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. Author manuscript; available in PMC: 2014 Aug 28.
Published in final edited form as: J Am Chem Soc. 2013 Aug 15;135(34):10.1021/ja407445x. doi: 10.1021/ja407445x

Figure 3.

Figure 3

(A) The tetrameric X-ray structure of AmpDh3 in complex with the reaction products for turnover of 22. Each subunit is colored differently to show the embrace by the four in the middle of the tetramer. The reaction products seen in the crystal structure are shown for monomers B and B′, whose active sites are facing the viewer (the peptide stems in green and the saccharides in magenta). The other two active sites are on the opposite side of the tetramer. The NMR-based structure of the crosslinked peptidoglycan (in black) is superimposed on the coordinates for the products from the X-ray structure. (B) A cartoon for the complex showing the perspective down the axis of the peptidoglycan saccharide backbone (shown in open circles; viewed from 12 o’clock down in panel A). The peptides are shown symbolically as black lines. The three-fold symmetry for the peptidoglycan is shown down the axis of the saccharide backbones. The processivity of the action of AmpDh3 tetramer is shown by the arrows, as the pivoting of the enzyme on the saccharide backbone takes it to the next sites of reaction on the opposite face of the tetramer.