psychrophiles than seen in mesophiles (15–20
C). Cold shock response involves the
induction and synthesis of cold shock proteins (Csps), for the regulation of protein
synthesis and m-RNA folding (Ray 2006).
The first identified member of the family is CspA from E. coli, whose
homologues were subsequently identified from several bacteria (Graumann et al.
1996; Thieringer et al. 1998; Herbraud and Potier 1999). CspA homologues, in fact,
are the most conspicuous group of protein at low temperature in any bacteria. In the
case of E. coli upon cold shock these homologues constitute more than 10% of total
cellular proteins. Among the nine homologues, only four (CspA, CspB, CspG, and
CspI) are cold inducible in E. coli (Yamanaka 1999; Phadtare and Inouye 2004). In
Gram-positive bacterium B. subtilis, CspB of the three homologues (CspB, CspC,
and CspD) is cold inducible (Graumann et al. 1996, Kaan et al. 2002). This suggests
that there is a functional redundancy, as well as probable division of labor among the
members of the group. In fact, E. coli with only quadruple deletion but not double or
triple deletions of cspA, cspB, cspG, and cspI genes are cold sensitive (Phadtare and
Inouye 2004).
Csp-like proteins were found in more than 50 other bacterial species (Graumann
and Marahiel 1998). CspA-like proteins have also been identified in psychrotrophic
bacteria: Pseudomonas fragi (Hebraud et al. 1994), Arthrobacter globiformis
(Berger et al. 1996), and Yersinia enterocolitica (Neuhaus et al. 2000). In addition,
an FKBP family protein was involved in cold adaptation of psychrotrophic bacteria
Shewanella sp. SIB1 (Suzuki et al. 2004). The cold shock proteins identified in
psychrotrophic bacteria and their properties are listed in Table 6.1.
In the Antarctic psychrotrophic P. fluorescens, the cspA is induced within 30 min
when the cultures are shifted from 22
C (optimum temperature) to 4
C (cold stress
temperature) (Ray et al. 1998). Similar results were obtained with another
psychrotrophic strain P. fragi, a refrigerated food spoiling bacterium (Hebraud
et al. 1994). The transfer of the food-borne pathogen Listeria monocytogenes from
30 to 5
C was characterized by the sharp induction of 18 kDa molecular mass
protein that shared a complete sequence identity with a Listeria innocua non-heme
iron-binding ferritin protein. The purification of these ferritin-like proteins (Flp)
revealed a native molecular mass of about 100–110 kDa and a polypeptide composed of six 18 kDa-subunits indicated that these polypeptides might be responsible
for cold adaptation (Hébraud and Guzzo 2000).
In another study, cold-adapted strains of R. leguminosarum bv. viciae were
compared with a poorly adapted strain and a cold-sensitive strain for freezing
survival, protein induction, and fatty acid composition following a cold shock
from 25
C to 10, 5, and 0
C. A common 6.1 kDa cold shock protein was induced
in all the strains, but the total number of cold shock proteins synthesized at 0
C was
higher in the cold-adapted strains than in the cold-sensitive strains (Drouin et al.
2000). Transgenic E. coli cells expressing the cold-adapted chaperones (Cpn 60 and
Cpn 10) from the psychrophilic bacterium Oleispira antarctica were found to grow
at 4
C. By co-immunoprecipitation of Cpn 60, Northern blot, and in vitro refolding,
it was systematically identified that protein–chaperone interactions are the key
determinants of protein function at low temperatures (Strocchi et al. 2006).
198
P. K. Mishra et al.
C). Cold shock response involves the
induction and synthesis of cold shock proteins (Csps), for the regulation of protein
synthesis and m-RNA folding (Ray 2006).
The first identified member of the family is CspA from E. coli, whose
homologues were subsequently identified from several bacteria (Graumann et al.
1996; Thieringer et al. 1998; Herbraud and Potier 1999). CspA homologues, in fact,
are the most conspicuous group of protein at low temperature in any bacteria. In the
case of E. coli upon cold shock these homologues constitute more than 10% of total
cellular proteins. Among the nine homologues, only four (CspA, CspB, CspG, and
CspI) are cold inducible in E. coli (Yamanaka 1999; Phadtare and Inouye 2004). In
Gram-positive bacterium B. subtilis, CspB of the three homologues (CspB, CspC,
and CspD) is cold inducible (Graumann et al. 1996, Kaan et al. 2002). This suggests
that there is a functional redundancy, as well as probable division of labor among the
members of the group. In fact, E. coli with only quadruple deletion but not double or
triple deletions of cspA, cspB, cspG, and cspI genes are cold sensitive (Phadtare and
Inouye 2004).
Csp-like proteins were found in more than 50 other bacterial species (Graumann
and Marahiel 1998). CspA-like proteins have also been identified in psychrotrophic
bacteria: Pseudomonas fragi (Hebraud et al. 1994), Arthrobacter globiformis
(Berger et al. 1996), and Yersinia enterocolitica (Neuhaus et al. 2000). In addition,
an FKBP family protein was involved in cold adaptation of psychrotrophic bacteria
Shewanella sp. SIB1 (Suzuki et al. 2004). The cold shock proteins identified in
psychrotrophic bacteria and their properties are listed in Table 6.1.
In the Antarctic psychrotrophic P. fluorescens, the cspA is induced within 30 min
when the cultures are shifted from 22
C (optimum temperature) to 4
C (cold stress
temperature) (Ray et al. 1998). Similar results were obtained with another
psychrotrophic strain P. fragi, a refrigerated food spoiling bacterium (Hebraud
et al. 1994). The transfer of the food-borne pathogen Listeria monocytogenes from
30 to 5
C was characterized by the sharp induction of 18 kDa molecular mass
protein that shared a complete sequence identity with a Listeria innocua non-heme
iron-binding ferritin protein. The purification of these ferritin-like proteins (Flp)
revealed a native molecular mass of about 100–110 kDa and a polypeptide composed of six 18 kDa-subunits indicated that these polypeptides might be responsible
for cold adaptation (Hébraud and Guzzo 2000).
In another study, cold-adapted strains of R. leguminosarum bv. viciae were
compared with a poorly adapted strain and a cold-sensitive strain for freezing
survival, protein induction, and fatty acid composition following a cold shock
from 25
C to 10, 5, and 0
C. A common 6.1 kDa cold shock protein was induced
in all the strains, but the total number of cold shock proteins synthesized at 0
C was
higher in the cold-adapted strains than in the cold-sensitive strains (Drouin et al.
2000). Transgenic E. coli cells expressing the cold-adapted chaperones (Cpn 60 and
Cpn 10) from the psychrophilic bacterium Oleispira antarctica were found to grow
at 4
C. By co-immunoprecipitation of Cpn 60, Northern blot, and in vitro refolding,
it was systematically identified that protein–chaperone interactions are the key
determinants of protein function at low temperatures (Strocchi et al. 2006).
198
P. K. Mishra et al.