@article{oai:repo.qst.go.jp:00049084,
 author = {Mahatabuddin , Sheikh and Fukami , Daichi and Arai, Tatsuya and Nishimiya, Yoshiyuki and Shimizu, Rumi and Shibazaki , Chie and Kondo , Hidemasa and Adachi, Motoyasu and Tsuda, Sakae and Shimizu, Rumi and Shibazaki, Chie and Adachi, Motoyasu},
 issue = {21},
 journal = {Proceedings of the National Academy of Sciences of United States of America},
 month = {May},
 note = {Recently, polypentagonal water networks were observed in a protein capable of binding to ice crystals, or ice-binding protein (IBP). To examine such water networks and clarify their role in ice-binding, we determined X-ray crystal structures of a 65-residue defective isoform of an IBP (wild type, WT) and its 5 single mutants (A20L, A20G, A20T, A20V, and A20I). Polypentagonal water networks composed of approximately 50 semi-clathrate waters were solely observed on the strongest A20I mutant, which appeared to include a tetrahedral water cluster exhibiting perfect position match to the (10-10) 1st prism plane of a single ice crystal. Inclusion of another symmetrical water cluster in the polypentagonal network showed a perfect complementarity to the waters constructing the (20-21) pyramidal ice plane. The order of ice-binding strength was A20L < A20G < WT< A20T < A20V < A20I, where the top 3 mutants capable of binding to the 1st 12 prism and the pyramidal ice planes commonly contained a bifurcated γ-CH313 -group. These results suggest that a fine-tuning of the protein surface assisted by a side-chain group regulates the holding property of the polypentagonal water network, whose function is to freeze the host protein to specific ice planes.},
 pages = {5456--5461},
 title = {Polypentagonal ice-like water networks emerge solely in an activity-improved variant of ice-binding protein},
 volume = {115},
 year = {2018}
}