2ol8: Difference between revisions

Revision as of 19:19, 21 February 2008

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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 ==Overview==
-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.
+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 Structure==
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 [[Category: membrane protein]]
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Wed Jan 23 11:43:22 2008''
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 18:19:48 2008''