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PDBsum entry 2g8c
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Lipid binding protein
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PDB id
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2g8c
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References listed in PDB file
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Key reference
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Title
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Atomic-Resolution crystal structure of borrelia burgdorferi outer surface protein a via surface engineering.
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Authors
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K.Makabe,
V.Tereshko,
G.Gawlak,
S.Yan,
S.Koide.
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Ref.
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Protein Sci, 2006,
15,
1907-1914.
[DOI no: ]
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PubMed id
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Abstract
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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.
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Figure 1.
Figure 1. (A) Superposition of the OspA structure in the 184.1 Fab complex (1OSP; blue) and that of OspAsm1 (red). Only the
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The above figure is
reprinted
by permission from the Protein Society:
Protein Sci
(2006,
15,
1907-1914)
copyright 2006.
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