Dimer interface rearrangement of the 6‐phosphofructo‐2‐kinase/fructose 2,6‐bisphosphatase rat liver isoenzyme by cAMP‐dependent Ser‐32 phosphorylation

Langer, Sara; Okar, David A.; Schultz, Julia; Lenzen, Sigurd; Baltrusch, Simone

doi:10.1016/j.febslet.2012.03.066

Cited by 5 publications

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References 27 publications

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“…Plasmids and cDNA All experiments were performed with the beta cell isoform of human GK. The GK-CHI mutants V455L (GK-L455) and V455M (GK-M455) [12] as well as the MODY2 mutant V455E (GK-E455) [14,15,21] were introduced into the vector pDendra2-C-GK wild-type, which is based on the mammalian expression vector pDendra2-C (Evrogen, Moscow, Russia) and encodes an N-terminal fusion of the fluorescent protein Dendra2 to GK [22]. Site-directed mutagenesis was performed with the QuikChange II Site-Directed Mutagenesis Kit (Agilent, Santa Clara, CA, USA) according to the manufacturer's instructions.…”

Section: Methodsmentioning

confidence: 99%

The novel GCK variant p.Val455Leu associated with hyperinsulinism is susceptible to allosteric activation and is conducive to weight gain and the development of diabetes

et al. 2021

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Aims/hypothesis The mammalian enzyme glucokinase (GK), expressed predominantly in liver and pancreas, plays an essential role in carbohydrate metabolism. Monogenic GK disorders emphasise the role of GK in determining the blood glucose set point. Methods A family with congenital hyperinsulinism (CHI) was examined for GCK gene variants by Sanger sequencing. A combined approach, involving kinetic analysis (also using GK activators and inhibitors), intracellular translocation assays, insulin secretion measurements and structural modelling, was used to investigate the novel variant compared with known variants. Results We report on the novel gain-of-function GCK variant p.Val455Leu (V455L), inherited as an autosomal dominant trait in a German family with CHI and concomitant obesity (fasting blood glucose 2.1 mmol/l, BMI 45.0 kg/m2, HOMA-IR 1.5 in an adult female family member); one male family member developed type 2 diabetes until age 35 years (with fasting glucose 2.8–3.7 mmol/l, BMI 38.9 kg/m2, HOMA-IR 4.6). Kinetic characterisation of the V455L variant revealed a significant increase in glucose affinity (glucose concentration at which reaction rate is half its maximum rate [S0.5]: mutant 2.4 ± 0.3 mmol/l vs wild-type 7.6 ± 1.0 mmol/l), accompanied by a distinct additive susceptibility to both the endogenous activator fructose 2,6-bisphosphatase and the synthetic allosteric activator RO-28-1675. The effect of RO-28-1675 was more pronounced when compared with the previously known GK variants V455M and V455E. Binding to the inhibitor glucokinase regulatory protein was unimpaired for V455L and V455E but was reduced for V455M, whereas mannoheptulose inhibited all GK variants and the wild-type enzyme. Structural analyses suggested a role for residue 455 in rearrangements between the inactive and active conformations of GK and also in allosteric activation. Comparison with V455M and V455E and an overview of activating GK variants provided a context for the novel sequence aberration in terms of altered GK enzyme characteristics caused by single amino acid changes. Conclusion/interpretation We provide new knowledge on the structure–function relationship of GK, with special emphasis on enzyme activation, potentially yielding fresh strategic insights into breaking the vicious circle of fluctuating blood glucose levels and the attendant risk of long-lasting metabolic changes in both CHI and type 2 diabetes. Graphical abstract

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