Transcriptome-wide analysis of DEAD-box RNA helicase gene family in an Antarctic psychrophilic alga Chlamydomonas sp. ICE-L

Abstract

DEAD-box RNA helicase family proteins have been identified in almost all living organisms. Some of them play a crucial role in adaptation to environmental changes and stress response, especially in the low-temperature acclimation in different kinds of organisms. Compared with the full swing study in plants and bacteria, the characters and functions of DEAD-box family proteins had not been surveyed in algae. To identify genes critical for freezing acclimation in algae, we screened DEAD-box RNA helicase genes from the transcriptome sequences of a psychrophilic microalga Chlamydomonas sp. ICE-L which was isolated from Antarctic sea ice. Totally 39 DEAD-box RNA helicase genes had been identified. Most of the DEAD-box RNA helicase have 1:1 homologous relationships in Chlamydomonas reinhardtii and Chlamydomonas sp. ICE-L with several exceptions. The homologous proteins in ICE-L to the helicases critical for cold or freezing tolerance in Arabidopsis thaliana had been identified based on phylogenetic comparison studies. The response of these helicase genes is not always identical in the Chlamydomonas sp. ICE-L and Arabidopsis under the same low-temperature treatment. The expression of several DEAD-box RNA helicase genes including CiRH5, CiRH25, CiRH28, and CiRH55 were significantly up-regulated under freezing treatment of ICE-L and their function in freezing acclimation of ICE-L deserved further investigation.

Specific adaptations are selected in opposite sun exposed Antarctic cryptoendolithic communities as revealed by untargeted metabolomics

“…Recent studies reported an up-regulations of a highly diverse set of metabolic features to cope cold-associated stresses; for instance, in an Antarctic alga Chlamydomonas sp., RNA helicase genes were up-regulated after low temperature exposure [57,58], while, photosynthetic metabolism in Chaetoceros neogracile, isolated from Antarctic ocean, was found highest at 4˚C than at room temperature [59]; earlier, a protease was found to be produced in higher amount at low temperature in the Antarctic yeast Candida humicola [60]. However, given the many different adaptive mechanisms that are used by different psychrophiles, many other strategies for survival at cold temperatures are still to be discovered [61].…”