Molecular cloning and expression analysis of a cytosolic Hsp70 gene from Antarctic ice algae Chlamydomonas sp. ICE-L

• DOI: 10.1007/s00792-010-0313-8
• Publication Date: 2010-04-07T00:46:34Z
• Authors: Shenghao Liu; Pengying Zhang; Bailin Cong; Chenlin Liu; Xuezheng Lin; Jihong Shen; Xiaohang Huang
• Keywords: Adenosine Triphosphatases; 0303 health sciences; DNA, Complementary; Time Factors; Base Sequence; Sequence Homology, Amino Acid; Chlamydomonas; Ice; Molecular Sequence Data; Antarctic Regions; Eukaryota; Plants; 03 medical and health sciences; Cytosol; Gene Expression Regulation; HSP70 Heat-Shock Proteins; Amino Acid Sequence; Cloning, Molecular; Molecular Chaperones

A cDNA encoding heat shock protein 70 of Antarctic ice algae Chlamydomonas sp. ICE-L (designated as CiHsp70) was identified by RT-PCR and rapid amplification of cDNA ends approaches. The full-length cDNA of CiHsp70 was 2,232 bp, consisting of a 5'-terminal untranslated region (UTR) of 76 bp, a 3'-terminal UTR of 203 bp with a poly (A) tail, and an open reading frame of 1,953 bp. The CiHsp70 cDNA encoded a polypeptide of 651 amino acids with an ATPase domain of 388 amino acids, the substrate peptide binding domain of 246 amino acids and a C-terminus domain of 17 amino acids. The inducible CiHsp70 cDNA was highly homologous to other plant cytosolic Hsp70 genes and clustered together with green algae and higher plant rather than brown algae, diatom and Cryptophyta. Antarctic ice algae were treated with different stress conditions and messenger RNA (mRNA) expression levels of CiHsp70 were quantified by quantitative RT-PCR. The results showed that both cold and heat shock treatments could stimulate CiHsp70 mRNA expression. Meanwhile, CiHsp70 mRNA expression level increased 2.9-fold in response to UV-B radiation for 6 h, while the expression levels of CiHsp70 were remarkably increased after removing the UV-B radiation and immediately providing additional 6 h visible light. Furthermore, treating with 62 or 93 per thousand NaCl for 2 h, CiHsp70 mRNA expression level increased 3.0- and 2.1-fold, respectively. Together, our observations revealed that CiHsp70 as a molecular chaperone might play an important role in Antarctic ice algae Chlamydomonas sp. ICE-L acclimatizing to polar environment.