Exploring the Effects of Subfreezing Temperature and Salt Concentration on Ice Growth Inhibition of Antarctic Gram-Negative Bacterium Marinomonas Primoryensis Using Coarse-Grained Simulation

Abstract

The aim of this work is to study the freezing process of water molecules surrounding Antarctic Gram-negative bacterium Marinomonas primoryensis antifreeze protein (MpAFP) and the MpAFP interactions to the surface of ice crystals under various marine environments (at different NaCl concentrations of 0.3, 0.6, and 0.8 mol/l). Our result indicates that activating temperature region of MpAFPs reduced as NaCl concentration increased. Specifically, MpAFP was activated and functioned at 0.6 mol/l with temperatures equal or larger 278 K, and at 0.8 mol/l with temperatures equal or larger 270 K. Additionally, MpAFP was inhibited by ice crystal network from 268 to 274 K and solid-liquid hybrid from 276 to 282 K at 0.3 mol/l concentration. Our results shed lights on structural dynamics of MpAFP among different marine environments.

Investigation of changes in structure and thermodynamic of spruce budworm antifreeze protein under subfreezing temperature

“…The collective motions, fluctuation, and relaxation dynamics of liquid water will be reduced and completely inhibited in order to form ice crystal (crystallization or recrystallization process). This is similar to the hydrophobic interaction between AFPs and the environment was increased when bulk water surrounding AFPs transferred from liquid form to ice crystal at low temperatures33031 or AFPs transferred from liquid water region to CHX region. Therefore, the characteristics of hydrophobic and hydrophilic interactions at ice-binding and non-ice-binding sites of sbAFP in environment containing water and CHX molecules were used to investigate sbAFP’s activity at low temperatures.…”

“…In previous publications, the experimental methods (X-Ray diffraction, Neutron diffraction or solution NMR) and molecular dynamics simulations (atomistic or coarse grained models) are used to study the freezing process of water molecules surrounding AFPs at low temperatures32430313946. The aqueous solution is observed to be frozen at extremely low temperature, formed the ice crystal network under the vaguely hexagonal shape due to the special bond angles within the water molecules as it forms a solid crystal lattice, and fully represented the characteristic of hydrophobic interaction363.…”

“…Moreover, previous studies also showed that ice growth is kinetically inhibited by AFPs covering the water accessible surfaces of ice252627. AFPs are particularly sensitive to cooling condition as their molecular adaptation to ice crystal is induced through the gradual formation of ice cascade surrounding AFP which can also be interpreted as AFPs can be inactivated if subfreezing temperature suddenly drops28293031.…”