1n4i
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(New page: 200px<br /><applet load="1n4i" size="450" color="white" frame="true" align="right" spinBox="true" caption="1n4i" /> '''Solution structure of spruce budworm antifre...)
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Revision as of 20:25, 24 November 2007
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Solution structure of spruce budworm antifreeze protein at 5 degrees celsius
Overview
Antifreeze proteins (AFPs) prevent the growth of ice, and are used by some, organisms that live in sub-zero environments for protection against, freezing. All AFPs are thought to function by an adsorption inhibition, process. In order to elucidate the ice-binding mechanism, the structures, of several AFPs have been determined, and have been shown to consist of, different folds. Recently, the first structures of the highly active, insect AFPs have been characterized. These proteins have a beta-helix, structure, which adds yet another fold to the AFP family. The 90-residue, spruce budworm (Choristoneura fumiferana) AFP consists of a beta-helix, with 15 residues per coil. The structure contains two ranks of aligned, threonine residues (known as the TXT motif), which were shown by, mutagenesis experiments to be located in the ice-binding face. In our, previous NMR study of this AFP at 30 degrees C, we found that the TXT face, was not optimally defined because of the broadening of NMR resonances, potentially due to weak oligomerization. We present here a structure of, spruce budworm AFP determined at 5 degrees C, where this broadening is, reduced. In addition, the 1H-15N NMR dynamics of the protein were examined, at 30 degrees C and 5 degrees C. The results show that the spruce budworm, AFP is more structured at 5 degrees C, and support the general observation, that AFPs become more rigid as the temperature is lowered.
About this Structure
1N4I is a Single protein structure of sequence from Choristoneura fumiferana. Full crystallographic information is available from OCA.
Reference
Spruce budworm antifreeze protein: changes in structure and dynamics at low temperature., Graether SP, Gagne SM, Spyracopoulos L, Jia Z, Davies PL, Sykes BD, J Mol Biol. 2003 Apr 11;327(5):1155-68. PMID:12662938
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