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The physical state of water in bacterial spores.

Persson Sunde, Erik LU ; Setlow, Peter; Hederstedt, Lars LU and Halle, Bertil LU (2009) In Proceedings of the National Academy of Sciences 106(46). p.19334-19339
Abstract
The bacterial spore, the hardiest known life form, can survive in a metabolically dormant state for many years and can withstand high temperatures, radiation, and toxic chemicals. The molecular basis of spore dormancy and resistance is not understood, but the physical state of water in the different spore compartments is thought to play a key role. To characterize this water in situ, we recorded the water 2H and 17O spin relaxation rates in D2O-exchanged Bacillus subtilis spores over a wide frequency range. The data indicate high water mobility throughout the spore, comparable with binary protein–water systems at similar hydration levels. Even in the dense core, the average water rotational correlation time is only 50 ps. Spore dormancy... (More)
The bacterial spore, the hardiest known life form, can survive in a metabolically dormant state for many years and can withstand high temperatures, radiation, and toxic chemicals. The molecular basis of spore dormancy and resistance is not understood, but the physical state of water in the different spore compartments is thought to play a key role. To characterize this water in situ, we recorded the water 2H and 17O spin relaxation rates in D2O-exchanged Bacillus subtilis spores over a wide frequency range. The data indicate high water mobility throughout the spore, comparable with binary protein–water systems at similar hydration levels. Even in the dense core, the average water rotational correlation time is only 50 ps. Spore dormancy therefore cannot be explained by glass-like quenching of molecular diffusion but may be linked to dehydration-induced conformational changes in key enzymes. The data demonstrate that most spore proteins are rotationally immobilized, which may contribute to heat resistance by preventing heat-denatured proteins from aggregating irreversibly. We also find that the water permeability of the inner membrane is at least 2 orders of magnitude lower than for model membranes, consistent with the reported high degree of lipid immobilization in this membrane and with its proposed role in spore resistance to chemicals that damage DNA. The quantitative results reported here on water mobility and transport provide important clues about the mechanism of spore dormancy and resistance, with relevance to food preservation, disease prevention, and astrobiology. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Proceedings of the National Academy of Sciences
volume
106
issue
46
pages
19334 - 19339
publisher
National Acad Sciences
external identifiers
  • wos:000271907400022
  • scopus:73349109182
ISSN
1091-6490
DOI
10.1073/pnas.0908712106
language
English
LU publication?
yes
id
6b8d9a52-239a-43f7-a742-2155453d2a57 (old id 1502424)
date added to LUP
2009-11-11 17:20:30
date last changed
2017-12-10 03:40:42
@article{6b8d9a52-239a-43f7-a742-2155453d2a57,
  abstract     = {The bacterial spore, the hardiest known life form, can survive in a metabolically dormant state for many years and can withstand high temperatures, radiation, and toxic chemicals. The molecular basis of spore dormancy and resistance is not understood, but the physical state of water in the different spore compartments is thought to play a key role. To characterize this water in situ, we recorded the water 2H and 17O spin relaxation rates in D2O-exchanged Bacillus subtilis spores over a wide frequency range. The data indicate high water mobility throughout the spore, comparable with binary protein–water systems at similar hydration levels. Even in the dense core, the average water rotational correlation time is only 50 ps. Spore dormancy therefore cannot be explained by glass-like quenching of molecular diffusion but may be linked to dehydration-induced conformational changes in key enzymes. The data demonstrate that most spore proteins are rotationally immobilized, which may contribute to heat resistance by preventing heat-denatured proteins from aggregating irreversibly. We also find that the water permeability of the inner membrane is at least 2 orders of magnitude lower than for model membranes, consistent with the reported high degree of lipid immobilization in this membrane and with its proposed role in spore resistance to chemicals that damage DNA. The quantitative results reported here on water mobility and transport provide important clues about the mechanism of spore dormancy and resistance, with relevance to food preservation, disease prevention, and astrobiology.},
  author       = {Persson Sunde, Erik and Setlow, Peter and Hederstedt, Lars and Halle, Bertil},
  issn         = {1091-6490},
  language     = {eng},
  number       = {46},
  pages        = {19334--19339},
  publisher    = {National Acad Sciences},
  series       = {Proceedings of the National Academy of Sciences},
  title        = {The physical state of water in bacterial spores.},
  url          = {http://dx.doi.org/10.1073/pnas.0908712106},
  volume       = {106},
  year         = {2009},
}