Structural basis for the antifreeze activity of an ice-binding protein from an Arctic yeast
- Structural basis for the antifreeze activity of an ice-binding protein from an Arctic yeast
- Other Titles
- 북극효모유래 결빙방지단백질의 구조연구
- Lee, Jun Hyuck
Kim, Hak Jun
Lee, Sung Gu
- Antifreeze protein; Ice-binding protein; Leucosporidium sp.
- Issue Date
- Lee, Jun Hyuck, et al. 2012. Structural basis for the antifreeze activity of an ice-binding protein from an Arctic yeast. 한국생물공학회. 한국생물공학회. 2012.06.01~.
- Arctic yeast Leucosporidium sp. produces a glycosylated ice-binding protein (LeIBP) with a molecular mass of approximately 25 kDa, which can lower the freezing point
below the melting point once it binds to ice. LeIBP is a member of a large class of ice-binding proteins, the structures of which are unknown. Here, we report the crystal
structures of non-glycosylated LeIBP and glycosylated LeIBP at 1.57 A and 2.43 A resolution, respectively. Structural analysis of the LeIBPs revealed a dimeric
right-handed β-helix fold, which is composed of three parts: a large coiled structural domain, a long helix region (residues 96?115 form a long α-helix that packs along one
face of the β-helix) and a C-terminal hydrophobic loop region (243-PFVPAPEVV-251). Unexpectedly, the C-terminal hydrophobic loop region has an extended conformation
pointing away from the body of the coiled structural domain and forms intertwined dimer interactions. In addition, structural analysis of glycosylated LeIBP with sugar
moieties attached to Asn185 provides a basis for interpreting previous biochemical analyses as well as the increased stability and secretion of glycosylated LeIBP. We also
determined that the aligned Thr/Ser/Ala residues are critical for ice binding within the B face of LeIBP using site-directed mutagenesis. Although LeIBP has a common β-helical
fold similar to that of canonical hyperactive antifreeze proteins, the ice-binding site is more complex and does not have a simple ice-binding motif. In conclusion, we could
identify the ice-binding site of LeIBP and discuss differences in the ice-binding modes compared to other known AFPs and IBPs.
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