Crystallization and structural characterization of the Lyver-type glutaminase (LGA)

Abstract

Discovered by Hans Krebs nearly a century ago, the mitochondrial mammalian glutaminases proved highly complex enzymes in terms of primary sequence, leading to speculation about possible additional functions inside cells beyond their catalytic activity over the amino acid glutamine. Mammalian contain two distinct but structurally related genes coding for at least three different isoenzymes referred to as Kidney-type glutaminase (or KGA), Glutaminase C (or GAC) and Liver-type glutaminase (or LGA). One of the most important features of these proteins is the altered pattern of expression in tumor tissues. Recent results obtained in our laboratory, who has studied in depth the isoforms KGA and GAC, show that LGA has distinct catalytic properties when compared with others, including response to the activator inorganic phosphate. Furthermore, in cellular models, LGA expression is controlled by the tumor suppressor p53, and its presence has been described as antagonistic to supply the metabolic needs of tumors. Its primary sequence suggests the possibility that LGA can interact with other proteins in different organelles besides mitochondria, even participating in a direct way in the regulation of gene expression. Within this context, and according to both the current line of research of our lab and the project of the candidate and current MSc student Igor Monteze Ferreira, the proposed project aims to determine the crystallographic structure of LGA, in collaboration with the group of Metabolism and Organelle Biogenesis of the Structural Genomics Consortium, at the University of Oxford, UK. The SGC is a leading global consortium focused on structural biology of human proteins with an interest in health. The internship will be supervised by Dr. Wyatt Yue, who is responsible for the group, due to its extensive experience with structural studies of metabolic protein. In case of success in obtaining LGA crystals, the student will have access to the beamlines dedicated to macromolecular crystallography at Diamond Light Source, located in the vicinity of Oxford. (AU)