Characterization of Ice-Binding Protein from Antarctic Sea Ice Diatom, Chaetoceros Neogracile

Abstract

CHARACTERIZATION OF ICE-BINDING PROTEIN FROM ANTARCTIC SEA ICE DIATOM, CHAETOCEROS NEOGRACILE I.G. Gwak1, W.S. Jung2, S.H. Kang2, E.S. Jin1 1 - Hanyang Uni. Department of Life Science, Seoul, Korea 2 - KOPRI, Polar Environmental Research Division, Incheon, Korea firsthero0515@hanmail.net

Polar sea ice diatoms grow well under low temperature and high salinity environmental condition, and these diatoms are responsible for a conciderable part of Antarctic photosynthesis. Their successful growth may due to the secretion of macromolecules that have ice recrystallization inhibition activity and to the ability to act as cryoprotectants. Ice-binding protein (IBP) is one of these molecules. These proteins cause pitting and other irregularities on the surface of growing ice crystals. In this study, we isolated IBP cDNA from Antarctic sea ice diatom, Chaetoceros neogracile and characterized this protein. C. neogracile IBP showed 61% identity of sequence homology with Navicula glaciei IBP-8 based on the alignment of amino acid sequences. Besides, we investigated the copy number of IBP in C. neogracile using Southern blot analysis. We are under examining the activity of E. coil expressed IBP to bind ice and morphological change of ice crystal. And we carry out northern blot analysis for the expression level of IBP mRNA under the freezing stess.