Cold-shock domain

Both the heat and cold shock response are universal and have been studied extensively. The major heat shock proteins (HSPs) are highly conserved. They are involved in the homeostatic adaptation of cells to harsh environmental conditions. Some act as molecular chaperones for protein folding, while others are involved in the processing of denatured polypeptides whose accumulation would be deleterious. The cold shock results in the transient induction of cold shock proteins (CSPs), which include a family of small acidic proteins carrying the cold shock domain. The CSPs appear to be involved in various cellular functions such as transcription, translation and DNA recombination. 

Hunt, S. L., Hsuan, J. J., Totty, N., and Jackson, R. J. (1999). Unr, a cellular cytoplasmic RNA-binding protein with five cold-shock domains, is required for internal initiation of translation of human rhinovirus RNA. Genes Dev. 13, 437—448. 

Graumann, P.L., and M.A. Marahiel (1998). A superfamily of proteins that contain the cold-shock domain. Trends Biochem. Sci. 23 286-290. 

A group of proteins that are synthesized by plant cells, prokaryotic cells, and eukaryotic cells in response to cold stress. It has been suggested that cold-shock proteins (CSPs) function as chaperones for mRNA. See Graumann, P.L. and Marshiel, M. A., A superfamily of proteins that contain the cold-shock domain, Trends Biochem. Sci. 23,286-290,1998 Phadtare,... 

Alsina, J., and Inouye, M., Cold-shock response and cold-shock proteins, Curr. Opin. Microbiol. 2, 175-180, 1999 Sommerville, J., Activities of cold-shock domain proteins in translational control, Bioessays 21, 319-325,1999 Graumann, P.L. andMarahiel, M.A., Cold shock response in Bacillus subtilis, J. Mol. Microbiol. Biotechnol. 1, 203-209, 1999 Loa, D.A. and Murata, N., Responses to cold shock in cyanobacteria, J. Mol. Microbiol. Biotechnol. 1, 221-230,1999 Ermolenko, D.N. and Makhatadze,... 

The fastest-folding small proteins generally fold on much slower time scales than the time scale of formation of secondary structure. The speed record is currently held by lambda(6-85), a truncated, monomeric form of the N-terminal domain of lambda repressor, which refolds with a half-life of approximately 140 fjis. A thermostable lambda(6-85) variant with alanine substituted for glycine residues 46 and 48 in the third helix folds faster in dilute solutions of de-naturant, with an extrapolated half-life of less than 10 /us in water.13 Cold-shock protein CspB from Bacillus subtilis folds in about 1 ms.61 Engineered mutants of the P22 Arc repressor62 and CI263 fold in a fraction of a millisecond. 

This methodology was similarly applied to cold shock proteins (CSP) [81]. They are a family of small single domain proteins, with a highly conserved sequence identity [82,83]. The known structures of CSPs consist of a secondary structure of two amphipathic /3-sheets. The first /3-sheet is formed by three antiparallel /3-strands and the second contains two anti-parallel /3-strands. These two /3-sheets form a hydrophobic core and a predominantly hydrophilic surface [84]. Many mutational forms of these proteins have been studied experimentally and hence they can be used as a model to study the effects of mutations on folding stability and mechanisms. 

SchindeHn, H., Marahiel, M.A., Heinemann, U. Universal nucleic acid-binding domain revealed by crystal-structure of the BaciUus-subtilis major cold-shock protein. Nature 1993,364,164-8. 

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