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Unique mRNA Cap Binding Properties of Pokeweed Antiviral Protein: Fluorescence Studies of Equilibrium Interactions
Author(s) -
Friedland Diana Elaine,
Tumer Nilgun E.,
Goss Dixie J.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a108-d
Subject(s) - ribosome inactivating protein , ricin , depurination , messenger rna , ribosome , binding site , rna , chemistry , microbiology and biotechnology , biochemistry , ribosomal binding site , ribosomal rna , biology , dna , gene , toxin
Ribosome inactivating proteins (RIP)’s have been used as both anti‐viral agents and instruments for biological warfare. Ricin and pokeweed antiviral protein (PAP) both have N‐glycosidase activity that removes a specific adenine from the highly conserved sarcin/ricin (S/R) loop in the large rRNA. Translational inhibition by ribosome depurination has been hypothesized to be responsible for RIP’s cytotoxicity. It has since been reported that PAP also interacts with mRNA cap structure. Affinity chromatography has been used to show that PAP binds to the m 7 Gppp cap of mRNA (1). Here, we report fluorescence binding studies which directly measure equilibrium interaction of PAP with cap. Our preliminary evidence indicates the presence of two binding sites. We measure a high affinity (nM) binding and a lower affinity (μM) event which takes place during the course of cap binding. As PAP depurinates both mRNA and the S/R loop of rRNA, these two binding sites may be functionally related. Detailed further investigations will be reported.