Histidine residues have been hypothesized to function as sensors of environmental pH that can trigger the activity of viral fusion proteins. We investigated a requirement for histidine residues in the envelope (E) protein of West Nile virus during pH-dependent entry into cells. Each histidine was individually replaced with a nonionizable amino acid and tested functionally. In each instance, mutants capable of orchestrating pH-dependent infection were identified. These results do not support a requirement for any single histidine as a pH-sensing "switch," and they suggest that additional features of the E protein are involved in triggering pH-dependent steps in the flavivirus life cycle.
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| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2786769 | PMC |
| http://dx.doi.org/10.1128/JVI.01072-09 | DOI Listing |
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