Fig. 6. Extent of histone ribosylation in response to DNA damage correlates with the cellular concentration of TbSIR2RT1. The results of TAU gel analysis of histone ribosylation in nuclei from trypanosomes overexpressing TbSIR2RP1 and TbSIR2RP1H142Y (A) and from TbSIR2RP1 knocked-down cells (B). Histones were purified from nuclei treated for 1 h with MMS and [32P]NAD in the presence of 5 mM 3-aminobenzamide. The bottom panel shows the autoradiograph of the gel. (C) The localization of TbSIR2RP1 in cells with damaged DNA. Procyclic forms incubated in 0.001% MMS for 12 h were subjected to IF and FISH with anti-TbSIR2RP1 antibodies and telomeric probes, respectively.