TY  - JOUR
A1  - Nakamura, Yasunori
A1  - Ono, Masami
A1  - Sawada, Takayuki
A1  - Crofts, Naoko
A1  - Fujita, Naoko
A1  - Steup, Martin
T1  - Characterization of the functional interactions of plastidial starch phosphorylase and starch branching enzymes from rice endosperm during reserve starch biosynthesis
JF  - Plant science : an international journal of experimental plant biology
N2  - Functional interactions of plastidial phosphorylase (Phol) and starch branching enzymes (BEs) from the developing rice endosperm are the focus of this study. In the presence of both Phol and BE, the same branched primer molecule is elongated and further branched almost simultaneously even at very low glucan concentrations present in the purified enzyme preparations. By contrast, in the absence of any BE, glucans are not, to any significant extent, elongated by Phol. Based on our in vitro data, in the developing rice endosperm, Phol appears to be weakly associated with any of the BE isozymes. By using fluorophore-labeled malto-oligosaccharides, we identified maltose as the smallest possible primer for elongation by Phol. Linear dextrins act as carbohydrate substrates for BEs. By functionally interacting with a BE, Phol performs two essential functions during the initiation of starch biosynthesis in the rice endosperm: First, it elongates maltodextrins up to a degree of polymerization of at least 60. Second, by closely interacting with BEs, Phol is able to elongate branched glucans efficiently and thereby synthesizes branched carbohydrates essential for the initiation of amylopectin biosynthesis.
Y1  - 2017
U6  - https://doi.org/10.1016/j.plantsci.2017.09.002
SN  - 0168-9452
VL  - 264
SP  - 83
EP  - 95
PB  - Elsevier
CY  - Clare
ER  -