title: Tissue-specific and developmental-specific expression of an Arabidopsis thaliana gene encoding the lipoamide dehydrogenase component of the plastid pyruvate dehydrogenase complex.
abstract: We describe an Arabidopsis thaliana gene, ptlpd2, which codes for a protein with high amino acid similarity to lipoamide dehydrogenases (LPDs) from diverse species. Ptlpd2 codes for a precursor protein possessing an N-terminal extension predicted to be a plastid-targeting signal. Expression of the ptlpd2 cDNA in Escherichia coli showed the encoded protein possessed the predicted LPD activity. PTLPD2 protein, synthesized in vitro, was efficiently imported into isolated chloroplasts of Pisum sativum and shown to be located in the stroma. In addition, fusion proteins containing the predicted transit peptide of PTLPD2 or the entire protein fused at the N-terminus with the green fluorescent protein (GFP), showed accumulation in vivo in chloroplasts but not in mitochondria of A. thaliana. Expression of ptlpd2 was investigated by introducing ptlpd2 promoter-beta-glucuronidase (GUS) gene fusions into Nicotiana tabacum. GUS expression was observed in seeds, flowers, root tips and young leaves. GUS activity was highest in mature seeds, decreased on germination and increased again in young leaves. Expression was also found to be temporally regulated in pollen grains where it was highest in mature grains at dehiscence. Database searches on ptlpd2 sequences identified a second A. thaliana gene encoding a putative plastidial LPD and two genes encoding proteins with high similarity to the mitochondrial LPD of P. sativum.
authors.affiliation: Department of Genetics, Trinity College, Dublin, Ireland.
authors.forename: S C
authors.initials: SC
authors.lastname: Drea
authors.forename: R M
authors.initials: RM
authors.lastname: Mould
authors.forename: J M
authors.initials: JM
authors.lastname: Hibberd
authors.forename: J C
authors.initials: JC
authors.lastname: Gray
authors.forename: T A
authors.initials: TA
authors.lastname: Kavanagh
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D017931:DNA Primers; D008058:Dihydrolipoamide Dehydrogenase / Q000737:chemistry / Q000235:genetics*; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D008928:Mitochondria; D008969:Molecular Sequence Data; D030821:Plants, Genetically Modified; D010947:Plants, Toxic; D018087:Plastids / Q000201:enzymology*; D011768:Pyruvate Dehydrogenase Complex / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana / Q000235:genetics
chemical_list: D017931:DNA Primers; D011768:Pyruvate Dehydrogenase Complex; D008058:Dihydrolipoamide Dehydrogenase