2guv
From Proteopedia
Conformational Transition between Four- and Five-stranded Phenylalanine Zippers Determined by a Local Packing Interaction
Structural highlights
FunctionLPP_ECOLI Interacts with the peptidoglycan both covalently and noncovalently. This interaction contributes to the maintenance of the structural and functional integrity of the cell envelope. Evolutionary ConservationCheck, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedAlpha-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. 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[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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Categories: Escherichia coli | Large Structures | Deng Y | Kallenbach NR | Liu J | Lu M | Zheng Q