Redox regulation of chloroplast transcription.
Chloroplasts are the important plant cell organelles where photosynthesis takes place. Throughout this process, reaction center proteins are degraded and subsequently replenished by redox-responsive gene expression. In addition to well defined posttranscriptional mechanisms at the RNA and protein level, the transcription of chloroplast DNA into RNA precursors has been a focal point of studies in this area. Evidence has become available for a central role of a redox-responsive protein kinase named plastid transcription kinase (PTK) because of its association with the chloroplast transcription complex. The recent cloning of the PTK gene has resulted in a full-length cDNA for a protein related to the catalytic alpha subunit of nucleocytoplasmic casein kinase (CK2), yet with an additional chloroplast transit peptide. The corresponding protein, termed cpCK2alpha, was shown to be associated with the major organellar RNA polymerase, PEP-A. Both authentic PTK and recombinant cpCK2alpha have comparable general properties in vitro, and both are subject to regulation by the redox-reactive reagent glutathione. Based on the physical and functional equivalence, it is anticipated that the cloned protein can help clarify the functional role of the transcription kinase in vivo, including the identification of interaction partners at the interface between photosynthetic redox signaling and gene expression.
Link
Gerhard
G
Department of Plant Cell Physiology and Molecular Biology, University of Bochum, D-44780 Bochum, Germany. gerhard.link@ruhr-uni-bochum.de
D000595:Amino Acid Sequence; D047390:Casein Kinase II; D047388:Casein Kinases; D002467:Cell Nucleus / Q000378:metabolism; D002736:Chloroplasts / Q000378:metabolism / Q000502:physiology*; D003593:Cytoplasm / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D018076:DNA, Complementary / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D005978:Glutathione / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D018521:Plant Physiological Phenomena; D018087:Plastids / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D014158:Transcription, Genetic
D018076:DNA, Complementary; D011994:Recombinant Proteins; D004247:DNA; D011494:Protein Kinases; D047390:Casein Kinase II; D047388:Casein Kinases; D017346:Protein Serine-Threonine Kinases; D005978:Glutathione