Nuclear localization of the influenza A virus nonstructural proteins, NS1 and NS2.
Item
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Title
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Nuclear localization of the influenza A virus nonstructural proteins, NS1 and NS2.
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Identifier
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AAI8821085
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identifier
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8821085
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Creator
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Greenspan, Deborah.
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Contributor
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Adviser: Peter Palese
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Date
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1988
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Language
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English
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Publisher
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City University of New York.
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Subject
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Biology, Molecular
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Abstract
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The smallest RNA segment of influenza A viruses encodes the nonstructural proteins, NS1 and NS2. Although the genomic organization of these mRNAs is defined little is known about the functions of the proteins for which they encode. In this thesis, experiments were done to further characterize the NS1 and NS2 proteins of influenza virus. First, the nonstructural NS2 protein of influenza A/PR/8/34 virus was efficiently expressed in bacteria and monospecific antisera were prepared against the bacterially synthesized polypeptide. The antisera were used in immunofluorescence experiments to localize the NS2 protein to the nucleus during influenza virus infection. Before the availability of this reagent, the NS2 protein had erroneously been localized to the cytoplasm by cell fractionation studies.;Second, sequence analysis of the NS gene of A/turkey/Oregon/71 and an influenza B virus, clone 201, revealed nucleotide deletions resulting in truncated NS1 proteins approximately half the size of those of other influenza viruses. These shortened NS1 polypeptides were shown to retain their karyophilic pattern by immunofluorescence analysis thus indicating that large deletions in the carboxyl termini of these proteins can be tolerated without affecting the functional integrity of the polypeptides in tissue culture.;Finally, the NS1 protein has been shown to enter the nucleus of virus infected cells independent of any other influenza virus protein suggesting that this polypeptide contains within its sequence the information coding for its nuclear location. To define the nuclear signal of the NS1 protein, a series of recombinant SV40 vectors expressing deletion mutants or fusion proteins were constructed and these proteins were analyzed. Two nuclear localization signals were defined for the NS1 protein. One nuclear localization signal (NLS1) contains the stretch of basic amino acids Asp-Arg-Leu-Arg-Arg (codons 34-38). The second nuclear localization signal (NLS2) is defined within amino acid region 203-237. These signals are similar to previously defined nuclear signal sequences of other proteins. In addition, the presence of NLS 1 and NLS 2 In the NS1 protein may represent an example of signal redundancy within a protein.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
