Michaelis-like complex of mouse ketohexokinase isoform C

Area of Science:

• Biochemistry and Structural Biology
• Metabolic Disease Research

Background:

• Rising incidence of fructose-related diseases like obesity, heart disease, and diabetes over the past 40 years.
• Ketohexokinase (KHK) is a key enzyme in liver fructolysis, catalyzing fructose phosphorylation.
• Understanding KHK's structure-function relationship is vital for developing therapeutic inhibitors.

Purpose of the Study:

• To elucidate the molecular mechanism of Ketohexokinase (KHK) through high-resolution structural analysis.
• To investigate the structure-function relationship of KHK in ligand binding and catalysis.
• To assess the suitability of mouse models for studying KHK-related diseases and therapeutic strategies.

Main Methods:

• High-resolution X-ray crystallography of mouse KHK-C (mKHK-C) at 1.79 Å resolution.
• Determination of the enzyme's structure in a complex with substrate (fructose) and product (ADP).
• Comparison of structural data with unliganded forms to understand conformational changes.

Main Results:

• A high-resolution crystal structure of mKHK-C in a Michaelis-like complex with fructose and ADP was determined.
• Binding of substrates induces a significant conformational change, with a β-sheet domain rotating to form a lid over the active site.
• Mouse and human KHK enzymes exhibit similar kinetic parameters, validating mice as a relevant model for KHK-related disease research.

Conclusions:

• The determined structure provides insight into the catalytic mechanism of KHK-C, highlighting the role of conformational changes.
• The structural and kinetic similarities between mouse and human KHK support the use of mouse models in preclinical studies.
• This molecular understanding is foundational for designing targeted KHK inhibitors to combat fructose-related metabolic diseases.