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

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Abstract

Antifreeze proteins (AFP) 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-Thomspon 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-Thompson law.

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Michael J Kuiper

Victorian Life Sciences Computation Initiative, The University of Melbourne, Carlton, Australia

For correspondence
mkuiper@unimelb.edu.au

Competing interests
The authors declare that no competing interests exist.
Craig J Morton

ACRF Rational Drug Discovery Centre, St Vincent's Institute of Medical Research, Fitzroy, Australia

Competing interests
The authors declare that no competing interests exist.
Sneha E Abraham

School of Chemistry, The University of Melbourne, Melbourne, Australia

Competing interests
The authors declare that no competing interests exist.
Angus Gray-Weale

School of Chemistry, The University of Melbourne, Melbourne, Australia

Competing interests
The authors declare that no competing interests exist.

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