FIG. 6.

SARS-CoV nsp13 has RNA 5′-triphosphatase activity. 5′-γ-³²P-labeled RNA was prepared as described in Materials and Methods and incubated with MBP-nsp13 or MBP-nsp13_KA. The reaction products were separated by thin-layer chromatography (A) and polyacrylamide gel electrophoresis (B) and visualized by autoradiography. (A) Lane 1, [γ-³²P]GTP without protein; lane 2, [γ-³²P]GTP and MBP-nsp13 (GTPase activity); lane 3, 5′-γ-³²P-labeled RNA without protein; lane 4, 5′-γ-³²P-labeled RNA and MBP-nsp13; lane 5, 5′-γ-³²P-labeled RNA and MBP-nsp13_KA. (B) Lane 1, [γ-³²P]GTP without protein; lane 2, [γ-³²P]GTP and MBP-nsp13 (GTPase activity); lane 3, 5′-γ-³²P-labeled RNA without protein; lanes 4, 5, and 6, 5′-γ-³²P-labeled RNA and MBP-nsp13. Reactions were terminated by the addition of EDTA after 10 min (lane 4), 30 min (lane 5), and 60 min (lanes 2 and 6).