Loss of the granule-bound starch synthase protein reshapes the starch proteome and phosphorylation profile in potato tuber
Abstract
Amylose and amylopectin define the structural behavior, gelatinization and retrogradation of starch, while starch phosphorylation modulates its hydration, viscosity, and stability. Granule-bound starch synthase (GBSS) is responsible for amylose biosynthesis, and phosphorylation is catalyzed by the granule associated glucan- and phosphoglucan- water dikinases, (GWD and PWD), respectively. To explore how GBSS influences the association of other starch-binding proteins, we analyzed the starch proteome of two edited tetraploid potato lines using clustered regularly interspaced short palindromic repeats associated with protein 9 technology (CRISPR/Cas9): one lacking GBSS entirely, and one retaining 16% residual expression. Despite reduced total protein content in both lines (by 50% and 35%, respectively), most starch-bound enzymes increased in abundance by 3 to 5-fold, except protein targeting to starch 1 (PTST1), which was absent. This suggests that GBSS loss promotes recruitment of alternative starch-metabolizing enzymes. Elevated levels of granule-bound GWD in the mutants correlated with increased level of C6 phosphate by 1.42-fold, linking GBSS disruption to changes in starch phosphorylation. Moreover, the absence of PTST1 in both lines further supports its role in targeting GBSS to starch granules, providing further insight into the protein–protein interactions governing starch biosynthesis in potato. Overall, the loss of GBSS reorganizes the starch-bound proteome, with most of the other protein quantity being increased, including the dikinases, consequently increasing the granule phosphorylation. These findings highlight how GBSS deficiency reshapes starch composition and proteome organization, with implications for starch structure and functionality.
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BibTeX
@article{helle2026loss,
title = {{Loss of the granule-bound starch synthase protein reshapes the starch proteome and phosphorylation profile in potato tuber}},
author = {Stanislas Helle and François Sevestre and Florian Veillet and Fabrice Bray and Stéphanie Flament and Walaa Derbass and Laura Chauvin and Christian Rolando and Christophe d'Hulst and Jean-Eric Chauvin and Nicolas Szydlowski},
journal = {International Journal of Biological Macromolecules},
year = {2026},
month = oct,
doi = {10.1016/j.ijbiomac.2026.150329},
url = {https://hal.science/hal-05509829v1},
note = {CC BY-NC 4.0},
}
RIS
TY - JOUR
TI - Loss of the granule-bound starch synthase protein reshapes the starch proteome and phosphorylation profile in potato tuber
AU - Stanislas Helle
AU - François Sevestre
AU - Florian Veillet
AU - Fabrice Bray
AU - Stéphanie Flament
AU - Walaa Derbass
AU - Laura Chauvin
AU - Christian Rolando
AU - Christophe d'Hulst
AU - Jean-Eric Chauvin
AU - Nicolas Szydlowski
PY - 2026
DA - 2026/10/13
JO - International Journal of Biological Macromolecules
DO - 10.1016/j.ijbiomac.2026.150329
UR - https://hal.science/hal-05509829v1
AB - Amylose and amylopectin define the structural behavior, gelatinization and retrogradation of starch, while starch phosphorylation modulates its hydration, viscosity, and stability. Granule-bound starch synthase (GBSS) is responsible for amylose biosynthesis, and phosphorylation is catalyzed by the granule associated glucan- and phosphoglucan- water dikinases, (GWD and PWD), respectively. To explore how GBSS influences the association of other starch-binding proteins, we analyzed the starch proteome of two edited tetraploid potato lines using clustered regularly interspaced short palindromic repeats associated with protein 9 technology (CRISPR/Cas9): one lacking GBSS entirely, and one retaining 16% residual expression. Despite reduced total protein content in both lines (by 50% and 35%, respectively), most starch-bound enzymes increased in abundance by 3 to 5-fold, except protein targeting to starch 1 (PTST1), which was absent. This suggests that GBSS loss promotes recruitment of alternative starch-metabolizing enzymes. Elevated levels of granule-bound GWD in the mutants correlated with increased level of C6 phosphate by 1.42-fold, linking GBSS disruption to changes in starch phosphorylation. Moreover, the absence of PTST1 in both lines further supports its role in targeting GBSS to starch granules, providing further insight into the protein–protein interactions governing starch biosynthesis in potato. Overall, the loss of GBSS reorganizes the starch-bound proteome, with most of the other protein quantity being increased, including the dikinases, consequently increasing the granule phosphorylation. These findings highlight how GBSS deficiency reshapes starch composition and proteome organization, with implications for starch structure and functionality.
SN - 0141-8130
ER -