Conservation of the Cold Shock Domain Protein Family in Plants

In this paper, we report the widespread occurrence of the nucleic acid-binding cold shock domain (CSD) in plants and identify the first eukaryotic homologs that are nearly identical to bacterial cold shock proteins (CSP). Using Arabidopsis as a model system, we determined that its four unique CSD genes are differentially regulated in response to low temperature. Prokaryotic response to low temperature has been extensively studied inEscherichia coli and is accompanied by a spectacular accumulation of nucleic acid-binding CSPs (Graumann and Marahiel, 1998; Yamanaka et al., 1998;Bae et al., 2000). CspA, the most prominent of the nine-member E. coli CSP family, accumulates up to 10% of total proteins during cold stress (Jiang et al., 1997). The three-dimensional structure of E. coli CspA forms a five-stranded β-barrel structure (Newkirk et al., 1994; Schindelin et al., 1994) that contains two consensus RNA-binding motifs (RNP1 and RNP2), which facilitate nucleic acid recognition/binding (Schroder et al., 1995). CspA has been hypothesized to prevent RNA secondary structure formation (Jiang et al., 1997), thereby enhancing translation at low temperature.