title: QUASIMODO 3 (QUA3) is a putative homogalacturonan methyltransferase regulating cell wall biosynthesis in Arabidopsis suspension-cultured cells.
abstract: Pectins are complex polysaccharides that are essential components of the plant cell wall. In this study, a novel putative Arabidopsis S-adenosyl-L-methionine (SAM)-dependent methyltransferase, termed QUASIMODO 3 (QUA3, At4g00740), has been characterized and it was demonstrated that it is a Golgi-localized, type II integral membrane protein that functions in methylesterification of the pectin homogalacturonan (HG). Although transgenic Arabidopsis seedlings with overexpression, or knock-down, of QUA3 do not show altered phenotypes or changes in pectin methylation, this enzyme is highly expressed and abundant in Arabidopsis suspension-cultured cells. In contrast, in cells subjected to QUA3 RNA interference (RNAi) knock-down there is less pectin methylation as well as altered composition and assembly of cell wall polysaccharides. Taken together, these observations point to a Golgi-localized QUA3 playing an essential role in controlling pectin methylation and cell wall biosynthesis in Arabidopsis suspension cell cultures.
authors: School of Life Sciences, Centre for Cell and Developmental Biology, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.
authors: Yansong
authors: Y
authors: Miao
authors: Hong-Ye
authors: HY
authors: Li
authors: Jinbo
authors: J
authors: Shen
authors: Junqi
authors: J
authors: Wang
authors: Liwen
authors: L
authors: Jiang
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000145:classification / Q000201:enzymology* / Q000235:genetics / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000737:chemistry / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D002478:Cells, Cultured; D019143:Evolution, Molecular; D006056:Golgi Apparatus / Q000235:genetics; D008745:Methylation; D008780:Methyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D010368:Pectins / Q000096:biosynthesis; D010802:Phylogeny; D021381:Protein Transport; D016415:Sequence Alignment
chemical_list: D029681:Arabidopsis Proteins; D010368:Pectins; D008780:Methyltransferases; C569923:QUA3 protein, Arabidopsis; C003181:polygalacturonic acid