TY - JOUR
T1 - Membranes Are Decisive for Maximum Freezing Efficiency of Bacterial Ice Nucleators
AU - Schwidetzky, R.
AU - Sudera, P.
AU - Backes, A. T.
AU - Pöschl, U.
AU - Bonn, M.
AU - Fröhlich-Nowoisky, J.
AU - Meister, Konrad
PY - 2021/11/11
Y1 - 2021/11/11
N2 - Ice-nucleating proteins (INPs) from Pseudomonas syringae are among the most active ice nucleators known, enabling ice formation at temperatures close to the melting point of water. The working mechanisms of INPs remain elusive, but their ice nucleation activity has been proposed to depend on the ability to form large INP aggregates. Here, we provide experimental evidence that INPs alone are not sufficient to achieve maximum freezing efficiency and that intact membranes are critical. Ice nucleation measurements of phospholipids and lipopolysaccharides show that these membrane components are not part of the active nucleation site but rather enable INP assembly. Substantially improved ice nucleation by INP assemblies is observed for deuterated water, indicating stabilization of assemblies by the stronger hydrogen bonds of D 2 O. Together, these results show that the degree of order/disorder and the assembly size are critically important in determining the extent to which bacterial INPs can facilitate ice nucleation.
AB - Ice-nucleating proteins (INPs) from Pseudomonas syringae are among the most active ice nucleators known, enabling ice formation at temperatures close to the melting point of water. The working mechanisms of INPs remain elusive, but their ice nucleation activity has been proposed to depend on the ability to form large INP aggregates. Here, we provide experimental evidence that INPs alone are not sufficient to achieve maximum freezing efficiency and that intact membranes are critical. Ice nucleation measurements of phospholipids and lipopolysaccharides show that these membrane components are not part of the active nucleation site but rather enable INP assembly. Substantially improved ice nucleation by INP assemblies is observed for deuterated water, indicating stabilization of assemblies by the stronger hydrogen bonds of D 2 O. Together, these results show that the degree of order/disorder and the assembly size are critically important in determining the extent to which bacterial INPs can facilitate ice nucleation.
KW - bacteria
KW - freezing
KW - ice
KW - lipids
KW - nucleation
UR - https://doi.org/10.1021/acs.jpclett.1c03118
U2 - 10.1021/acs.jpclett.1c03118
DO - 10.1021/acs.jpclett.1c03118
M3 - Article
C2 - 34723523
VL - 12
JO - The Journal of Physical Chemistry Letters
JF - The Journal of Physical Chemistry Letters
IS - 44
ER -