Glucokinase is a key regulator of glucose homeostasis in the human body. Dysfunction in the regulation and/or activity of glucokinase causes a diverse range of diseases including maturity onset diabetes of the young (MODY) and hyperinsulinemia of infancy (HI). Human glucokinase is a monomeric enzyme that is allosterically regulated by its sugar substrate, D- glucose. This kinetic cooperativity is critical to maintaining proper glucose serum levels in vivo. The goal of this study is to elucidate the mechanistic basis for cooperativity in human glucokinase. The experiments described herein combine a powerful genetic selection system for human glucokinase activity with mechanistic enzymology to provide a kinetic and molecular description of the conformational transitions that give rise to cooperativity.
The specific aims are: (1) To determine the mechanism of activation of hyperinsulinemia-linked glk mutations;(2) To investigate conformational heterogeneity in unliganded glucokinase via chemical quench-flow techniques;(3) To investigate the role of a secondary structural "allosteric switch" in glucokinase cooperativity;(4) To determine whether prolyl cis/trans isomerization is responsible for the slow interconversion of enzyme conformations. Achieving the objectives outlined in this application promises to impact the development of future glucokinase-targeted therapeutics for diabetes and hyperinsulinemia.

Public Health Relevance

In the past five years, human glucokinase has emerged as an attractive therapeutic target for diabetes. Numerous small-molecule activators of glucokinase have been identified and several have been shown to be effective at modulating blood glucose levels in animal models. The successful completion of the aims outlined in this application will provide critical new information about the mechanisms of glucokinase regulation in vivo. This information has the potential to significantly impact future efforts to design glucokinase-targeted therapeutics for diabetes and hyperinsulinemia.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK081358-04
Application #
8267041
Study Section
Macromolecular Structure and Function E Study Section (MSFE)
Program Officer
Sechi, Salvatore
Project Start
2009-06-15
Project End
2014-04-30
Budget Start
2012-05-01
Budget End
2013-04-30
Support Year
4
Fiscal Year
2012
Total Cost
$275,545
Indirect Cost
$79,525
Name
Florida State University
Department
Chemistry
Type
Schools of Arts and Sciences
DUNS #
790877419
City
Tallahassee
State
FL
Country
United States
Zip Code
32306
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Fioramonti, Xavier; Deak, Adam; Deshpande, Srinidhi et al. (2013) Hypothalamic S-nitrosylation contributes to the counter-regulatory response impairment following recurrent hypoglycemia. PLoS One 8:e68709
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Desai, Kevin K; Miller, Brian G (2010) Recruitment of genes and enzymes conferring resistance to the nonnatural toxin bromoacetate. Proc Natl Acad Sci U S A 107:17968-73

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