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. 2020 Feb 5;9:e51247. doi: 10.7554/eLife.51247

Figure 1. Molecular architecture of LtgA alpha helix 30 and contacts made with reaction.

intermediates. (a) Native structure of LtgA. Ribbon model of LtgA displaying a helical structure consisting of 37 alpha helices. LtgA consists of three domains: A C-domain (gray and red), which houses the putative catalytic domain, and the L (yellow) and U (green) domains, which are of unknown function. A long N-terminal extension interacts with the L-domain, which closes the structure (PDB ID: 5O29). Clear and consistent density for helix 30 was depicted by the Fo-Fc omit map (green) (b) LtgA with a disordered conformation of helix 30. Clear and consistent density for helix 30 was absent as depicted by the Fo-Fc omit map (green) of helix 30 (PDB ID: 6H5F). (c) LtgA plus trapped intermediates (chitotetraose and a GlcNAc sugar) (PDB ID: 5O2N). (d) LtgA plus anhydro product (1,6-anhydro-chitotriose) (PDB ID: 5OIJ).

Figure 1.

Figure 1—figure supplement 1. Conservation of alpha helix 30 amongst diverse lytic transglycosylases.

Figure 1—figure supplement 1.

Phylogenetic tree of lytic transglycosylases from various organisms complemented with various structures or predicted structures of lytic transglycosylases highlighing the conserved alpha helix 30 (PDB: protein data bank).

Figure 1—figure supplement 2. Binding of LtgA to the Peptidoglycan.

Figure 1—figure supplement 2.

Heterologously expressed purified proteins of LtgA E481, LtgA E508A, and LtgAΔ30 were tested for their ability to bind Neiserria PG. Equal concentrations of purified protein (5 μg) were mixed with Neisseria PG and subjected to high-speed centrifugation. The western blot reflects proteins bound to insoluble PG. Comparatively, LtgAΔ30 appears to be defective in PG binding.