caa a22 4500 467895147 CHVBK 20180406152801.0 cr unu---uuuuu 170328e20061001xx s 000 0 eng 10.1007/s11103-006-9023-0 doi (NATIONALLICENCE)springer-10.1007/s11103-006-9023-0 The Arabidopsis PPDK gene is transcribed from two promoters to produce differentially expressed transcripts responsible for cytosolic and plastidic proteins [Elektronische Daten] [Kate Parsley, Julian Hibberd] Pyruvate orthophosphate dikinase (PPDK) is a critical enzyme for C4 photosynthesis, providing the primary acceptor for fixation of bicarbonate in mesophyll cells. Although first isolated in C4 plants, it is also present in C3 species. We report that the single gene encoding PPDK in Arabidopsis thaliana possesses two promoters, giving rise to two types of transcript. The longer transcript is generated from a promoter upstream of the first exon, while the shorter transcript is derived from a promoter found within the first intron of the longer form. Apart from 5′ untranslated regions, the presence of the first exon, and three missing codons at the start of the second exon in the longer form, the transcripts are identical. Fusions between the two forms of transcript and gfp showed that the longer transcript encodes a protein targeted to the chloroplast, that its first exon acts as a transit peptide, and that the smaller protein is cytosolic. Abundance of the shorter transcript, responsible for producing the cytosolic protein increases rapidly and specifically during extended dark and dark-induced senescence. Transcripts for both chloroplastic and cytosolic proteins were detectable in cotyledons, while in cauline leaves the transcript encoding the chloroplastic protein was most abundant. We propose that in cotyledons PPDK may be important in supplying PEP to gluconeogenesis, and in ageing leaves it allows remobilisation of nitrogen to supply reproductive tissue. Springer Science+Business Media B.V., 2006 Pyruvate orthophosphate dikinase nationallicence C4 photosynthesis nationallicence Arabidopsis nationallicence Nitrogen remobilisation nationallicence Evolution nationallicence Parsley Kate Department of Plant Sciences, University of Cambridge, Downing Street, CB2 3EA, Cambridge, UK aut Hibberd Julian Department of Plant Sciences, University of Cambridge, Downing Street, CB2 3EA, Cambridge, UK aut Plant Molecular Biology Kluwer Academic Publishers 62/3(2006-10-01), 339-349 0167-4412 62:3<339 2006 62 11103 https://doi.org/10.1007/s11103-006-9023-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11103-006-9023-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Parsley Kate Department of Plant Sciences, University of Cambridge, Downing Street, CB2 3EA, Cambridge, UK aut NATIONALLICENCE 700 1- Hibberd Julian Department of Plant Sciences, University of Cambridge, Downing Street, CB2 3EA, Cambridge, UK aut NATIONALLICENCE 773 0- Plant Molecular Biology Kluwer Academic Publishers 62/3(2006-10-01), 339-349 0167-4412 62:3<339 2006 62 11103 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer