Characterization of the plastid-encoded carboxyltransferase subunit (accD) gene of potato

Plant Cell and Molecular Biology Research Unit, Korea Research Institute of Bioscience and Biotechnology, Daejeon, Korea.
Molecules and Cells (Impact Factor: 2.24). 07/2004; 17(3):422-9.
Source: PubMed

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.

Download full-text


Available from: Jae-Wook Bang, Aug 10, 2015
  • Source
    • "While the coding sequences of T. aureum and T. grandiflorum share pairwise identity of 75.4% over their entire length (not shown), at the protein level local identity reached well into the 90% range. The C-terminal catalytic domain (PLI- IVCASGGARMQE; Lee et al., 2004) required for ACCase function is present and contained within a larger block of 80 residues with 91.3% identity between the two Trifolium species and 90.4% among the two and the Cicer arietinum pt-accD (Figure S3). Extensive searching of public genomic resources (see methods) revealed the presence of an accD open reading frame in the nuclear genomes of Medicago truncatula and Cicer arietinum. "
    [Show abstract] [Hide abstract]
    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
  • Source
    • "Within the Campanulaceae, the 39 end of n-accD that corresponds to the accD carboxylase domain is highly conserved compared with the 59 end of the gene, consistent with it also encoding a functional domain in this nuclear gene. Second, the carboxyltransferase domain of the nuclear protein maintains the " PLIIVCASGGARMQE " motif that is considered to be the accD putative catalytic site (Lee et al., 2004). Figure 6. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Eukaryotic cells originated when an ancestor of the nucleated cell engulfed bacterial endosymbionts that gradually evolved into the mitochondrion and the chloroplast. Soon after these endosymbiotic events, thousands of ancestral prokaryotic genes were functionally transferred from the endosymbionts to the nucleus. This process of functional gene relocation, now rare in eukaryotes, continues in angiosperms. In this article, we show that the chloroplastic accD gene that is present in the plastome of most angiosperms has been functionally relocated to the nucleus in the Campanulaceae. Surprisingly, the nucleus-encoded accD transcript is considerably smaller than the plastidic version, consisting of little more than the carboxylase domain of the plastidic accD gene fused to a coding region encoding a plastid targeting peptide. We verified experimentally the presence of a chloroplastic transit peptide by showing that the product of the nuclear accD fused to GFP was imported in the chloroplasts. The nuclear gene regulatory elements that enabled the erstwhile plastidic gene to become functional in the nuclear genome were identified and the evolution of the intronic and exonic sequences in the nucleus is described. Relocation and truncation of the accD gene is a remarkable example of the processes underpinning endosymbiotic evolution.
    Plant physiology 02/2013; 161. DOI:10.1104/pp.113.214528 · 7.39 Impact Factor
  • Source
    • "Primer extension reactions were carried out with total leaf or tuber RNA samples using the Primer Extension System (Promega), as described by Allison and Maliga (1995) and Lee et al. (2004). Primers were labeled with [g- 32 P]ATP using T4 polynucleotide kinase. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Gene expression in nongreen plastids is largely uncharacterized. To compare gene expression in potato (Solanum tuberosum) tuber amyloplasts and leaf chloroplasts, amounts of transcripts of all plastid genes were determined by hybridization to plastome arrays. Except for a few genes, transcript accumulation was much lower in tubers compared with leaves. Transcripts of photosynthesis-related genes showed a greater reduction in tubers compared with leaves than transcripts of genes for the genetic system. Plastid genome copy number in tubers was 2- to 3-fold lower than in leaves and thus cannot account for the observed reduction of transcript accumulation in amyloplasts. Both the plastid-encoded and the nucleus-encoded RNA polymerases were active in potato amyloplasts. Transcription initiation sites were identical in chloroplasts and amyloplasts, although some differences in promoter utilization between the two organelles were evident. For some intron-containing genes, RNA splicing was less efficient in tubers than in leaves. Furthermore, tissue-specific differences in editing of ndh transcripts were detected. Hybridization of the plastome arrays with RNA extracted from polysomes indicated that, in tubers, ribosome association of transcripts was generally low. Nevertheless, some mRNAs, such as the transcript of the fatty acid biosynthesis gene accD, displayed relatively high ribosome association. Selected nuclear genes involved in plastid gene expression were generally significantly less expressed in tubers than in leaves. Hence, compared with leaf chloroplasts, gene expression in tuber amyloplasts is much lower, with control occurring at the transcriptional, posttranscriptional, and translational levels. Candidate regulatory sequences that potentially can improve plastid (trans)gene expression in amyloplasts have been identified.
    Plant physiology 07/2009; 150(4):2030-44. DOI:10.1104/pp.109.140483 · 7.39 Impact Factor
Show more