2oop

From Proteopedia

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Revision as of 09:26, 23 January 2008

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Structure of Tyr7-PYY in solution

Overview

The minimal model system to study the basic principles of protein folding, is the hairpin. The formation of beta-hairpins, which are the basic, components of antiparallel beta-sheets, has been studied extensively in, the past decade, but much less is known about helical hairpins. Here, we, probe hairpin formation between a polyproline type-II helix and an, alpha-helix as present in the natural miniprotein peptide YY (PYY). Both, turn sequence and interactions of aromatic side chains from the C-terminal, alpha-helix with the pockets formed by N-terminal Pro residues are shown, by site-directed mutagenesis and solution NMR spectroscopy in different, solvent systems to be important determinants of backbone dynamics and, hairpin stability, suggesting a close analogy with some beta-hairpin, structures. It is shown that multiple relatively weak contacts between the, helices are necessary for the formation of the helical hairpin studied, here, whereas the type-I beta-turn acts like a hinge, which through, certain single amino acid substitutions is destabilized such that hairpin, formation is completely abolished. Denaturation and renaturation of, tertiary structure by temperature or cosolvents were probed by measuring, changes of chemical shifts. Folding of PYY is both reversible and, cooperative as inferred from the sigmoidal denaturation curves displayed, by residues at the interface of the helical hairpin. Such miniproteins, thus feature an important hallmark of globular proteins and should provide, a convenient system to study basic aspects of helical hairpin folding that, are complementary to those derived from studies of beta-hairpins.

About this Structure

2OOP is a Single protein structure of sequence from Sus scrofa with as ligand. Full crystallographic information is available from OCA.

Reference

Probing the formation of stable tertiary structure in a model miniprotein at atomic resolution: determinants of stability of a helical hairpin., Neumoin A, Mares J, Lerch-Bader M, Bader R, Zerbe O, J Am Chem Soc. 2007 Jul 18;129(28):8811-7. Epub 2007 Jun 20. PMID:17580866

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