residues on the β-strands are involved in binding RNA, with specificity toward
“CCAAT” or “ATTGG” sequence. Owing to the design of prokaryotic transcriptional machinery, the cold-induced RNA secondary structure may impose premature
transcription termination. The functional significance of bacterial Csps is therefore
directly related to the formation of stable secondary RNA structures in response to
low temperature stress (Polissi et al. 2003).
6.11 Cold Acclimation Proteins (Caps) or Cold Resistance
Protein (CRP)
Cold tolerant bacteria produce permanently one set of proteins called cold acclimation proteins (Caps) during continuous growth at low temperature. Caps may be
fundamental to life in the cold and ensure improved protein synthesis at low
temperature (Margesin et al. 2007). Cold acclimation proteins are comparable to
Csps and are continuously synthesized during prolonged growth at low temperatures
and differentiate psychrotrophs from mesophiles. In cold-adapted bacteria
(in mesophiles), some of the caps were identified as cold shock proteins, and a
typical example being the RNA chaperone CspA (Ray 2006). It has been proposed
that cold acclimatization proteins are essential for the maintenance of both growth
and cell cycle at low temperatures, but their function is still poorly understood.
Nucleotide sequence of CapA, a gene encoding a protein of the CspA family in
psychrotrophic bacterium A. globiformis SI55, when compared with that of other
CspA related protein from various sources showed that the cold shock response in
A. globiformis SI55 is an adaptive process that enables cells to protect themselves
from deleterious effects of cold (Berger et al. 1996). Radiolabelling of total cellular
proteins of Pseudomonas spp. 30-3 revealed elevated expression of an 8 kDa protein
at 4
C, which suggests that the protein CapB plays a pivotal role in survival and
tolerance at cold and subzero temperatures (Panicker et al. 2002). Similarly a 248 bp
DNA fragment in Pseudomonas spp. 30-3 that was amplified using CapB gene
specific primers showed a 98% amino acid sequence homology with CapB of
Pseudomonas fragi and 62% homology with CspA of E.coli (Michel et al. 1997;
Panicker et al. 2002). Cold shock proteins (Csps) from Pseudomonas fluorescens
(MTCC 103) and cold resistance proteins from its mutant CRPF 2 of 14 and 35 kDa,
respectively, were purified and expression level was checked at different
temperatures, i.e., 4, 10, 20, 30, and 37
C. The expression of Csps and CRP
increases with decrease in temperature and the cell wall thickness of mutant
exhibited two-fold increase, thus facilitating low temperature survival (Khan et al.
2003).
Antarctic sea ice microorganism Colwellia sp. NJ341 could grow at temperatures
À5 to 22
C, which provided an excellent model system to study microbial adaptation to cold temperatures. To examine such a cold-adaptation mechanism at the
protein level, Colwellia sp. NJ341 was grown at 0, 8, and 15
C. The results of
SDS-PAGE analysis revealed that Colwellia sp. NJ341 responded to the low temperature by inducing the synthesis of a set of proteins. Several bands increased in
200
P. K. Mishra et al.
“CCAAT” or “ATTGG” sequence. Owing to the design of prokaryotic transcriptional machinery, the cold-induced RNA secondary structure may impose premature
transcription termination. The functional significance of bacterial Csps is therefore
directly related to the formation of stable secondary RNA structures in response to
low temperature stress (Polissi et al. 2003).
6.11 Cold Acclimation Proteins (Caps) or Cold Resistance
Protein (CRP)
Cold tolerant bacteria produce permanently one set of proteins called cold acclimation proteins (Caps) during continuous growth at low temperature. Caps may be
fundamental to life in the cold and ensure improved protein synthesis at low
temperature (Margesin et al. 2007). Cold acclimation proteins are comparable to
Csps and are continuously synthesized during prolonged growth at low temperatures
and differentiate psychrotrophs from mesophiles. In cold-adapted bacteria
(in mesophiles), some of the caps were identified as cold shock proteins, and a
typical example being the RNA chaperone CspA (Ray 2006). It has been proposed
that cold acclimatization proteins are essential for the maintenance of both growth
and cell cycle at low temperatures, but their function is still poorly understood.
Nucleotide sequence of CapA, a gene encoding a protein of the CspA family in
psychrotrophic bacterium A. globiformis SI55, when compared with that of other
CspA related protein from various sources showed that the cold shock response in
A. globiformis SI55 is an adaptive process that enables cells to protect themselves
from deleterious effects of cold (Berger et al. 1996). Radiolabelling of total cellular
proteins of Pseudomonas spp. 30-3 revealed elevated expression of an 8 kDa protein
at 4
C, which suggests that the protein CapB plays a pivotal role in survival and
tolerance at cold and subzero temperatures (Panicker et al. 2002). Similarly a 248 bp
DNA fragment in Pseudomonas spp. 30-3 that was amplified using CapB gene
specific primers showed a 98% amino acid sequence homology with CapB of
Pseudomonas fragi and 62% homology with CspA of E.coli (Michel et al. 1997;
Panicker et al. 2002). Cold shock proteins (Csps) from Pseudomonas fluorescens
(MTCC 103) and cold resistance proteins from its mutant CRPF 2 of 14 and 35 kDa,
respectively, were purified and expression level was checked at different
temperatures, i.e., 4, 10, 20, 30, and 37
C. The expression of Csps and CRP
increases with decrease in temperature and the cell wall thickness of mutant
exhibited two-fold increase, thus facilitating low temperature survival (Khan et al.
2003).
Antarctic sea ice microorganism Colwellia sp. NJ341 could grow at temperatures
À5 to 22
C, which provided an excellent model system to study microbial adaptation to cold temperatures. To examine such a cold-adaptation mechanism at the
protein level, Colwellia sp. NJ341 was grown at 0, 8, and 15
C. The results of
SDS-PAGE analysis revealed that Colwellia sp. NJ341 responded to the low temperature by inducing the synthesis of a set of proteins. Several bands increased in
200
P. K. Mishra et al.