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Effects of Ice Nucleation Protein Repeat Number and Oligomerization Level on Ice Nucleation Activity

Ling, M. L.; Wex, H.; Grawe, S.; Jakobsson, J. LU ; Löndahl, J. LU ; Hartmann, S.; Finster, K.; Boesen, T. and Šantl-Temkiv, T. LU (2018) In Journal of Geophysical Research: Atmospheres
Abstract

Ice nucleation active bacteria have attracted particular attention due to their unique ability to produce specific ice nucleation proteins (INpros), which are the most efficient ice nuclei known as they induce nucleation at temperatures close to 0°C. Our model bacterium Pseudomonas syringae strain R10.79 produced INpros containing 67 tandem repeats, forming the proposed ice-binding surface. To understand the role of the INpro repeats as well as the role of intermolecular interactions between INpros for their ice nucleation behavior, we produced a truncated version of the protein with only 16 tandem repeats (INpro16R). The purified INpro16R produced oligomers of varying sizes. Immersion freezing ice nucleation... (More)

Ice nucleation active bacteria have attracted particular attention due to their unique ability to produce specific ice nucleation proteins (INpros), which are the most efficient ice nuclei known as they induce nucleation at temperatures close to 0°C. Our model bacterium Pseudomonas syringae strain R10.79 produced INpros containing 67 tandem repeats, forming the proposed ice-binding surface. To understand the role of the INpro repeats as well as the role of intermolecular interactions between INpros for their ice nucleation behavior, we produced a truncated version of the protein with only 16 tandem repeats (INpro16R). The purified INpro16R produced oligomers of varying sizes. Immersion freezing ice nucleation behavior of purified INpro16R was characterized by droplet-freezing assays and in the Leipzig Aerosol Cloud Interaction Simulator. Predominant INpro16R oligomers introduced into Leipzig Aerosol Cloud Interaction Simulator as single particles with diameters of 50 nm or 70 nm were ice nucleation active at temperatures of -26°C and -24°C, respectively. These are much lower temperatures compared to that of intact INpros (-12°C). The data clearly indicated that the number of repeats determines the ice nucleation temperature. In addition, ice nucleation between -9°C and -10°C, comparable to the activity of intact INpro, was caused by higher-order INpro16R oligomers. This supported previous observations that INpro oligomerization increases the ice-binding surface, thereby affecting ice nucleation activity. In conclusion, both repeat number and oligomerization contribute in a seemingly independent manner to the nucleation mechanism of INpros.

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author
organization
publishing date
type
Contribution to journal
publication status
epub
subject
keywords
Bioaerosols, Precipitation
in
Journal of Geophysical Research: Atmospheres
publisher
American Geophysical Union
external identifiers
  • scopus:85041826197
ISSN
2169-897X
DOI
10.1002/2017JD027307
language
English
LU publication?
yes
id
4ba1d97b-2bc5-46d8-8abd-d8b0919c2a2d
date added to LUP
2018-02-22 07:33:14
date last changed
2018-09-16 04:53:25
@article{4ba1d97b-2bc5-46d8-8abd-d8b0919c2a2d,
  abstract     = {<p>Ice nucleation active bacteria have attracted particular attention due to their unique ability to produce specific ice nucleation proteins (INpros), which are the most efficient ice nuclei known as they induce nucleation at temperatures close to 0°C. Our model bacterium Pseudomonas syringae strain R10.79 produced INpros containing 67 tandem repeats, forming the proposed ice-binding surface. To understand the role of the INpro repeats as well as the role of intermolecular interactions between INpros for their ice nucleation behavior, we produced a truncated version of the protein with only 16 tandem repeats (INpro<sub>16R</sub>). The purified INpro<sub>16R</sub> produced oligomers of varying sizes. Immersion freezing ice nucleation behavior of purified INpro<sub>16R</sub> was characterized by droplet-freezing assays and in the Leipzig Aerosol Cloud Interaction Simulator. Predominant INpro<sub>16R</sub> oligomers introduced into Leipzig Aerosol Cloud Interaction Simulator as single particles with diameters of 50 nm or 70 nm were ice nucleation active at temperatures of -26°C and -24°C, respectively. These are much lower temperatures compared to that of intact INpros (-12°C). The data clearly indicated that the number of repeats determines the ice nucleation temperature. In addition, ice nucleation between -9°C and -10°C, comparable to the activity of intact INpro, was caused by higher-order INpro<sub>16R</sub> oligomers. This supported previous observations that INpro oligomerization increases the ice-binding surface, thereby affecting ice nucleation activity. In conclusion, both repeat number and oligomerization contribute in a seemingly independent manner to the nucleation mechanism of INpros.</p>},
  author       = {Ling, M. L. and Wex, H. and Grawe, S. and Jakobsson, J. and Löndahl, J. and Hartmann, S. and Finster, K. and Boesen, T. and Šantl-Temkiv, T.},
  issn         = {2169-897X},
  keyword      = {Bioaerosols,Precipitation},
  language     = {eng},
  month        = {02},
  publisher    = {American Geophysical Union},
  series       = {Journal of Geophysical Research: Atmospheres},
  title        = {Effects of Ice Nucleation Protein Repeat Number and Oligomerization Level on Ice Nucleation Activity},
  url          = {http://dx.doi.org/10.1002/2017JD027307},
  year         = {2018},
}