β-Helix structure and ice-binding properties of a hyperactive antifreeze protein from an insect

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阅读量：

145

作者：

SP Graether，MJ Kuiper，SM Gagné，VK Walker，Z Jia，BD Sykes，PL Davies

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摘要：

Insect antifreeze proteins (AFP) are considerably more active at inhibiting ice crystal growth than AFP from fish or plants. Several insect AFPs, also known as thermal hysteresis proteins, have been clonedand expressed. Their maximum activity is 3–4 times that of fish AFPsand they are 10–100 times more effective at micromolar concentrations. Here we report the solution structure of spruce budworm () AFP and characterize its ice-binding properties. The 9-kDa AFP is a β-helix with a triangular cross-section and rectangular sides that form stacked parallel β-sheets; a fold which is distinct from the three known fish AFP structures. The ice-binding side contains 9 of the 14 surface-accessible threonines organized in a regular array of TXT motifs that match the ice lattice on both prism and basal planes. In support of this model, ice crystal morphology and ice-etching experiments are consistent with AFP binding to both of these planes and thus may explain the greater activity of the spruce budworm antifreeze.

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关键词：

binding proteins freezing ice ice nucleation proteins threonine

DOI：

10.1038/35018610

被引量：

803