2ol8
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The crystal structure of OspA mutant
OverviewOverview
We investigated how the register between adjacent beta-strands is, specified using a series of mutants of the single-layer beta-sheet (SLB), in Borrelia OspA. The single-layer architecture of this system eliminates, structural restraints imposed by a hydrophobic core, enabling us to, address this question. A critical turn (turn 9/10) in the SLB was replaced, with a segment with an intentional structural mismatch. Its crystal, structure revealed a one-residue insertion into the central beta-strand, (strand 9) of the SLB. This insertion triggered a surprisingly large-scale, structural rearrangement: (i) the central strand (strand 9) was shifted by, one residue, causing the strand to flip with respect to the adjacent, beta-strands and thus completely disrupting the native side-chain, contacts; (ii) the three-residue turn located on the opposite end of the, beta-strand (turn 8/9) was pushed into its preceding beta-strand (strand, 8); (iii) the register between strands 8 and 9 was shifted by three, residues. Replacing the original sequence for turn 8/9 with a stronger, turn motif restored the original strand register but still with a flipped, beta-strand 9. The stability differences of these distinct structures were, surprisingly small, consistent with an energy landscape where multiple, low-energy states with different beta-sheet configurations exist. The, observed conformations can be rationalized in terms of maximizing the, number of backbone H-bonds. These results suggest that adjacent, beta-strands "stick" through the use of factors that are not highly, sequence specific and that beta-strands could slide back and forth, relatively easily in the absence of external elements such as turns and, tertiary packing.
About this StructureAbout this Structure
2OL8 is a Single protein structure of sequence from Borrelia burgdorferi. Full crystallographic information is available from OCA.
ReferenceReference
Beta-strand flipping and slipping triggered by turn replacement reveal the opportunistic nature of beta-strand pairing., Makabe K, Yan S, Tereshko V, Gawlak G, Koide S, J Am Chem Soc. 2007 Nov 28;129(47):14661-9. Epub 2007 Nov 7. PMID:17985889
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