Site-directed mutagenesis of the avian retrovirus nucleocapsid protein, pp12, at serine 40, the primary site of phosphorylation in vivo

X. Fu, P. T. Tuazon, J. A. Traugh, J. Leis

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15 Scopus citations

Abstract

The major nucleocapsid protein of avian retroviruses, pp12, binds to single-stranded viral RNA with high affinity. Phosphorylation at Ser-40 is necessary for this binding. In order to examine the role of phosphorylation of serine 40 in the biological function of pp12, we have introduced a series of amino acid substitutions at this position in the Rous sarcoma virus (Pr-C) protein. Substitution of threonine, alanine, or three other amino acids for Ser-40 had very little or no detectable effect on viral replication, nor did the control substitution of glycine for Ser-43, a nonphosphorylated residue. In vivo and in vitro, the Ala-40 and probably the Thr-40 substituted p12 proteins are phosphorylated at alternative sites which are phosphorylated to a minor extent in vivo in the wild type protein. A study of the RNA binding properties of Ala-40 substituted p12 has indicated that the protein has been stabilized in a high affinity RNA binding state which is independent of phosphorylation. The viability of the Ala-40 mutant virus indicates that this high binding affinity may be required for biological activity.

Original languageEnglish (US)
Pages (from-to)2134-2139
Number of pages6
JournalJournal of Biological Chemistry
Volume263
Issue number5
StatePublished - 1988

Funding

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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