title: Polynucleotide phosphorylase binds to ssRNA with same affinity as to ssDNA.
abstract: Polynucleotide phosphorylase (PNPase, polyribonucleotide nucleotidyltransferase, EC 2.7.7.8) is a multifunctional protein, with a 3'-5' processive exoribonuclease, a Pi exchange, an RNA polymerase and an autoregulatory activity. The interaction between this enzyme and the mRNA target is crucial for its activities. In the present study, we characterized the interaction of PNPase with its mRNA regulatory region and ssRNA, as well as with ssDNA and dsDNA by determining K(d). Our results indicate that PNPase has high affinity for its mRNA, ssRNA and for ssDNA (K(d) approximately 10-20 nM). However, this enzyme exhibits a lower affinity for dsDNA (K(d) approximately 200-1400 nM). Possible implications of these results on the molecular mechanisms by which PNPase is regulated and degrades mRNA are discussed.
authors.affiliation: Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del IPN, Apdo. Postal 14-740, 07000, Mexico, Mexico.
authors.forename: Rosa Ma
authors.initials: RM
authors.lastname: Bermúdez-Cruz
authors.forename: Jaime
authors.initials: J
authors.lastname: García-Mena
authors.forename: Cecilia
authors.initials: C
authors.lastname: Montañez
mesh_terms: D020121:5' Untranslated Regions / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D004277:DNA, Single-Stranded / Q000235:genetics / Q000378:metabolism*; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D016014:Linear Models; D008969:Molecular Sequence Data; D010957:Plasmids; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism*; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism
chemical_list: D020121:5' Untranslated Regions; D004277:DNA, Single-Stranded; D012333:RNA, Messenger; D011994:Recombinant Proteins; D011117:Polyribonucleotide Nucleotidyltransferase