Membranes Are Decisive for Maximum Freezing Efficiency of Bacterial Ice Nucleators

R. Schwidetzky, P. Sudera, A. T. Backes, U. Pöschl, M. Bonn, J. Fröhlich-Nowoisky, Konrad Meister

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

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.
Original languageAmerican English
JournalThe Journal of Physical Chemistry Letters
Volume12
Issue number44
DOIs
StatePublished - 11 Nov 2021
Externally publishedYes

Keywords

  • bacteria
  • freezing
  • ice
  • lipids
  • nucleation

EGS Disciplines

  • Chemistry

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