Point mutations were introduced in the nucleic acid sequence to modify the sequence of NAH to make it more like NAA. The enzyme activity was assessed.

(a) Explain how changing a single nucleotide can change the sequence of the protein.

(b) Given what is known about the neuraminidase enzyme, describe what is measured to provide the results in Figure 2 and Figure 3.

(c) Predict whether an NAH virus with an N234Y substitution will be a rapid spreading or slow spreading virus.

(d) Justify your prediction.

A researcher was trying to determine why a strain of influenza spreads more easily than other strains. She suspected that the answer might lie in the Influenza Neuraminidase (NA) protein. NA is an enzyme known to play a role in releasing viral particles during viral spread. It functions by cleaving an attachment between viral particles and the cell membrane. The researcher evaluated the enzyme activity of each of the strains and found them to be quite different. She then compared the NA protein from the rapidly spreading strain of flu (NAH) with the NA protein from another strain of flu (NAA). The sequences were similar, but there were some differences in the amino acid sequence.

Transcribed Image Text:

-NA NAA NA Neuraminidase Activity (x10* a.u.) NAH NA, N234Y NA, 1257M NA K286E H Neuraminidase Activity (%NAH) H 100 120