Investigation of microcystin conformation and binding towards PPP1 by molecular dynamics simulation

Area of Science:

• Environmental toxicology
• Computational chemistry
• Biochemistry

Background:

• Microcystins (MC) are cyanotoxins with 279 variants, posing human health risks through contaminated water and food.
• Current risk assessments often generalize toxicity based on MC-LR, overlooking significant differences among MC congeners.
• Toxicity and pathological outcomes vary considerably between different microcystin variants.

Purpose of the Study:

• To investigate the binding and conformational dynamics of diverse microcystin congeners.
• To apply Molecular Dynamics (MD) simulations for analyzing microcystin-protein interactions.
• To differentiate the behavior of various microcystin structures beyond the commonly assessed MC-LR.

Main Methods:

• Utilized Molecular Dynamics (MD) simulations to analyze four distinct microcystin congeners: MC-LR, MC-LF, [Enantio-Adda5]MC-LF, and [β-D-Asp3,Dhb7]MC-RR.
• Simulated microcystins in both solvent and in complex with ser/thr protein phosphatase 1.
• Analyzed conformational changes and binding affinities of the microcystin congeners.

Main Results:

• Confirmed the stability of ser/thr protein phosphatase 1 across all MD simulations.
• Discovered a previously unknown secondary conformation adopted by the MC-LR backbone in solvent simulations.
• Demonstrated that microcystin congeners adopt different backbone conformations and exhibit varied binding behaviors when simulated in solvent versus when bound to ser/thr protein phosphatase 1.

Conclusions:

• Molecular Dynamics simulations provide valuable insights into the structural variations and binding characteristics of different microcystin congeners.
• Findings challenge the current risk assessment approach, highlighting the need to consider congener-specific toxicity.
• This research aids in a more nuanced understanding of microcystin toxicity and its implications for public health.