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The biological function of an insect antifreeze protein simulated by molecular dynamics

2015; eLife Sciences Publications Ltd; Volume: 4; Linguagem: Inglês

10.7554/elife.05142

2050-084X

Michael J. Kuiper, Craig J. Morton, Sneha Elizabeth Abraham, Angus Gray–Weale,

Insect and Arachnid Ecology and Behavior

Antifreeze proteins (AFPs) protect certain cold-adapted organisms from freezing to death by selectively adsorbing to internal ice crystals and inhibiting ice propagation. The molecular details of AFP adsorption-inhibition is uncertain but is proposed to involve the Gibbs–Thomson effect. Here we show by using unbiased molecular dynamics simulations a protein structure-function mechanism for the spruce budworm Choristoneura fumiferana AFP, including stereo-specific binding and consequential melting and freezing inhibition. The protein binds indirectly to the prism ice face through a linear array of ordered water molecules that are structurally distinct from the ice. Mutation of the ice binding surface disrupts water-ordering and abolishes activity. The adsorption is virtually irreversible, and we confirm the ice growth inhibition is consistent with the Gibbs–Thomson law.