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Title: The Crystal Structure of Toxoplasma gondii Pyruvate Kinase 1

Abstract

Pyruvate kinase (PK), which catalyzes the final step in glycolysis converting phosphoenolpyruvate to pyruvate, is a central metabolic regulator in most organisms. Consequently PK represents an attractive therapeutic target in cancer and human pathogens, like Apicomplexans. The phylum Aplicomplexa, a group of exclusively parasitic organisms, includes the genera Plasmodium, Cryptosporidium and Toxoplasma, the etiological agents of malaria, cryptosporidiosis and toxoplasmosis respectively. Toxoplasma gondii infection causes a mild illness and is a very common infection affecting nearly one third of the world's population. We have determined the crystal structure of the PK1 enzyme from T. gondii, with the B domain in the open and closed conformations. We have also characterized its enzymatic activity and confirmed glucose-6-phosphate as its allosteric activator. This is the first description of a PK enzyme in a closed inactive conformation without any bound substrate. Comparison of the two tetrameric TgPK1 structures indicates a reorientation of the monomers with a concomitant change in the buried surface among adjacent monomers. The change in the buried surface was associated with significant B domain movements in one of the interacting monomers. We hypothesize that a loop in the interface between the A and B domains plays an important role linking themore » position of the B domain to the buried surface among monomers through two {alpha}-helices. The proposed model links the catalytic cycle of the enzyme with its domain movements and highlights the contribution of the interface between adjacent subunits. In addition, an unusual ordered conformation was observed in one of the allosteric binding domains and it is related to a specific apicomplexan insertion. The sequence and structural particularity would explain the atypical activation by a mono-phosphorylated sugar. The sum of peculiarities raises this enzyme as an emerging target for drug discovery.« less

Authors:
; ; ; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
Sponsoring Org.:
DOE - OFFICE OF SCIENCE
OSTI Identifier:
1020166
Report Number(s):
BNL-96016-2011-JA
TRN: US201116%%146
DOE Contract Number:  
DE-AC02-98CH10886
Resource Type:
Journal Article
Journal Name:
PLoS One
Additional Journal Information:
Journal Volume: 5; Journal Issue: 9
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; 99 GENERAL AND MISCELLANEOUS//MATHEMATICS, COMPUTING, AND INFORMATION SCIENCE; CRYSTAL STRUCTURE; ENZYMES; GLYCOLYSIS; MALARIA; MONOMERS; NEOPLASMS; PATHOGENS; PHOSPHOENOLPYRUVATE; PHOSPHOTRANSFERASES; PLASMODIUM; SACCHAROSE; TARGETS; national synchrotron light source

Citation Formats

Bakszt, R, Wernimont, A, Allali-Hassani, A, Mok, M, Hills, T, Hui, R, and Pizarro, J. The Crystal Structure of Toxoplasma gondii Pyruvate Kinase 1. United States: N. p., 2010. Web. doi:10.1371/journal.pone.0012736.
Bakszt, R, Wernimont, A, Allali-Hassani, A, Mok, M, Hills, T, Hui, R, & Pizarro, J. The Crystal Structure of Toxoplasma gondii Pyruvate Kinase 1. United States. https://doi.org/10.1371/journal.pone.0012736
Bakszt, R, Wernimont, A, Allali-Hassani, A, Mok, M, Hills, T, Hui, R, and Pizarro, J. 2010. "The Crystal Structure of Toxoplasma gondii Pyruvate Kinase 1". United States. https://doi.org/10.1371/journal.pone.0012736.
@article{osti_1020166,
title = {The Crystal Structure of Toxoplasma gondii Pyruvate Kinase 1},
author = {Bakszt, R and Wernimont, A and Allali-Hassani, A and Mok, M and Hills, T and Hui, R and Pizarro, J},
abstractNote = {Pyruvate kinase (PK), which catalyzes the final step in glycolysis converting phosphoenolpyruvate to pyruvate, is a central metabolic regulator in most organisms. Consequently PK represents an attractive therapeutic target in cancer and human pathogens, like Apicomplexans. The phylum Aplicomplexa, a group of exclusively parasitic organisms, includes the genera Plasmodium, Cryptosporidium and Toxoplasma, the etiological agents of malaria, cryptosporidiosis and toxoplasmosis respectively. Toxoplasma gondii infection causes a mild illness and is a very common infection affecting nearly one third of the world's population. We have determined the crystal structure of the PK1 enzyme from T. gondii, with the B domain in the open and closed conformations. We have also characterized its enzymatic activity and confirmed glucose-6-phosphate as its allosteric activator. This is the first description of a PK enzyme in a closed inactive conformation without any bound substrate. Comparison of the two tetrameric TgPK1 structures indicates a reorientation of the monomers with a concomitant change in the buried surface among adjacent monomers. The change in the buried surface was associated with significant B domain movements in one of the interacting monomers. We hypothesize that a loop in the interface between the A and B domains plays an important role linking the position of the B domain to the buried surface among monomers through two {alpha}-helices. The proposed model links the catalytic cycle of the enzyme with its domain movements and highlights the contribution of the interface between adjacent subunits. In addition, an unusual ordered conformation was observed in one of the allosteric binding domains and it is related to a specific apicomplexan insertion. The sequence and structural particularity would explain the atypical activation by a mono-phosphorylated sugar. The sum of peculiarities raises this enzyme as an emerging target for drug discovery.},
doi = {10.1371/journal.pone.0012736},
url = {https://www.osti.gov/biblio/1020166}, journal = {PLoS One},
number = 9,
volume = 5,
place = {United States},
year = {Fri Jan 01 00:00:00 EST 2010},
month = {Fri Jan 01 00:00:00 EST 2010}
}