Journal: Nucleic Acids Research
Article Title: Multipronged regulatory functions of a novel endonuclease (TieA) from Helicobacter pylori
Figure Lengend Snippet: ( A ) Binding of TieA to dsDNA: electrophoretic mobility shift assays were carried out by incubating different concentrations of TieA (0.1, 0.5, 1 and 2 μg) with 0.5 nM 32 P-labeled DNA substrates. Samples were subjected to electrophoresis on native PAGE and visualized by autoradiography as mentioned in materials and methods section. ( B ) TieA binds to DNA non-specifically: electrophoretic mobility shift assays were carried out by incubating 1 μg of TieA with mutated oligos 1–5 (see Supplementary Table S1). ( C ) Nuclease activity of TieA: different concentrations of TieA (0.01, 0.1, 0.2, 0.5, 1 and 2 μg corresponding to lanes 7-12, respectively) were incubated with 1 μg of pUC19 DNA for 1 h at 37 °C. The reaction was stopped by addition of 10 mM EDTA and samples were deprotonized by adding proteinase K (10 μg/sample) in presence of 0.05% SDS for 15 min at 65°C. The digested products were separated on 1.2% agarose gel. Rv3131 (0.5 μg) was used as a negative control in lane 6. MboII (1 unit/reaction) and DNase I (1 unit/reaction) served as positive controls in lanes 3 and 5, respectively. Lane 4 represents heat inactivated TieA. ( D ) TieA cleaves both pUC19 (circular) and Lambda DNA (linear): pUC19 and Lambda DNA were incubated with TieA (lanes 5, 6, 14 and 15) for 1 h at 37°C and processed as described above. MboII (lanes 3 and 12) and DNase I (lanes 4 and 13) were used as positive controls. Rv3131 protein was used as a negative control (lanes 7 and 16). Ca 2+ –Mg 2+ dependent nuclease activity of TieA was confirmed by pre-incubating pUC19/Lambda DNA with either SDS (0.05%) or EDTA (10 mM) for 10 min (lanes 8, 9, 17 and 18) and later 1 μg of TieA was added and further processed as described above. Data are representative of three independent experiments. HI: heat inactivated.
Article Snippet: TieA showed a non-specific endonuclease activity similar to DNase I as it cleaved both circular pUC19 and linearized lambda DNA, whereas Rv3131 (lane 6) as well as heat-inactivated TieA (lane 4) did not show any detectable DNA cleavage activity (Figure ).
Techniques: Binding Assay, Electrophoretic Mobility Shift Assay, Labeling, Electrophoresis, Clear Native PAGE, Autoradiography, Activity Assay, Incubation, Agarose Gel Electrophoresis, Negative Control, Lambda DNA Preparation