3wp9

Publication Abstract from PubMed

Antifreeze proteins (AFPs) are structurally diverse macromolecules that bind to ice crystals and inhibit their growth to protect organism from injuries caused by freezing. An AFP identified from an Antarctic bacterium, Colwellia sp. strain SLW05 (ColAFP) is homologous to AFPs from a wide variety of psychrophilic microorganisms. To understand the antifreeze function of ColAFP, we have characterized the antifreeze activity and determined the crystal structure of this protein. The recombinant ColAFP exhibited thermal hysteresis activity of approximately 4 degrees C at a concentration of 0.14 mM and induced a rapid growth of ice crystals in the hexagonal direction. Fluorescence-based ice plane affinity analysis showed that ColAFP binds to multiple planes of ice including the basal plane. These observations classify ColAFP as a hyperactive AFP. The crystal structure of ColAFP determined at 1.6-A resolution revealed an irregular beta-helical structure, which is similar to known homologs. Mutational and molecular docking studies clarified that ColAFP binds to ice through a compound ice-binding site (IBS) located at a flat surface of the beta-helix and the adjoining loop region. The IBS of ColAFP lacks repetitive sequences which has been recognized as a characteristic of hyperactive AFPs. These results conclude that ColAFP exerts antifreeze activity by utilizing its compound IBS, which is distinct from the characteristic feature of IBS shared by other hyperactive AFPs. This study represents a novel aspect for protection from freezing achieved by AFPs in psychrophilic microorganisms. This article is protected by copyright. All rights reserved.

Hyperactive antifreeze protein from an Antarctic sea ice bacterium Colwellia sp. has a compound ice-binding site without repetitive sequences.,Hanada Y, Nishimiya Y, Miura A, Tsuda S, Kondo H FEBS J. 2014 Jun 17. doi: 10.1111/febs.12878. PMID:24938370^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.