TY  - JOUR
A1  - Mahlow, Sebastian
A1  - Hejazi, Mahdi
A1  - Kuhnert, Franziska
A1  - Garz, Andreas
A1  - Brust, Henrike
A1  - Baumann, Otto
A1  - Fettke, Jörg
T1  - Phosphorylation of transitory starch by -glucan, water dikinase during starch turnover affects the surface properties and morphology of starch granules
T2  - New phytologist : international journal of plant science
N2  - Glucan, water dikinase (GWD) is a key enzyme of starch metabolism but the physico-chemical properties of starches isolated from GWD-deficient plants and their implications for starch metabolism have so far not been described. Transgenic Arabidopsis thaliana plants with reduced or no GWD activity were used to investigate the properties of starch granules. In addition, using various in vitro assays, the action of recombinant GWD, -amylase, isoamylase and starch synthase 1 on the surface of native starch granules was analysed. The internal structure of granules isolated from GWD mutant plants is unaffected, as thermal stability, allomorph, chain length distribution and density of starch granules were similar to wild-type. However, short glucan chain residues located at the granule surface dominate in starches of transgenic plants and impede GWD activity. A similarly reduced rate of phosphorylation by GWD was also observed in potato tuber starch fractions that differ in the proportion of accessible glucan chain residues at the granule surface. A model is proposed to explain the characteristic morphology of starch granules observed in GWD transgenic plants. The model postulates that the occupancy rate of single glucan chains at the granule surface limits accessibility to starch-related enzymes.
KW  - Arabidopsis thaliana
KW  - glucan
KW  - water dikinase (GWD)
KW  - sex1-8
KW  - starch granule surface
KW  - starch phosphorylation
Y1  - 2014
UR  - https://publishup.uni-potsdam.de/frontdoor/index/index/docId/37756
SN  - 0028-646X
SN  - 1469-8137
VL  - 203
IS  - 2
SP  - 495
EP  - 507
PB  - Wiley-Blackwell
CY  - Hoboken
ER  -