Journal of Proteomics & Bioinformatics
Open Access

Discovery of a GTP sensor using a structural reverse genetic approach

6^th International Conference on Structural Biology

August 22-23, 2016 New Orleans, USA

Toshiya Senda

High Energy Accelerator Research Organization (KEK), Japan

Scientific Tracks Abstracts: J Proteomics Bioinform

Abstract :

GTP is an energy molecule in the cell and required in protein synthesis. Reduction of GTP concentration results in slow cell growth; inversely, rapidly growing cells have elevated GTP concentration. Because of its vital roles in cell growth, GTP concentration should be monitored and homeostatically regulated in the cell. However, a sensing mechanism of cellular GTP concentration remains elusive. Here, we show that a lipid kinase, PI5P4K�², serves as a GTP sensor and GTP concentration functions as a metabolic cue via PI5P4K�². Our proteomics and biochemical study revealed that PI5P4K�² binds GTP and its enzyme activity is significantly higher with GTP than with ATP; PI5P4K�² mainly utilizes GTP for phosphorylation of PI5P. Furthermore, the kinetic characters of PI5P4K�² are suitable to detect the change of cellular GTP concentration. These biochemical characteristics suggested that PI5P4K�² is a GTP sensor in the cell. However, since PI5P4K�² can utilize not only GTP but also ATP for the enzyme reaction in the cell, a simple knockout/down experiment is insufficient to analyze the biological function of the GTP-sensing activity of PI5P4K�². We therefore took a structural reverse genetic approach. First, we determined crystal structures of PI5P4K�²-ATP/GTP complexes and used the crystal structures to prepare a PI5P4K�² mutant that lacks GTP-sensing activity without changing ATP-dependent activity. We then preformed biological and metabolomic analyses with the PI5P4K�² mutant, revealing that PI5P4K�² serves as a GTP-sensor. The GTP-sensing activity of PI5P4K�² is critical for metabolic adaptation and tumorigenesis.

Biography :

Toshiya Senda has completed his PhD from Nagaoka University of Technology, Niigata, Japan in 1995. He was a Research Associate in Nagaoka University of Technology (1995-2001) and a Senior Researcher in Institute of Advanced Industrial Science and Technology (2001-2012). Currently, he is the Director/Professor of Structural Biology Research Center of High Energy Accelerator Research Organization in Japan. He was awarded the CrSJ (Crystallographic Society of Japan) Award in 2014.

Email: toshiya.senda@kek.jp