Characterization of the plastid-encoded carboxyltransferase subunit (accD) gene of potato.
ABSTRACT The plastid accD gene encoding the carboxyltransferase b subunit of acetyl-coenzyme A carboxylase (ACCase) was cloned from potato. Potato accD (saccD) is 2487 bp in length with a 614 bp 5 cent upstream promoter region and an ORF of 1524 bp, corresponding to a polypeptide of 507 amino acids. The N-terminal region lacks recognizable motifs, while the C-terminal regions contains five motifs. Among these is motif II, PLIIVCASGGARMQE, the sole motif present in all available accD sequences of plants and animals, and of E. coli, suggesting that this motif may correspond to the catalytic site. saccD has the typical prokaryotic promoter signatures, TTGACA and TATCAA, which are -35 and -10-like sequences for plastid-encoded RNA polymerase (PEP), at positions -184 and -160, respectively. However, it seems to be transcribed by the nucleus-encoded RNA polymerase because it is expressed in tuber and root, and in the dark (under crippled PEP conditions) and its transcription initiation sites do not correspond to those of PEP. saccD is expressed in all potato tissues, i.e., leaf, stem, root, and tuber, and its transcript is produced at a similar rate in the light and dark, at different developmental stages, and during growth in the presence of different sugars and carbon sources. Taken together, our results suggest that potato accD is a housekeeping gene constitutively expressed in both chloroplast and amyloplast.
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ABSTRACT: Candidate genes of multisubunit (MS) and multifunctional (MF) acetyl-CoA carboxylase (ACCase) including accB1, accB2, accC, accA, accD, and MF-ACCase were isolated from peanut by sequencing a full-length cDNA library and homology-based cloning. Primary structures of peanut ACCases were highly conserved, especially biochemical function domains, compared with other higher plants and Escherichia coli. The numbers of homologs of each ACCase gene expressed in developing seed of peanut varied from two to five. Two editing sites of peanut accD were identified by comparing genomic DNA and its corresponding cDNAs. The MS-ACCase of Arachis hypogaea and Arabidopsis thaliana shared a conservative structure of gene organization. Semiquantitative reverse transcription polymerase chain reaction analysis indicated that MS-ACCase and MF-ACCase genes were expressed in all peanut tissues examined, but their mRNA expression level were quite different. In peanut seed development, accC, accA, accD, and MF-ACCase mRNAs were expressed strongly at 60 days after pegging.Plant Molecular Biology Reporter 01/2010; 28(1):58-68. DOI:10.1007/s11105-009-0126-z · 2.37 Impact Factor
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ABSTRACT: Land plant plastid genomes (plastomes) provide a tractable model for evolutionary study in that they are relatively compact and gene dense. Among the groups that display an appropriate level of variation for structural features, the inverted-repeat-lacking clade (IRLC) of papilionoid legumes presents the potential to advance general understanding of the mechanisms of genomic evolution. Here, are presented six complete plastome sequences from economically important species of the IRLC, a lineage previously represented by only five completed plastomes. A number of characters are compared across the IRLC including gene retention and divergence, synteny, repeat structure and functional gene transfer to the nucleus. The loss of clpP intron 2 was identified in one newly sequenced member of IRLC, Glycyrrhiza glabra. Using deeply sequenced nuclear transcriptomes from two species helped clarify the nature of the functional transfer of accD to the nucleus in Trifolium, which likely occurred in the lineage leading to subgenus Trifolium. Legumes are second only to cereal crops in agricultural importance based on area harvested and total production. Genetic improvement via plastid transformation of IRLC crop species is an appealing proposition. Comparative analyses of intergenic spacer regions emphasize the need for complete genome sequences for developing transformation vectors for plastid genetic engineering of legume crops.Plant Biotechnology Journal 03/2014; DOI:10.1111/pbi.12179 · 5.68 Impact Factor
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ABSTRACT: We fully sequenced four and partially sequenced six additional plastid genomes of the model legume Medicago truncatula. Three accessions, Jemalong 2HA, Borung and Paraggio, belong to ssp. truncatula, and R108 to ssp. tricycla. We report here that the R108 ptDNA has a ∼45-kb inversion compared with the ptDNA in ssp. truncatula, mediated by a short, imperfect repeat. DNA gel blot analyses of seven additional ssp. tricycla accessions detected only one of the two alternative genome arrangements, represented by three and four accessions each. Furthermore, we found a variable number of repeats in the essential accD and ycf1 coding regions. The repeats within accD are recombinationally active, yielding variable-length insertions and deletions in the central part of the coding region. The length of ACCD was distinct in each of the 10 sequenced ecotypes, ranging between 650 and 796 amino acids. The repeats in the ycf1 coding region are also recombinationally active, yielding short indels in 10 regions of the reading frames. Thus, the plastid genome variability we report here could be linked to repeat-mediated genome rearrangements. However, the rate of recombination was sufficiently low, so that no heterogeneity of ptDNA could be observed in populations maintained by single-seed descent.DNA Research 03/2014; 21(4). DOI:10.1093/dnares/dsu007 · 4.98 Impact Factor