Figure 2 - Analysis of Cal0409 NA.

From the following article

Extrapolating from sequence—the 2009 H1N1 'swine' influenza virus

Venkataramanan Soundararajan, Kannan Tharakaraman, Rahul Raman, S Raguram, Zachary Shriver, V Sasisekharan & Ram Sasisekharan

Nature Biotechnology 27, 510 - 513 (2009)


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A homology-based structural model of Cal0409 NA was constructed using the N1 NA crystal structure (PDB ID: 3CKZ) as a template. (a) Active site of the Cal0409 neuraminidase (dark gray) docked with sialic acid (carbon; light gray) is shown highlighting key contacts including a dense network of hydrogen bonds (black broken lines) in the proximity of the C6 substitution (hydrogen atoms not displayed). Amino acid side chains are shown with carbon atoms colored purple. Oseltamivir and zanamivir were docked from their native co-crystal structures N1 NA–oseltamivir (PDB ID: 2HU0/2HU4) and N8 NA–zanamivir (PDB ID: 2HTQ) onto the Cal0409 NA structural model. (b) Comparison of contacts made by oseltamivir (carbon; cyan) with the wild-type (carbon; purple) and His274Tyr mutant (carbon; green) of Cal0409 NA shows the shift in Glu276 (caused by Tyr274 in the mutant) toward oseltamivir potentially resulting in unfavorable interactions (red broken circle) with the hydrophobic substitution in the C6 position. (c) Comparison of contacts made by zanamivir (carbon; yellow) with wild-type (carbon; purple) and His274Tyr mutant (carbon; green) of Cal0409 NA shows that the shift in the position of Glu276 toward the polar C6 substitution of zanamivir may provide additional favorable contacts (dark green broken circle). The oxygen and nitrogen atoms are colored red and blue, respectively, in all the structures.