CMTR1 methyltransferase stimulates DHX15 helicase activity. CMTR1 methyltransferase stimulates DHX15 helicase activity. (A) 100 nM His6-DHX15 was incubated with α32P-ATP in the absence or presence of 1 μg HeLa cell RNA for the time indicated. The ADP generated was resolved by TLC and detected by phosphoimager throughout the figure unless indicated. (B) Average percentage of ATP hydrolysis and standard deviation are plotted for two experiments. (C) 100 nM His6-DHX15 was incubated with α32P-ATP and 1 μg RNA or nM CMTR1 indicated for 30 min. ATP hydrolysis was detected. (D) Average percentage ATP hydrolysis and standard deviation are plotted for three independent experiments. t test was performed relative to DHX15 alone. ***P-value < 0.005. (E) 100 nM His6-DHX15 alone or 100 nM His6-DHX15, 1 μg HeLa RNA, and indicated concentration of CMTR1 were incubated with α32P-ATP for 30 min. Percentage of ATP hydrolysis is plotted over time. (F) 100 nM DHX15 was incubated with 10 μM SAM, 1 μg HeLa RNA, and 100 nM CMTR1 as indicated for 30 min. Percentage of ATP hydrolysis is plotted. (G) RNA-32P-DNA duplex was incubated with with1mM ATP and indicated nM His6-DHX15 and CMTR1. After 30 min, samples were resolved by native PAGE and visualized using a phosphorimager. “Unwound” indicates single stranded 32P-DNA oligonucleotide. ∆T is the 95°C denatured substrate. (H) Average percentages of unwound substrate and standard deviations are presented for three independent experiments. Francisco Inesta-Vaquera et al. LSA 2018;1:e201800092 © 2018 Inesta-Vaquera et al.