Dynamic Preference for NADP/H Cofactor Binding/Release in E. coli YqhD Oxidoreductase

Area of Science:

• Biocatalysis and Enzyme Engineering
• Computational Biochemistry
• Molecular Dynamics Simulations

Background:

• YqhD from *E. coli* is an alcohol/aldehyde oxidoreductase with potential for producing bio-renewable fuels and chemicals.
• Understanding enzyme conformational dynamics is crucial for optimizing biocatalyst performance.
• Cofactor binding significantly influences enzyme activity and substrate specificity.

Purpose of the Study:

• To perform the first computational solution-phase structure-dynamics analysis of YqhD.
• To investigate the impact of oxidized (NADP) and reduced (NADPH) cofactor binding on YqhD's conformational dynamics.
• To elucidate the mechanisms underlying cofactor binding/release and their effect on enzyme activity.

Main Methods:

• Utilized molecular dynamics (MD) simulations to analyze YqhD structure and dynamics in solution.
• Focused on the influence of NADP+ and NADPH cofactor binding states.
• Correlated simulation findings with existing enzyme kinetics and structural data.

Main Results:

• Cofactor oxidation state primarily affects the interdomain cleft region dynamics, crucial for cofactor binding and release.
• NADPH-bound YqhD exhibits a narrower interdomain space, indicating more rigid cofactor binding and enhanced hydrogen bonding.
• NADP-bound YqhD shows fluctuations between open and closed conformations, with slower opening/closing dynamics for NADPH-bound states.

Conclusions:

• The open conformation favored by NADP+ facilitates easier cofactor release.
• Increased sampling of the closed conformation upon NADPH binding enhances cofactor affinity and aldehyde reductase activity.
• These dynamics provide insights into optimizing YqhD for bio-production applications.