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Abstract Detail

Intracellular Signaling

Cottage, Amanda [1], Mott, Ellie [1], Wang, Jun-Hui [1], Sullivan, James [1], MacLean, Dan [1], Tran, Linh [2], Choy, Mun-Kit [1], Newell, Christine [1], Kavanagh, Tony [3], Aspinall, Sue [1], Gray, John C. [1].

GUN1 (GENOMES UNCOUPLED1) encodes a pentatricopeptide repeat (PPR) protein involved in plastid protein synthesis-responsive retrograde signaling to the nucleus.

Plastid-to-nucleus signaling coordinates the expression of nuclear and plastid genes required for the assembly of functional chloroplasts. We have isolated new alleles of gun1 (genomes uncoupled1) by screening EMS and X-ray mutagenised lines of Arabidopsis thaliana containing the GFP reporter gene under the control of a tobacco RbcS promoter for GFP expression in the presence of norflurazon, a carotenoid biosynthesis inhibitor, or lincomycin, an inhibitor of plastid translation. gun1 mutants were able to express photosynthesis-related nuclear genes in the presence of lincomycin, unlike other gun (gun2-gun5) mutants. Microarray analysis identified CA1 (CARBONIC ANHYDRASE1) as the gene most responsive to lincomycin in 7-day-old wild-type seedlings, and a CA1 promoter::GFP reporter gene was used to map the gun1 mutation to a 224 kb region on chromosome 2. Sequencing of candidate genes identified GUN1 as At2g31400, encoding a pentatricopeptide repeat (PPR) protein of 918 amino acid residues, with a putative N-terminal plastid-targeting sequence of 41 amino acid residues, 10 copies of the PPR motif and an SMR (small MutS-related) domain with possible nuclease activity near the C-terminus. gun1-100 contained a point mutation creating a stop codon at amino acid 56, whereas gun1-1 contained a point mutation resulting in an Ala259Val change near the first PPR motif. The identification of GUN1 should facilitate further characterization of additional components of the plastid protein-synthesis-responsive signaling pathway.

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1 - Cambridge University, Department of Plant Sciences
2 - Cambridge University, Department of Plant Sciences, Downing Site, Tennis Court Road, Cambridge, CB2 3EA, U.K.
3 - Trinity College, Dublin, Department of Genetics

retrograde regulation.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P33026
Abstract ID:2586

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