Crystallization and preliminary X-ray crystallographic studies of the ice-binding protein from the Arctic yeast Leucosporidium sp. AY30

Abstract

Freezing is dangerous to cellular organisms because it causes an increase in the concentration of ions and other solutes in the plasma, denatues biomolecules and ruptures cell membranes. Some cold-adapted organisms can sruvive at subzero temperatures by producing proteins that bind to and inhibit the growth of ice cystals. To better understand the structure and function of these proteins, the ice-binding protein form Leucosporidium sp. AY30 (LeIBP) was over-expressed, purified and crystallized. The native crystal belonged to space group P432121, with unit-cell parameters a=b=98.05, c=106.13A. Since LeIBP lacks any cysteine or methionine residues, two leucine residues were substituted by methionine residues. The selenomethionine-substituted mutant crystallized in the same space group as the native protein.o temperatures by producing proteins that bind to and inhibit the growth of ice cystals. To better understand the structure and function of these proteins, the ice-binding protein form Leucosporidium sp. AY30 (LeIBP) was over-expressed, purified and crystallized. The native crystal belonged to space group P432121, with unit-cell parameters a=b=98.05, c=106.13A. Since LeIBP lacks any cysteine or methionine residues, two leucine residues were substituted by methionine residues. The selenomethionine-substituted mutant crystallized in the same space group as the native protein.