Journal article
Modulation of Allosteric Regulation by E38K and G101N Mutations in the Potato Tuber ADP-glucose Pyrophosphorylase
Bioscience, biotechnology, and biochemistry, Vol.77(9), pp.1854-1859
09/23/2013
Handle:
https://hdl.handle.net/2376/115505
PMID: 24018661
Abstract
The higher plant ADP-glucose (ADPG) pyrophosphorylase (AGPase), composed of two small subunits and two large subunits (LSs), produces ADPG, the sole substrate for starch biosynthesis from α-D-glucose 1-phosphate and ATP. This enzyme controls a key step in starch synthesis as its catalytic activity is activated by 3-phosphoglycerate (3-PGA) and inhibited by orthophosphate (Pi). Previously, two mutations in the LS of potato AGPase (PLS), PLS-E38K and PLS-G101N, were found to increase sensitivity to 3-PGA activation and tolerance to Pi inhibition. In the present study, the double mutated enzyme (PLS-E38K/G101N) was evaluated. In a complementation assay of ADPG synthesis in an Escherichia coli mutant defective in the synthesis of ADPG, expression of PLS-E38K/G101N mediated higher glycogen production than wild-type potato AGPase (PLS-WT) and the single mutant enzymes, PLS-E38K and PLS-G101N, individually. Purified PLS-E38K/G101N showed higher sensitivity to 3-PGA activation and tolerance to Pi inhibition than PLS-E38K or PLS-G101N. Moreover, the enzyme activities of PLS-E38K, PLS-G101N, and PLS-E38K/G101N were more readily stimulated by other major phosphate-ester metabolites, such as fructose 6-phosphate, fructose 2,6-bisphosphate, and ribose 5-phosphate, than was that of PLS-WT. Hence, although the specific enzyme activities of the LS mutants toward 3-PGA were impaired to some extent by the mutations, our results suggest that their enhanced allosteric regulatory properties and the broadened effector selectivity gained by the same mutations not only offset the lowered enzyme catalytic turnover rates but also increase the net performance of potato AGPase in vivo in view of increased glycogen production in bacterial cells.
Metrics
10 Record Views
Details
- Title
- Modulation of Allosteric Regulation by E38K and G101N Mutations in the Potato Tuber ADP-glucose Pyrophosphorylase
- Creators
- Shinji WAKUTA - Research Faculty of Agriculture, Hokkaido UniversityYumi SHIBATA - Research Faculty of Agriculture, Hokkaido UniversityYumiko YOSHIZAKI - Research Faculty of Agriculture, Hokkaido UniversityWataru SABURI - Research Faculty of Agriculture, Hokkaido UniversityShigeki HAMADA - Research Faculty of Agriculture, Hokkaido UniversityHiroyuki ITO - Research Faculty of Agriculture, Hokkaido UniversitySeon-Kap HWANG - Institute of Biological Chemistry, Washington State UniversityThomas W OKITA - Institute of Biological Chemistry, Washington State UniversityHirokazu MATSUI - Research Faculty of Agriculture, Hokkaido University
- Publication Details
- Bioscience, biotechnology, and biochemistry, Vol.77(9), pp.1854-1859
- Academic Unit
- Biological Chemistry, Institute of
- Publisher
- Japan Society for Bioscience, Biotechnology, and Agrochemistry
- Identifiers
- 99900547316501842
- Language
- English
- Resource Type
- Journal article