Gene expression cold-inducible

Despite many studies on the effect of ABA on plant tissues there is no demonstration that ABA can regulate the level of enzyme activities and specially of those involved in cold acclimation. On the other hand, ABA certainly induces modifications in gene expression and many genes are modulated by ABA (Skriver Mundy, 1990). Indeed several in vivo protein-labelling and in vitro translation experiments have demonstrated that the level of certain proteins or mRNAs increased in response to both low temperature and exogenous ABA applications (Robertson et al., 1987 Mohapatra et al., 1988 Ling et al., 1989). 

The discoveries of Csp s and trigger factor may represent the tip of a large iceberg. In view of the pervasive effects of low temperature on the structures of all classes of macromolecules, it is reasonable to conjecture that many more types of proteins will be discovered whose roles are to offset the effects of cold shock on the cell. Some of these molecules may be expressed constitutively and may be part of the normal machinery of the cell. For example, certain ribosomal proteins are thought to function as RNA chaperones, and if present in sufficient amounts, these proteins may allow the cell to cope with the effects of cold shock on the structures of certain classes of RNAs. In yeast, a constitutively expressed ribosomal protein has helicase activity, and mutation in the gene encoding the protein confers on the cells a cold-sensitive phenotype (Schmid and Linder, 1992). Perhaps the apparent absence of cold-induced RNA chaperones in eukaryotic cells is... 

In our laboratory, reduced temperature at induction is the first thing attempted to increase the solubility of an expressed protein. Frequently, reducing the induction temperature from 37 to 15—20 °C can change the solubility level of an overproduced protein from undetectable to adequate.82 Reduced temperature slows both transcription and translation rates and reduces the strength of hydrophobic interactions. However, below 15 °C many promoter systems are inefficient. For these very low temperatures, use of cold-inducible promoters can be advantageous as most commonly used promoter systems work with reduced efficiency at decreased temperatures.83-85 Systems based on the promoter from the major E. coli cold-shock gene cspA have been described and have demonstrated their utility with membrane-associated proteins as well as those prone to proteolysis.86,87... 

Carter, A. D., Walling, M. J., and Hamer, D. H., 1983, Distinct promoter and control sequences of an inducible metallothionein gene, in Enhancer and Eukaryotic Gene Expression (Y. Gluzman and T. Shenk, eds.), pp. 170-174, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York. 

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