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Applied and Environmental Microbiology, September 2000, p. 3756-3763, Vol. 66, No. 9
Laboratory of Food Microbiology, Wageningen
University and Research Center, Wageningen,1
and Microbial Ingredients Section, NIZO Food Research,
Ede,2 The Netherlands
Received 18 January 2000/Accepted 13 June 2000
The physiological and regulatory effects of overproduction of five
cold shock proteins (CSPs) of Lactococcus lactis were
studied. CspB, CspD, and CspE could be overproduced at high levels (up to 19% of the total protein), whereas for CspA and CspC limited overproduction (0.3 to 0.5% of the total protein) was obtained. Northern blot analysis revealed low abundance of the cspC
transcript, indicating that the stability of cspC mRNA is
low. The limited overproduction of CspA is likely to be caused by low
stability of CspA since when there was an Arg-Pro mutation at position
58, the level of CspA production increased. Using two-dimensional gel
electrophoresis, it was found that upon overproduction of the CSPs
several proteins, including a number of cold-induced proteins of
L. lactis, were induced. Strikingly, upon overproduction of
CspC induction of CspB, putative CspF, and putative CspG was also
observed. Overproduction of CspB and overproduction of CspE result in
increased survival when L. lactis is frozen (maximum increases, 10- and 5-fold, respectively, after 4 freeze-thaw cycles). It is concluded that in L. lactis CSPs play a regulatory
role in the cascade of events that are initiated by cold shock
treatment and that they either have a direct protective effect during
freezing (e.g., RNA stabilization) or induce other factors involved in the freeze-adaptive response or both.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Physiological and Regulatory Effects of Controlled Overproduction
of Five Cold Shock Proteins of Lactococcus lactis
MG1363
and
*
Corresponding author. Mailing address: Laboratory of
Food Microbiology, Wageningen University and Research Center, Bomenweg 2, 6703 HD Wageningen, The Netherlands. Phone: 31-317-484981. Fax:
31-317-484893. E-mail:
Tjakko.Abee{at}micro.fdsci.wau.nl.
Present address: Department of Genetics, University of
Groningen, 9750 AA Haren, The Netherlands.
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