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. 2007 Mar;71(1):158–229. doi: 10.1128/MMBR.00036-06

FIG. 11.

FIG. 11.

The TonB box. (A) Sequence alignments of TonB boxes. Shown are sequence alignments of the BtuB, Cir, FecA, FepA, and FhuA (upper panel) and of the colicin B, D, Ia/Ib, M, and 5/10 and pesticin TonB boxes (lower panel). Conserved residues are in boldface type. (B) BtuB TonB box interactions with TonB. Shown are in vivo cysteine disulfide cross-linking data for the TonB region around Gln160 (green) and the BtuB TonB box (blue). The antiparallel interaction between the β-strands is shown, as observed in the crystal structure. (Reprinted from reference 588 with permission of AAAS.) Solid lines indicate cross-links observed between TonB and BtuB (67). Dotted lines indicate cross-links observed between TonB and FecA, with the FecA TonB box aligned with the BtuB TonB box (492).