Polynucleotide phosphorylase binds to ssRNA with same affinity as to ssDNA.
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.
Bermúdez-Cruz
Rosa Ma
RM
Departamento de Genética y Biología Molecular, Centro de Investigación y Estudios Avanzados del IPN, Apdo. Postal 14-740, 07000, Mexico, Mexico.
García-Mena
Jaime
J
Montañez
Cecilia
C
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
D020121:5' Untranslated Regions; D004277:DNA, Single-Stranded; D012333:RNA, Messenger; D011994:Recombinant Proteins; D011117:Polyribonucleotide Nucleotidyltransferase