Naslov
Transcriptional control of photosynthesis genes: the evolutionarily conserved regulatory mechanism in plastid genome function

Autori
Puthiyaveetil, Sujith ; Ibrahim, Iskander M. ; Jeličić, Branka ; Tomašić, Ana ; Fulgosi, Hrvoje ; Allen, John F.

Izvornik
Genome biology and evolution (1759-6653) 2 (2010); 888-896

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
chloroplast sensor kinase; plastid transcription kinase; sigma factor; cytoplasmic inheritance; protein phosphorylation; Co-location for Redox Regulation (CoRR)

Sažetak
Chloroplast Sensor Kinase (CSK) is a bacterial-type sensor histidine kinase found in chloroplasts – photosynthetic plastids – in eukaryotic plants and algae. Using a yeast two-hybrid screen, we demonstrate recognition and interactions between: Chloroplast Sensor Kinase, Plastid Transcription Kinase (PTK), and a bacterial-type RNA Polymerase Sigma factor-1 (SIG-1). CSK interacts with itself, with SIG-1, and with PTK. PTK also interacts directly with SIG-1. PTK has previously been shown to catalyse phosphorylation of plastid-encoded RNA polymerase (PEP), suppressing plastid transcription non-specifically. Phospho-PTK is inactive as a PEP kinase. Here we propose that phospho-CSK acts as a PTK kinase, releasing PTK repression of chloroplast transcription, while it also acts as a SIG-1 kinase, blocking transcription specifically at the gene promoter of chloroplast photosystem I. Oxidation of the photosynthetic electron carrier plastoquinone triggers phosphoryation of CSK, inducing chloroplast photosystem II while suppressing photosystem I. CSK places photosystem gene transcription under the control of photosynthetic electron transport. This redox signalling pathway has its origin in cyanobacteria, photosynthetic prokaryotes from which chloroplasts evolved. The persistence of this mechanism in cytoplasmic organelles of photosynthetic eukaryotes is in precise agreement with the CoRR hypothesis for the function of organellar genomes: the plastid genome and its primary gene products are Co-located for Redox Regulation. Genes are retained in plastids primarily in order for their expression to be subject to this rapid and robust redox regulatory transcriptional control mechanism, while plastid genes also encode genetic system components, such as some ribosomal proteins and RNAs, that exist in order to support this primary, redox regulatory control of photosynthesis genes.

Izvorni jezik
Engleski

Znanstvena područja
Biologija

POVEZANOST RADA