not most, of the chloroplast genome in Chlamydomonas reinhardtii is regulated by the circadian clock and the nucleus, we sought to identify sigma factor genes that might be responsible for this regulation. We describe a nuclear gene (RPOD) that is predicted to encode an 80 kDa protein that, in addition to a predicted chloroplast transit peptide at the N-terminus, has the conserved motifs (2.1- 4.2) diagnostic of bacterial sigma-70 factors. We also identified two motifs not previously recognized for sigma factors, adjacent PEST sequences and a leucine zipper, both suggested to be involved in protein-protein interactions. PEST sequences were also found in approximately 40% of sigma factors examined, indicating they may be of general significance. Southern blot hybridization and BLAST searches of the genome and EST databases suggest that RPODmay be the only sigma factor gene in C. reinhardtii. The levels of RPODmRNA increased 2- 3-fold in the mid-to-late dark period of light-dark cycling cells, just prior to, or coincident with, the peak in chloroplast transcription. Also, the dark-period peak in RPOD mRNA persisted in cells shifted to continuous light or continuous dark for at least one cycle, indicating that RPODis under circadian clock control. These results suggest that regulation of RPODexpression contributes to the circadian clock's control of chloroplast transcription.

References

  1. Biochimie. 2000 Jun-Jul;82(6-7):537-48 - PubMed
  2. Proc Natl Acad Sci U S A. 1996 Mar 19;93(6):2488-92 - PubMed
  3. Protein Sci. 1999 May;8(5):978-84 - PubMed
  4. Science. 2000 Dec 15;290(5499):2110-3 - PubMed
  5. Am Nat. 1999 Oct;154(S4):S164-S177 - PubMed
  6. Plant J. 2002 Jul;31(2):199-209 - PubMed
  7. Biotechniques. 1988 Mar;6(3):196-7, 199-200 - PubMed
  8. J Mol Biol. 2000 Jul 21;300(4):1005-16 - PubMed
  9. Plant Cell Physiol. 1999 Aug;40(8):832-42 - PubMed
  10. Nucleic Acids Res. 1998 Jan 15;26(2):415-9 - PubMed
  11. Nucleic Acids Res. 2004 Jun 29;32(11):3435-45 - PubMed
  12. Int Rev Cytol. 1999;190:1-59 - PubMed
  13. Proc Natl Acad Sci U S A. 1997 Dec 23;94(26):14948-53 - PubMed
  14. Science. 1988 Nov 18;242(4881):1040-2 - PubMed
  15. Plant J. 1993 Feb;3(2):213-9 - PubMed
  16. DNA Res. 1999 Dec 31;6(6):369-73 - PubMed
  17. Plant Physiol. 1994 Feb;104(2):753-9 - PubMed
  18. Mol Cell Biol Res Commun. 1999 Apr;1(1):14-20 - PubMed
  19. Plant Mol Biol. 2000 Dec;44(6):699-709 - PubMed
  20. Nucleic Acids Res. 1998 Jun 1;26(11):2740-6 - PubMed
  21. J Mol Biol. 1990 Oct 5;215(3):403-10 - PubMed
  22. FEBS Lett. 2000 Sep 8;481(1):47-52 - PubMed
  23. Methods Enzymol. 1996;266:525-39 - PubMed
  24. Gene. 2000 Dec 31;261(2):221-8 - PubMed
  25. Eur J Biochem. 2002 Jul;269(13):3329-37 - PubMed
  26. Proc Natl Acad Sci U S A. 1996 Feb 6;93(3):996-1000 - PubMed
  27. Plant Physiol. 2003 Feb;131(2):401-8 - PubMed
  28. Trends Biochem Sci. 1996 Jul;21(7):267-71 - PubMed
  29. Biochim Biophys Acta. 1990 Jul 30;1049(3):311-7 - PubMed
  30. Plant Mol Biol. 2001 Oct;47(3):353-66 - PubMed
  31. Proc Natl Acad Sci U S A. 1999 Apr 27;96(9):5316-21 - PubMed
  32. Plant Mol Biol. 1997 May;34(2):181-9 - PubMed
  33. Plant Mol Biol. 1994 Oct;26(2):557-69 - PubMed
  34. Genome Biol. 2003;4(1):203 - PubMed
  35. Mol Cell Biol. 1998 Dec;18(12):7235-42 - PubMed
  36. J Cell Biol. 1986 Nov;103(5):1837-45 - PubMed
  37. FEBS Lett. 1999 May 28;451(3):275-8 - PubMed
  38. Nucleic Acids Res. 1994 Nov 11;22(22):4673-80 - PubMed
  39. Nucleic Acids Res. 2001 Aug 15;29(16):E82 - PubMed
  40. Proc Natl Acad Sci U S A. 2000 Dec 19;97(26):14813-8 - PubMed
  41. EMBO J. 2001 Apr 2;20(7):1765-73 - PubMed
  42. Plant Cell Physiol. 2001 Oct;42(10):1034-43 - PubMed
  43. Proc Natl Acad Sci U S A. 1976 Nov;73(11):3961-5 - PubMed

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