An extracellular ice-binding glycoprotein from an Arctic psychrophilic yeast

A psychrophilic yeast was isolated from an Arctic pond and its culture supernatant showed ice-binding activity This isolate, identified as Leucosporidium sp. based on an analysis of the D1/D2 and ITS regions of its ribosomal DNA, produced a secretory ice-binding protein (IBP) Yeast IBP was purified from the culture medium to near homogeneity by the ice affinity method and appeared to be glycosylated with a molecular mass of similar to 26 kDa In addition, the yeast IBP was shown to have thermal hysteresis (TH) and recrystallization inhibition (RI) activities The full-length cDNA for yeast IBP was determined and was found to encode a 261 amino acid protein with molecular weight of 26 8 kDa that includes an N-terminal signal peptide and one potential N-glycosylation site The deduced protein showed high sequence identity with other IBPs and hypothetical IBPs from fungi, diatoms, and bacteria, Clustering with a class of ice-active proteins (C) 2010 Elsevier Inc All rights reserved