Glu-370 in the large subunit influences the substrate binding, allosteric, and heat stability properties of potato ADP-glucose pyrophosphorylase. (November 2016)

• Record Type: Journal Article
• Authors: Seferoglu, Ayse Bengisu; Gul, Seref; Dikbas, Ugur Meric; Baris, Ibrahim; Koper, Kaan; Caliskan, Mahmut; Cevahir, Gul; kavakli, Ibrahim Halil
• Is Part Of: Plant science. Volume 252(2016:Nov.)
• Page Start: 125
• Page End: 132
• Publication Date: 2016-11
• Subjects: AGPase ADP-glucose pyrophosphorylase -- BSA bovine serum albumin -- DTT dithiothreitol -- G1P glucose-1-phosphate -- IPTG isopropyl-β-d-thiogalactopyranoside -- LS large subunit -- 3PGA 3-phosphoglyceric acid -- Pi inorganic phosphate -- SS small subunit -- TBS Tris-buffered saline -- WT wild type; ADP-glucose pyrophosphorylase -- Allosteric regulation -- Protein stability -- Starch biosynthesis; Botany -- Periodicals; Botanique -- Périodiques; 580
• DOI: 10.1016/j.plantsci.2016.07.007
• Languages: English
• ISSNs: 0168-9452

Abstract

Highlights: Glu-370 of the LS AGPase is important for the proper binding of the effectors and substrate. This residue is important for the heat stability of the potato AGPase. 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.