Formation of callose from sucrose in cotton fiber microsomal membranes

Citation
T. Konishi et al., Formation of callose from sucrose in cotton fiber microsomal membranes, J WOOD SCI, 47(5), 2001, pp. 331-335
Citations number
18
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Material Science & Engineering
Journal title
JOURNAL OF WOOD SCIENCE
ISSN journal
1435-0211 → ACNP
Volume
47
Issue
5
Year of publication
2001
Pages
331 - 335
Database
ISI
SICI code
1435-0211(2001)47:5<331:FOCFSI>2.0.ZU;2-J
Abstract
Callose is formed from exogenous sucrose by cotton fiber microsomal membran es that contain both sucrose synthase and callose synthase activity. Althou gh the coupled reaction between sucrose and callose synthases occurs predom inantly to channel glucose from sucrose-derived uridine diphosphate (UDP)-g lucose into callose in the membranes, there is no difference in the UDP-glu cose-forming/sucrose-forming activity ratios between the soluble and membra ne-bound forms of sucrose synthase. The consumption of UDP-glucose from suc rose into callose probably leads to UDP-glucose formation rather than sucro se formation despite the lower affinity of sucrose synthase for sucrose tha n for UDP-glucose. Callose formation is markedly stimulated by the addition of either recombinant Glu(11) (S11E) or in vitro phosphorylated Ser(11) mu ng, bean sucrose synthase but not by the wild-type nonphosphorylated Ser(11 ) enzyme. We propose that a negative charge (by phosphorylation or mutagene sis) at Ser(11) in sucrose synthase causes the enzyme to promote a coupled callose-forming reaction.