Conformational transition pathway in the allosteric process of human glucokinase

Abstract

Glucokinase (GK) is an important enzyme for regulating blood glucose levels and a potentially attractive target for diabetes of the young type 2 and persistent hyperinsulinemic hypoglycemia of infancy. To characterize the conformational transition of GK from the closed state to the superopen state, a series of conventional molecular dynamics (MD) and target MD (TMD) simulations were performed on both the wild-type enzyme and its mutants. Two 10-ns conventional MD simulations showed that, although the allosteric site of GK is Ϸ20 Å away from the active site, the activator is able to enhance the activity of the enzyme through conformational restriction. Fourteen TMD simulations on GK and five of its mutants revealed a reliably conformational transition pathway. The overall conformational transition includes three stages, and three likely stable intermediate states were identified by free energy scanning for the snapshots throughout the pathway. The conformational transition feature revealed by our TMD simulations rationalized several important mutagenesis and kinetic data. Remarkably, the TMD simulations predicted that Y61S, I159A, A201R, V203E, and V452S mutations, which have not been investigated so far, may facilitate the opening process of GK. These predictions also have been verified by mutagenesis and kinetic analyses in this study. These observations are beneficial to understanding the mechanism of GK regulation and designing the compounds for treating metabolic diseases. molecular dynamics ͉ mutagenesis

Activating glucokinase (GCK) mutations as a cause of medically responsive congenital hyperinsulinism: prevalence in children and characterisation of a novel GCK mutation.

“…This paradox may be explained by the inability to bind regulatory proteins such as GCK regulatory protein GKRP and/or unidentified endogenous GCK activators (32). The allosteric area is involved in transforming GCK from the closed (active) to the super-open (nonactive) state of the enzyme, involving three intermediate stages (30,33). Proposed natural ligands and activating mutations slow down the conformational changes between the intermediate stages from the closed to the super -open stage.…”

Human 60-kDa Lysophospholipase Contains an N-terminal l-Asparaginase Domain That Is Allosterically Regulated by l-Asparagine

“…In contrast, hASNase1, which shows nonMichaelis-Menten kinetics similar to its E. coli homolog, is monomeric under the conditions of activity measurements. In fact, a number of monomeric enzymes exhibiting allosteric behavior have been reported of which the most thoroughly characterized is human glucokinase (57,58). However, glucokinase (also called hexokinase IV), unlike L-asparaginase, is a twosubstrate (ATP plus glucose) enzyme and displays a moderate degree of allostery (59).…”

Identification of 9- cis -retinoic acid as a pancreas-specific autacoid that attenuates glucose-stimulated insulin secretion

“…Glucose uptake by the pancreas rapidly affects both Glut2 and GK activities through posttranslational mechanisms (22,23). Although GK activity limits the rate of glucose uptake by the β-cell, Glut2 contributes more than passive glucose transport by signaling glucose concentrations: phosphorylation decreases both the transport and signaling functions of Glut2 (22,24).…”