2guv
From Proteopedia
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| , resolution 1.40Å | |||||||
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| Gene: | lpp, mlpA, mulI (Escherichia coli) | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Conformational Transition between Four- and Five-stranded Phenylalanine Zippers Determined by a Local Packing Interaction
Overview
Alpha-helical coiled coils play a crucial role in mediating specific protein-protein interactions. However, the rules and mechanisms that govern helix-helix association in coiled coils remain incompletely understood. Here we have engineered a seven heptad "Phe-zipper" protein (Phe-14) with phenylalanine residues at all 14 hydrophobic a and d positions, and generated a further variant (Phe-14(M)) in which a single core Phe residue is substituted with Met. Phe-14 forms a discrete alpha-helical pentamer in aqueous solution, while Phe-14(M) folds into a tetrameric helical structure. X-ray crystal structures reveal that in both the tetramer and the pentamer the a and d side-chains interlock in a classical knobs-into-holes packing to produce parallel coiled-coil structures enclosing large tubular cavities. However, the presence of the Met residue in the apolar interface of the tetramer markedly alters its local coiled-coil conformation and superhelical geometry. Thus, short-range interactions involving the Met side-chain serve to preferentially select for tetramer formation, either by inhibiting a nucleation step essential for pentamer folding or by abrogating an intermediate required to form the pentamer. Although specific trigger sequences have not been clearly identified in dimeric coiled coils, higher-order coiled coils, as well as other oligomeric multi-protein complexes, may require such sequences to nucleate and direct their assembly.
About this Structure
2GUV is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Conformational transition between four and five-stranded phenylalanine zippers determined by a local packing interaction., Liu J, Zheng Q, Deng Y, Kallenbach NR, Lu M, J Mol Biol. 2006 Aug 4;361(1):168-79. Epub 2006 Jun 13. PMID:16828114
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