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NOVEL ICE‐BINDING PROTEINS FROM A PSYCHROPHILIC ANTARCTIC ALGA (CHLAMYDOMONADACEAE, CHLOROPHYCEAE) 1
Author(s) -
Raymond James A.,
Janech Michael G.,
Fritsen Christian H.
Publication year - 2009
Publication title -
journal of phycology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.85
H-Index - 127
eISSN - 1529-8817
pISSN - 0022-3646
DOI - 10.1111/j.1529-8817.2008.00623.x
Subject(s) - antifreeze protein , biology , psychrophile , algae , botany , chlorophyceae , biochemistry , chlorophyta , enzyme
Many cold‐adapted unicellular plants express ice‐active proteins, but at present, only one type of such proteins has been described, and it shows no resemblance to higher plant antifreezes. Here, we describe four isoforms of a second and very active type of extracellular ice‐binding protein (IBP) from a unicellular chlamydomonad alga collected from an Antarctic intertidal location. The alga is a euryhaline psychrophile that, based on sequences of the alpha tubulin gene and an IBP gene, appears to be the same as a snow alga collected on Petrel Island, Antarctica. The IBPs, which do not resemble any known antifreezes, have strong recrystallization inhibition activity and have an ability to slow the drainage of brine from sea ice. These properties, by maintaining liquid environments, may increase survival of the cells in freezing environments. The IBPs have a repeating TXT motif, which has previously been implicated in ice binding in insect antifreezes and a ryegrass antifreeze.