Intraplastidial trafficking of a phage-type RNA polymerase is mediated by a thylakoid RING-H2 protein

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 26; pp. 9123 - 9128
• Main Authors: Azevedo, Jacinthe, Courtois, Florence, Hakimi, Mohamed-Ali, Demarsy, Emilie, Lagrange, Thierry, Alcaraz, Jean-Pierre, Jaiswal, Pankaj, Maréchal-Drouard, Laurence, Lerbs-Mache, Silva
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 01.07.2008; National Acad Sciences
• Subjects: Amino Acid Sequence; Antibodies; Arabidopsis; Arabidopsis - enzymology; Arabidopsis - genetics; Arabidopsis - radiation effects; Arabidopsis Proteins; Arabidopsis Proteins - chemistry; Arabidopsis Proteins - metabolism; Arabidopsis thaliana; Bacteriophages; Bacteriophages - enzymology; binding proteins; Biochemistry, Molecular Biology; Biological Sciences; Cells; Chloroplasts; DNA-Binding Proteins; DNA-directed RNA polymerase; DNA-Directed RNA Polymerases; DNA-Directed RNA Polymerases - chemistry; DNA-Directed RNA Polymerases - metabolism; Enzymes; Etioplasts; Flowers & plants; Gene Expression Regulation, Plant; Gene Expression Regulation, Plant - radiation effects; Gene Library; Genes; Genomes; Genomics; Intracellular Membranes; Intracellular Membranes - metabolism; Intracellular Membranes - radiation effects; Life Sciences; Light; membrane proteins; Membranes; Molecular Sequence Data; Organ Specificity; Organ Specificity - radiation effects; Plastids; Promoter Regions (Genetics); Promoter Regions, Genetic - genetics; Protein Binding; Protein Binding - radiation effects; Protein Transport; Protein Transport - radiation effects; protein-protein interactions; Proteins; Ribonucleic acid; RNA; RNA, Messenger; RNA, Messenger - genetics; RNA, Messenger - metabolism; RNA, Ribosomal, 16S; RNA, Ribosomal, 16S - metabolism; Saccharomyces cerevisiae Proteins; Saccharomyces cerevisiae Proteins - metabolism; Spinach; Spinacia oleracea; thylakoid membrane proteins; Thylakoids; Thylakoids - enzymology; Thylakoids - radiation effects; Transcription Factors; Transcription Factors - metabolism; Two-Hybrid System Techniques; Vegetal Biology
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0800909105

The plastid genome of dicotyledonous plants is transcribed by three different RNA polymerases; an eubacterial-type enzyme, PEP; and two phage-type enzymes, RPOTp and RPOTmp. RPOTp plays an important role in chloroplast transcription, biogenesis, and mesophyll cell proliferation. RPOTmp fulfills a specific function in the transcription of the rrn operon in proplasts/amyloplasts during seed imbibition/germination and a more general function in chloroplasts during later developmental stages. In chloroplasts, RPOTmp is tightly associated with thylakoid membranes indicating that functional switching of RPOTmp is connected to thylakoid association. By using the yeast two-hybrid system, we have identified two proteins that interact with RPOTmp. The two proteins are very similar, both characterized by three N-terminal transmembrane domains and a C-terminal RING domain. We show that at least one of these proteins is an intrinsic thylakoid membrane protein that fixes RPOTmp on the stromal side of the thylakoid membrane, probably via the RING domain. A model is presented in which light by triggering the synthesis of the RING protein determines membrane association and functional switching of RPOTmp.