title: In vitro processing activity of Bacillus subtilis polynucleotide phosphorylase.
abstract: A phosphate-dependent exonuclease activity was identified in purified protein fractions from Bacillus subtilis that were selected for binding to poly(I)-poly(C) agarose. Based on the characteristics of the degradation products and the absence of this activity in a pnpA strain, which contains a transposon insertion in the B. subtilis PNPase gene (Luttinger et al., 1996--accompanying paper), this exonuclease activity was shown to be due to polynucleotide phosphorylase (PNPase). Processive 3'-to-5' exonucleolytic degradation of an SP82 phage RNA substrate was stalled at a particular site. Structure probing of the RNA showed that the stall site was downstream of a particular stem-loop structure. A similar stall site was observed for an RNA that comprised the intergenic region between the B. subtilis rpsO and pnpA genes. The ability to initiate degradation of a substrate that had a stem structure at its 3' end differed for the B. subtilis and Escherichia coli PNPase enzymes.
authors.affiliation: Department of Biochemistry, Mount Sinai School of Medicine of CUNY, New York 10029-6574, USA.
authors.forename: S
authors.initials: S
authors.lastname: Mitra
authors.forename: K
authors.initials: K
authors.lastname: Hue
authors.forename: D H
authors.initials: DH
authors.lastname: Bechhofer
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000378:metabolism*; D001483:Base Sequence; D004722:Endoribonucleases / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010710:Phosphates / Q000494:pharmacology; D011117:Polyribonucleotide Nucleotidyltransferase / Q000378:metabolism*; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D015183:Restriction Mapping; D043244:Ribonuclease III; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D010710:Phosphates; D012329:RNA, Bacterial; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases; D043244:Ribonuclease III; C468366:ribonuclease III, E coli