RRC ID 54152
Author Hwang SK, Koper K, Satoh H, Okita TW.
Title Rice Endosperm Starch Phosphorylase (Pho1) Assembles with Disproportionating Enzyme (Dpe1) to Form a Protein Complex That Enhances Synthesis of Malto-oligosaccharides.
Journal J Biol Chem
Abstract Starch synthesis in cereal grain endosperm is dependent on the concerted actions of many enzymes. The starch plastidial phosphorylase (Pho1) plays an important role in the initiation of starch synthesis and in the maturation of starch granule in developing rice seeds. Prior evidence has suggested that the rice enzyme, OsPho1, may have a physical/functional interaction with other starch biosynthetic enzymes. Pulldown experiments showed that OsPho1 as well as OsPho1 devoid of its L80 region, a peptide unique to higher plant phosphorylases, captures disproportionating enzyme (OsDpe1). Interaction of the latter enzyme form with OsDpe1 indicates that the putative regulatory L80 is not responsible for multienzyme assembly. This heterotypic enzyme complex, determined at a molar ratio of 1:1, was validated by reciprocal co-immunoprecipitation studies of native seed proteins and by co-elution chromatographic and co-migration electrophoretic patterns of these enzymes in rice seed extracts. The OsPho1-OsDpe1 complex utilized a broader range of substrates for enhanced synthesis of larger maltooligosaccharides than each individual enzyme and significantly elevated the substrate affinities of OsPho1 at 30 °C. Moreover, the assembly with OsDpe1 enables OsPho1 to utilize products of transglycosylation reactions involving G1 and G3, sugars that it cannot catalyze directly.
Volume 291(38)
Pages 19994-20007
Published 2016-9-16
DOI 10.1074/jbc.M116.735449
PII S0021-9258(20)35977-9
PMID 27502283
PMC PMC5025686
MeSH Endosperm / enzymology* Endosperm / genetics Multienzyme Complexes / genetics Multienzyme Complexes / metabolism* Oligosaccharides / genetics Oligosaccharides / metabolism* Oryza / enzymology* Oryza / genetics Starch Phosphorylase / genetics Starch Phosphorylase / metabolism*
IF 4.238
Times Cited 21
Rice Induced mutation line