AMP deaminase reaction as a control system of glycolysis in yeast. Activation of phosphofructokinase and pyruvate kinase by the AMP deaminase-ammonia system.

M Yoshino,K Murakami

doi:10.1016/s0021-9258(19)81037-2

Abstract

The role of AMP deaminase (EC 3.5.4.6) reaction in the stimulation of the regulatory enzymes of glycolysis was investigated using permeabilized yeast cells. 1) The addition of polyamine activated AMP deaminase in situ, resulting in the subsequent increase in ammonium production, which can stimulate the activity of 6-phosphofructokinase (EC 2.7.1.11) and pyruvate kinase (EC 2.7.1.40). 2) Zn2+ inhibited AMP deaminase activity, followed by a decrease in ammonium ion concentration which reduced the activity of phosphofructokinase. 3) Polyamine and Zn2+ did not activate or inhibit directly the activity of phosphofructokinase and pyruvate kinase. 4) A simple Michaelis-Menten relationship was observed between the various levels of ammonium ion and of fructose 1,6-biphosphate formed in situ, indicating that phosphofructokinase activity or glycolytic flux was dependent upon the level of ammonium produced through the action of AMP deaminase. 5) The increase in Pi concentration resulted in the decreased magnitude of activation by NH4+ and marked stimulation by Pi itself of phosphofructokinase, and further reduced the production of NH4+ through the inhibition of AMP deaminase, suggesting that phosphofructokinase activity may not be regulated by the level of NH4+ but by Pi concentration under conditions of increased Pi levels. The AMP deaminase-ammonium system shows a regulatory function in glycolysis of yeast cells in the presence of physiological Pi levels, whereas glycolysis may be principally controlled by Pi level under the conditions of elevated Pi concentration. Polyamines may play a part in the stimulation of glycolysis through the elevated level of ammonium ion under the conditions of increased ATP utilization during cell proliferation, and can participate in the catabolic processes as well as anabolic processes through the stimulation of the AMP deaminase-ammonium system.

Highlights

+ From the Department of Biochemistry, Yokohama City University School of Medicine, Yokohama 232, Japan and the Downloaded from http://www.jbc.org/ by guest on October 7, 2020
AMP deaminase may be important in the regulation of adenylate energy nase. 4 ) A simple Michaelis-Menten relationship was charge, adenylate pool size (14-M), and the control of the observed between the variouslevels of ammonium ion purine nucleotide cycle [19]: the importance of the cycle has and of fructose 1,6-biphosphate formed in situ, indicat- been discussed in relation to the controolf glycolysis in some ing thapt hosphofructokinase activityor glycolytic flux tissues.Recently, we presented apermeabilization method was dependent upon the level of ammonium ion pro- which allows the assay of intracellular enzymes within the duced through the action of AMP deaminase
Ammonium ion and P, which increase under conditions of increased ATP utilization, are considered to be responsible for the stimulationof glycolysis [8,9,10,11,12]

Summary

Introduction

The role of AMP deaminase (EC 3.5.4.6) reaction in ulated by phosphate [2,3,4,5,6,7] In keeping with their origin as the the stimulation of the regulatoryenzymes of glycolysis major effectors of the glycolytic pathway, the increasein the was investigated using permeabilized yeast cells. Preliminary evidence was presented tion by Pi itself of phosphofructokinase, and further suggesting that ammonium ion, produced through the actireduced the production of NH4+through the inhibition vation of AMP deaminase, effectively stimulates yeast phosof AMP deaminase, suggesting that phosphofructoki- phofructokinasein the presence of polyamine[21]. Polyaminesmay play a part inthe stimulation of glycolysis throughthe elevated level of ammonium ion under the conditions in the stimulationof glycolysis through the activatioonf AMP deaminase-ammoniumsystemunderthe conditions of increased ATP utilization during cell proliferation

Methods

Results

Conclusion