Crystal structure of Vibrio cholerae neuraminidase reveals dual lectin-like domains in addition to the catalytic domain  Susan Crennell, Elspeth Garman, Graeme Laver, Eric Vimr, Garry Taylor  Structure  Volume 2, Issue 6, Pages 535-544 (June 1994) DOI: 10.1016/S0969-2126(00)00053-8

Figure 1 Views of cholera NA. (a) Stereoview of the Cα backbone. (b) and (c) MOLSCRIPT [44] drawings of orthogonal views of cholera NA. Colouring: amino-terminal wing-1 in pink; the canonical neuraminidase domain coloured from red to violet, with wing-2 in pale green. The calcium ion is drawn as a grey sphere. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 1 Views of cholera NA. (a) Stereoview of the Cα backbone. (b) and (c) MOLSCRIPT [44] drawings of orthogonal views of cholera NA. Colouring: amino-terminal wing-1 in pink; the canonical neuraminidase domain coloured from red to violet, with wing-2 in pale green. The calcium ion is drawn as a grey sphere. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 1 Views of cholera NA. (a) Stereoview of the Cα backbone. (b) and (c) MOLSCRIPT [44] drawings of orthogonal views of cholera NA. Colouring: amino-terminal wing-1 in pink; the canonical neuraminidase domain coloured from red to violet, with wing-2 in pale green. The calcium ion is drawn as a grey sphere. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 2 Topology of cholera NA. β -strands depicted by arrows, α -helices by open boxes, and Asp-boxes by shaded boxes. Four Asp-boxes have the Ser-X-Asp- X-Gly-X-Thr/Asn-Trp motif and are in topologically equivalent positions to those in salmonella NA, but there is a fifth ‘Asp- box’ from residue 335 in a topologically equivalent position with sequence Tyr-Asp-Val-Ala-Ser-Gly-Asn-Trp. The β -sandwich of each lectin-like wing is formed by closing the sheets about the vertical line running through each wing. The chain runs from residue 25–781. Residues 1–24 code a leader peptide which is removed before release into the extracellular medium. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 3 (a), (b) MOLSCRIPT [44] drawings of orthogonal views of the two wings, viewed after superposition of wing-2 onto wing-1 as detailed in Table 1. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 3 (a), (b) MOLSCRIPT [44] drawings of orthogonal views of the two wings, viewed after superposition of wing-2 onto wing-1 as detailed in Table 1. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 4 MOLSCRIPT [44] wings of orthogonal views of wing-1 (a) and (e) in comparison with various lectins. (b) and (f) Comparison with coral tree lectin (1LTE). The calcium ion is drawn as a dark grey sphere, the manganese ion as a light grey sphere, and bound lactose is also shown. (c) and (g) Comparison with human serum amyloid protein (SAP). The calcium ions are drawn as dark spheres. (d) and (h) Comparison with bovine spleen S-lectin (1SLT). The view in (b)–(d) is from the same direction as (a), (f)–(h) are viewed from the same direction as (e). The coordinates of the lectins have been transformed following superposition onto wing-1 as detailed in Table 1. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 5 DANA inhibitor in the 4.5 å cholera NA difference Fourier electron density map (contoured at 3σ). The fit of DANA to the map was not optimized, but results from an optimized superposition of salmonella NA + DANA [14] onto the cholera NA catalytic domain using O [39]. An initial fit of the Cα atoms of 10 residues conserved in the active sites of both enzymes gave an rms deviation of 0.77 å, with an improved fit of 1.96 å for 256 Cα atoms. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 6 MOLSCRIPT and Raster 3D (E Merritt unpublished program) drawings of the active sites of (a) cholera NA, showing residues within 5 å of DANA, and the position of the Ca2+ ion essential for activity, (b) salmonella NA showing residues which interact with DANA [14], and (c) influenza NA from virus A/tern/Australia/G70C/75 NA, an N9 subtype, showing residues which interact with DANA [26]. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 6 MOLSCRIPT and Raster 3D (E Merritt unpublished program) drawings of the active sites of (a) cholera NA, showing residues within 5 å of DANA, and the position of the Ca2+ ion essential for activity, (b) salmonella NA showing residues which interact with DANA [14], and (c) influenza NA from virus A/tern/Australia/G70C/75 NA, an N9 subtype, showing residues which interact with DANA [26]. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 6 MOLSCRIPT and Raster 3D (E Merritt unpublished program) drawings of the active sites of (a) cholera NA, showing residues within 5 å of DANA, and the position of the Ca2+ ion essential for activity, (b) salmonella NA showing residues which interact with DANA [14], and (c) influenza NA from virus A/tern/Australia/G70C/75 NA, an N9 subtype, showing residues which interact with DANA [26]. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 7 Position of the essential Ca2+ in cholera NA. The seven ligands to the Ca2+ ion in cholera NA are the carbonyl oxygen of Ala 253, the carbonyl and Oδ oxygens of Asn256, both carboxyl oxygens of Asp289 and the carbonyl and Oγ oxygens of Thr313. Distances range from 2.21 å to 2.62 å. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)

Figure 8 Quality of the final 2.3 å 2Fo–Fc electron density map, contoured at 1σ showing part of the hydrophobic β -sandwich filling of wing-2. Structure 1994 2, 535-544DOI: (10.1016/S0969-2126(00)00053-8)