A phospho-BAD BH3 helix activates glucokinase by a mechanism distinct from that of allosteric activators

Abstract

Glucokinase is a glucose-phosphorylating enzyme that regulates insulin release and hepatic metabolism, and its loss-of-function is implicated in the pathogenesis of diabetes. Glucokinase activators (GKAs) are attractive therapeutics in diabetes, however, clinical data indicate that their benefits can be offset by hypoglycemia due to marked allosteric enhancement of the enzyme’s glucose affinity. We show that a phospho-mimetic of the BCL-2 homology 3 (BH3) alpha-helix derived from human BAD, a glucokinase binding partner, increases the enzyme catalytic rate without dramatically changing glucose affinity, providing a new mechanism for pharmacologic activation of glucokinase. Remarkably, BAD BH3 phospho-mimetic mediates these effects by engaging a novel region near the enzyme’s active site. This interaction increases insulin secretion in human islets and restores the function of naturally-occurring human glucokinase mutants at the active site. Thus, BAD phospho-mimetics may serve as a novel class of GKAs.

The Role of BCL-2 Family Members in Acute Kidney Injury

“…Thus, some forms of diabetes mellitus may result from alterations in bad-mediated glucose metabolism and its detrimental effects on β cell number and proliferation. 58,59 In mitochondria, mcl-1 deletion disrupts cristae architecture and alters normal tubular organelle shape, 60 suggesting an untoward effect on organelle dynamics. Finally, bcl-xl appears to compete with the voltage-dependent anon channel for reduced nicotinamide adenine dinucleotide, a key substrate.…”

“…4 In retrospect, BCL-2 family proteins are perfectly situated between normal metabolism and cell stress and often manifest as a dramatic change in substrate availability to regulate substrate preference and processing. Bad regulates glucokinase, a key component of the glucose sensing machinery, in all mammalian cells (and is tightly linked to insulin secretion in pancreatic β cells 58,59 ). Thus, some forms of diabetes mellitus may result from alterations in bad-mediated glucose metabolism and its detrimental effects on β cell number and proliferation.…”

Macrocyclic α-Helical Peptide Drug Discovery

“…[19][20][21][22][23][24][27][28][29] and 62 for reviews) for the modulation a plethora of intracellular targets (i.e. Bcl2-family, 19,[22][23][24]43,47,48,58,[67][68][69][70][71]76,77,83,92,93,98 p53:MDM2/X, 42,57,65,66,72,79,81,82,87,89,94,95 MAML:Notch, 49 eIF4E, 158 ERa/ERb, 50 IRS1, 84 HIF-1:p300, 56,90 RAS:SOS, 59 Rab-GTPase, 96 b-catenin, 64,78,80 protein kinase-A, 91 RPA, 97 HIV-1 integrase, …”

Regulation of protein–protein interactions using stapled peptides

“…These include cancer targets such as p53, 42 MCL-1 BH3, 43 and PUMA BH3 44 and other therapeutic targets ranging from infectious diseases 45,46 to metabolism. 47,48 Obtaining crystal structures of stapled peptides bound to their targets is not trivial. In fact, there are less than 15 stapled peptide crystal structures available in the literature including an estrogen receptor beta binding stapled peptide 48 and a MCL-1 BH3 stapled peptide 43 ( Figure 3).…”

“…47,48 Obtaining crystal structures of stapled peptides bound to their targets is not trivial. In fact, there are less than 15 stapled peptide crystal structures available in the literature including an estrogen receptor beta binding stapled peptide 48 and a MCL-1 BH3 stapled peptide 43 ( Figure 3). Interestingly, in these solid-state structures, the hydrocarbon staple functionality appears to form hydrophobic interactions with the surface of the target proteins and has been proposed to provide additional binding affinity.…”