Transcriptomic identification and expression analysis of cold shock domain protein (CSP) genes in the marine dinoflagellate Prorocentrum minimum

Dinoflagellates are frequently exposed to cold-water temperatures, and some may survive in winter and in polar regions. Cold shock domain proteins (CSPs) seem to function as part of their adaptation to such stressful environments. In this study, we identified two CSP genes (PmCSP1 and PmCSP2) in the marine dinoflagellate Prorocentrum minimum, characterized their structural properties, and investigated their expression patterns in response to cold shock and heavy metal exposure. Putative PmCSP1 (96 aa, 10.1 kDa) and PmCSP2 (91 aa, 9.4 kDa) proteins had two consensus RNA-binding motifs and might be localized in the cytoplasm, due to the absence of a signal peptide. Phylogenetic analyses revealed that PmCSPs clustered with those of other dinoflagellates and had been recycled between genomic DNA and mRNA. Real-time PCR revealed that PmCSPs significantly responded to low temperatures, but not to nickel or cadmium. These genes may allow the organism to adapt to and survive in cold habitats and winter.