Oct 9, 2016

Glu-370 in the large subunit influences the substrate binding, allosteric, and heat stability properties of potato ADP-glucose pyrophosphorylase

Plant Science : an International Journal of Experimental Plant Biology
Ayse Bengisu SeferogluIbrahim Halil Kavakli

Abstract

ADP-glucose pyrophosphorylase (AGPase) is a key allosteric enzyme in plant starch biosynthesis. Plant AGPase is a heterotetrameric enzyme that consists of large (LS) and small subunits (SS), which are encoded by two different genes. In this study, we showed that the conversion of Glu to Gly at position 370 in the LS of AGPase alters the heterotetrameric stability along with the binding properties of substrate and effectors of the enzyme. Kinetic analyses revealed that the affinity of the LS(E370G)SS(WT) AGPase for glucose-1-phosphate is 3-fold less than for wild type (WT) AGPase. Additionally, the LS(E370G)SS(WT) AGPase requires 3-fold more 3-phosphogyceric acid to be activated. Finally, the LS(E370G)SS(WT)AGPase is less heat stable compared with the WT AGPase. Computational analysis of the mutant Gly-370 in the 3D modeled LS AGPase showed that this residue changes charge distribution of the surface and thus affect stability of the LS AGPase and overall heat stability of the heterotetrameric AGPase. In summary, our results show that LS(E370) intricately modulate the heat stability and enzymatic activity of potato the AGPase.

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Mentioned in this Paper

Study
Positioning Attribute
Solocyte
glucose-1-phosphate
Glycerin
Genes
Spectinomycin
Enzymes, antithrombotic
Three-dimensional
Western Blotting

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