Expression of Ice-Binding Protein under Freezing condition from Antarctic Sea Ice Diatom, Chaetoceros neogracile.

Abstract

Expression of Ice-Binding Protein under Freezing condition from Antarctic Sea Ice Diatom, Chaetoceros neogracile.

InGyu GWAK1, Woong-Sic JUNG2, Sung-Ho KANG2 and EonSeon JIN*1

1Dept. of Life Science, Hanyang University, Seoul 133-791, Korea. 2Polar Environmental Research Division, Korea Ocean Polar Research Institute (KOPRI), Incheon 426-744, Korea.

Sea ice diatoms grow well under low temperature and high salinity environmental condition, and these diatoms are responsible for a considerable part of Antarctic photosynthesis. Their successful growth may due to the part to secretion of ice binding protein (IBP) that have ice recrystallization inhibition activity and to have the ability to act as cryoprotectants. We have isolated a cDNA encoding Ice binding protein (IBP) from Antarctic diatom (Chaetoceros neogracile). The deduced amino acid sequence consists of a polypeptide with 282 amino acids, this sequence is similar to the known IBP of Navicular sp. IBP cDNA contains signal peptide sequences. Southern blot analysis revealed that IBP is multigene family. The level of IBP mRNA was strongly increased by freezing stress. C. neogracile IBP was over expressed in E. coli and partially purified. We will discuss about possible application of IBP from Antarctic algae.