2g8c

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spinqualitylabelsall models 2g8c, resolution 1.15Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Atomic-resolution crystal structure of Borrelia burgdorferi OspA via surface entropy reduction

Overview

Outer surface protein A (OspA) from Borrelia burgdorferi has an unusual, dumbbell-shaped structure in which two globular domains are connected with, a "single-layer" beta-sheet (SLB). The protein is highly soluble, and it, has been recalcitrant to crystallization. Only OspA complexes with Fab, fragments have been successfully crystallized. OspA contains a large, number of Lys and Glu residues, and these "high entropy" residues may, disfavor crystal packing because some of them would need to be immobilized, in forming a crystal lattice. We rationally designed a total of 13 surface, mutations in which Lys and Glu residues were replaced with Ala or Ser. We, successfully crystallized the mutant OspA without a bound Fab fragment and, extended structure analysis to a 1.15 Angstroms resolution. The new, high-resolution structure revealed a unique backbone hydration pattern of, the SLB segment in which water molecules fill the "weak spots" on both, faces of the antiparallel beta-sheet. These well-defined water molecules, provide additional structural links between adjacent beta-strands, and, thus they may be important for maintaining the rigidity of the SLB that, inherently lacks tight packing afforded by a hydrophobic core. The, structure also revealed new information on the side-chain dynamics and on, a solvent-accessible cavity in the core of the C-terminal globular domain., This work demonstrates the utility of extensive surface mutation in, crystallizing recalcitrant proteins and dramatically improving the, resolution of crystal structures, and provides new insights into the, stabilization mechanism of OspA.

About this Structure

2G8C is a Single protein structure of sequence from Borrelia burgdorferi with IMD and PG4 as ligands. Full crystallographic information is available from OCA.

Reference

Atomic-resolution crystal structure of Borrelia burgdorferi outer surface protein A via surface engineering., Makabe K, Tereshko V, Gawlak G, Yan S, Koide S, Protein Sci. 2006 Aug;15(8):1907-14. Epub 2006 Jul 5. PMID:16823038

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