Sucrose synthase activity in the sus1/sus2/sus3/sus4 Arabidopsis mutant is sufficient to support normal cellulose and starch production
Fecha
2011Autor
Versión
Acceso abierto / Sarbide irekia
Tipo
Artículo / Artikulua
Versión
Versión publicada / Argitaratu den bertsioa
Impacto
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10.1073/pnas.1117099109
Resumen
Sucrose synthase (SUS) catalyzes the reversible conversion of
sucrose and a nucleoside diphosphate into the corresponding
nucleoside diphosphate-glucose and fructose. In Arabidopsis,
a multigene family encodes six SUS (SUS1-6) isoforms. The involvement
of SUS in the synthesis of UDP-glucose and ADP-glucose
linked to Arabidopsis cellulose and starch biosynthesis, respectively,
has been questioned ...
[++]
Sucrose synthase (SUS) catalyzes the reversible conversion of
sucrose and a nucleoside diphosphate into the corresponding
nucleoside diphosphate-glucose and fructose. In Arabidopsis,
a multigene family encodes six SUS (SUS1-6) isoforms. The involvement
of SUS in the synthesis of UDP-glucose and ADP-glucose
linked to Arabidopsis cellulose and starch biosynthesis, respectively,
has been questioned by Barratt et al. [(2009) Proc Natl Acad
Sci USA 106:13124–13129], who showed that (i) SUS activity in
wild type (WT) leaves is too low to account for normal rate of
starch accumulation in Arabidopsis, and (ii) different organs of
the sus1/sus2/sus3/sus4 SUS mutant impaired in SUS activity accumulate
WT levels of ADP-glucose, UDP-glucose, cellulose and
starch. However, these authors assayed SUS activity under unfavorable
pH conditions for the reaction. By using favorable pH conditions
for assaying SUS activity, in this work we show that SUS
activity in the cleavage direction is sufficient to support normal
rate of starch accumulation in WT leaves. We also demonstrate
that sus1/sus2/sus3/sus4 leaves display WT SUS5 and SUS6 expression
levels, whereas leaves of the sus5/sus6 mutant display WT
SUS1–4 expression levels. Furthermore, we show that SUS activity
in leaves and stems of the sus1/sus2/sus3/sus4 and sus5/sus6 plants
is ~85% of that of WT leaves, which can support normal cellulose
and starch biosynthesis. The overall data disprove Barratt et al.
(2009) claims, and are consistent with the possible involvement
of SUS in cellulose and starch biosynthesis in Arabidopsis. [--]
Materias
Carbohydrate metabolism,
Sink strength
Editor
National Academy of Sciences
Publicado en
PNAS, January 3, 2012 109 (1) 321-326
Departamento
Universidad Pública de Navarra/Nafarroako Unibertsitate Publikoa. IdAB. Instituto de Agrobiotecnología / Agrobioteknologiako Institutua
Versión del editor
Entidades Financiadoras
This research was partially supported by the Grant BIO2010-18239 from the
Comisión Interministerial de Ciencia y Tecnología and Fondo Europeo de
Desarrollo Regional (Spain), and by Iden Biotechnology S.L. G.A. acknowledges
a fellowship from the Public University of Navarra.