title: A novel isoform of sucrose synthase is targeted to the cell wall during secondary cell wall synthesis in cotton fiber.
abstract: Sucrose (Suc) synthase (Sus) is the major enzyme of Suc breakdown for cellulose biosynthesis in cotton (Gossypium hirsutum) fiber, an important source of fiber for the textile industry. This study examines the tissue-specific expression, relative abundance, and temporal expression of various Sus transcripts and proteins present in cotton. A novel isoform of Sus (SusC) is identified that is expressed at high levels during secondary cell wall synthesis in fiber and is present in the cell wall fraction. The phylogenetic relationships of the deduced amino acid sequences indicate two ancestral groups of Sus proteins predating the divergence of monocots and dicots and that SusC sequences form a distinct branch in the phylogeny within the dicot-specific clade. The subcellular location of the Sus isoforms is determined, and it is proposed that cell wall-localized SusC may provide UDP-glucose for cellulose and callose synthesis from extracellular sugars.
authors.affiliation: Commonwealth Scientific and Industrial Research Organization Plant Industry, Canberra, Australian Capital Territory 2601, Australia.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Brill
authors.forename: Michel
authors.initials: M
authors.lastname: van Thournout
authors.forename: Rosemary G
authors.initials: RG
authors.lastname: White
authors.forename: Danny
authors.initials: D
authors.lastname: Llewellyn
authors.forename: Peter M
authors.initials: PM
authors.lastname: Campbell
authors.forename: Steven
authors.initials: S
authors.lastname: Engelen
authors.forename: Yong-Ling
authors.initials: YL
authors.lastname: Ruan
authors.forename: Tony
authors.initials: T
authors.lastname: Arioli
authors.forename: Robert T
authors.initials: RT
authors.lastname: Furbank
mesh_terms: D000595:Amino Acid Sequence; D002473:Cell Wall / Q000201:enzymology*; D032561:Cotton Fiber; D017343:Genes, Plant; D005964:Glucosyltransferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D003368:Gossypium / Q000235:genetics; D007527:Isoenzymes / Q000378:metabolism*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013347:Subcellular Fractions / Q000201:enzymology
chemical_list: D007527:Isoenzymes; D010940:Plant Proteins; D012333:RNA, Messenger; D005964:Glucosyltransferases; C022699:sucrose synthase