title: Genes encoding the alpha-carboxyltransferase subunit of acetyl-CoA carboxylase from Brassica napus and parental species: cloning, expression patterns, and evolution.
abstract: Heteromeric acetyl coenzyme A carboxylase (ACCase), a rate-limiting enzyme in fatty acid biosynthesis in dicots, is a multi-enzyme complex consisting of biotin carboxylase, biotin carboxyl carrier protein, and carboxyltransferase (alpha-CT and beta-CT). In the present study, four genes encoding alpha-CT were cloned from Brassica napus, and two were cloned from each of the two parental species, B. rapa and B. oleracea. Comparative and cluster analyses indicated that these genes were divided into two major groups. The major divergence between group-1 and group-2 occurred in the second intron. Group-2 alpha-CT genes represented the ancestral form in the genus Brassica. The divergence of group-1 and group-2 genes occurred in their common ancestor 12.96-17.78 million years ago (MYA), soon after the divergence of Arabidopsis thaliana and Brassica (15-20 MYA). This time of divergence is identical to that reported for the paralogous subgenomes of diploid Brassica species (13-17 MYA). Real-time reverse transcription PCR revealed that the expression patterns of the two groups of genes were similar in different organs, except in leaves. To better understand the regulation and evolution of alpha-CT genes, promoter regions from two sets of orthologous gene copies from B. napus, B. rapa, and B. oleracea were cloned and compared. The function of the promoter of gene Bnalpha-CT-1-1 in group-1 and gene Bnalpha-CT-2-1 in group-2 was examined by assaying beta-glucuronidase activity in transgenic A. thaliana. Our results will be helpful in elucidating the evolution and regulation of ACCase in oilseed rape.
authors.affiliation: Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Zhi-Guo
authors.initials: ZG
authors.lastname: Li
authors.forename: Wei-Bo
authors.initials: WB
authors.lastname: Yin
authors.forename: Huan
authors.initials: H
authors.lastname: Guo
authors.forename: Li-Ying
authors.initials: LY
authors.lastname: Song
authors.forename: Yu-Hong
authors.initials: YH
authors.lastname: Chen
authors.forename: Rong-Zhan
authors.initials: RZ
authors.lastname: Guan
authors.forename: Jing-Qiao
authors.initials: JQ
authors.lastname: Wang
authors.forename: Richard R-C
authors.initials: RR
authors.lastname: Wang
authors.forename: Zan-Min
authors.initials: ZM
authors.lastname: Hu
mesh_terms: D024506:5' Flanking Region / Q000235:genetics; D000103:Acetyl-CoA Carboxylase / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D029688:Brassica napus / Q000201:enzymology / Q000235:genetics*; D029741:Brassica rapa / Q000201:enzymology / Q000235:genetics; D003001:Cloning, Molecular; D018744:DNA, Plant / Q000737:chemistry / Q000235:genetics*; D019143:Evolution, Molecular; D018628:Gene Dosage; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism; D017422:Sequence Analysis, DNA; D013045:Species Specificity
chemical_list: D018744:DNA, Plant; D010940:Plant Proteins; D021122:Protein Subunits; D000103:Acetyl-CoA Carboxylase