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Figure 2.
Fig. 2. Structures of  -repeat segments in
PSAMs. (A) The backbone structure of the -repeat segment in the
crystal structure of OspA+3bh-sm1. The hydrogen bonds between
backbone atoms are shown as dashed lines. (B) Side chain
conformations of the -repeat segment of
OspA+3bh. Only the residues on the front face of the -sheet
are shown. The -sheet backbone is shown
as arrows. For clarity, the turn regions are omitted. The three
cross-strand amino acid ladders are labeled with their
respective amino acid compositions ("F/L," "E/K," and "T/I").
These ladders extend short and/or imperfect ones present in
wild-type OspA ("FLFV," "EKEK," and "TVTI," respectively) (14).
(C) Superposition of a total of 26 copies of the -hairpin
unit from the PSAM crystal structures. The backbone of the
original -hairpin unit from
wild-type OspA is shown in green. Amino acid resides in the -strand
regions are labeled with an uppercase letter and residue number.
Strand residues labeled in black have their side chain pointing
toward the reader, and those labeled in gray have their side
chain pointing away from the reader. Residues in the turn
regions are labeled with a lowercase letter.
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