Snow mold fungus, Typhula ishikariensis, secretes seven antifreeze protein isoforms (denoted TisAFPs) that assist in the survival of the mold under snow cover. Here, the X-ray crystal structure of a hyperactive isoform, TisAFP8, at 1.0 Å resolution is presented. TisAFP8 folds into a right-handed β-helix accompanied with a long α-helix insertion. TisAFP8 exhibited significantly high antifreeze activity that is comparable with other hyperactive AFPs, despite its close structural and sequence similarity with the moderately active isoform TisAFP6. A series of mutations introduced into the putative ice-binding sites (IBSs) in the β-sheet and adjacent loop region reduced antifreeze activity. A double-mutant A20T/A212S, which comprises a hydrophobic patch between the β-sheet and loop region, caused the greatest depression of antifreeze activity of 75%, when compared with that of the wild-type protein. This shows that the loop region is involved in ice binding and hydrophobic residues play crucial functional roles. Additionally, bound waters around the β-sheet and loop region IBSs were organized into an ice-like network and can be divided into two groups that appear to mediate separately TisAFP and ice. The docking model of TisAFP8 with the basal plane via its loop region IBS reveals a better shape complementarity than that of TisAFP6. In conclusion, we present new insights into the ice-binding mechanism of TisAFP8 by showing that a higher hydrophobicity and better shape complementarity of its IBSs, especially the loop region, may render TisAFP8 hyperactive to ice binding.
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November 2016
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From untargeted plasma metabolomics from carriers affected with the FMR1 premutation and control subjects, putative target proteins were identified which were used as input data to build a protein-protein interaction network. Please see pp. 3871–3888 for further information. Image provided by C. Guilivi.
Research Article|
October 27 2016
Hydrophobic ice-binding sites confer hyperactivity of an antifreeze protein from a snow mold fungus
Jing Cheng;
Jing Cheng
1Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan
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Yuichi Hanada;
Yuichi Hanada
*
1Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan
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Ai Miura;
Ai Miura
2Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan
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Sakae Tsuda;
Sakae Tsuda
1Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan
2Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan
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Hidemasa Kondo
Hidemasa Kondo
1Graduate School of Life Science, Hokkaido University, Kita 10, Nishi 8, Kita-ku, Sapporo 060-0810, Japan
2Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology, 2-17-2-1 Tsukisamu-Higashi, Toyohira-ku, Sapporo 062-8517, Japan
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Publisher: Portland Press Ltd
Received:
June 02 2016
Revision Received:
September 07 2016
Accepted:
September 09 2016
Accepted Manuscript online:
September 09 2016
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© 2016 The Author(s); published by Portland Press Limited on behalf of the Biochemical Society
2016
Biochem J (2016) 473 (21): 4011–4026.
Article history
Received:
June 02 2016
Revision Received:
September 07 2016
Accepted:
September 09 2016
Accepted Manuscript online:
September 09 2016
Citation
Jing Cheng, Yuichi Hanada, Ai Miura, Sakae Tsuda, Hidemasa Kondo; Hydrophobic ice-binding sites confer hyperactivity of an antifreeze protein from a snow mold fungus. Biochem J 1 November 2016; 473 (21): 4011–4026. doi: https://doi.org/10.1042/BCJ20160543
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