Fig. 1: The crystal structure of AcrIF24, a dimer that inhibits the type I-F CRISPR-Cas system.
a AcrIF24 but not AcrIF24ΔMD inhibits the in vitro cleavage activity of the type I-F CRISPR-Cas system. Reactions were performed with 0.32 μM Csy complex, 0.16 μM Cas2/3, and 0.04 μM 54-bp dsDNA (5′-FAM in the non-target DNA strand, NTS). AcrIF24 or AcrIF24ΔMD was added with concentrations of 0.16, 0.32, and 0.64 μM following the order indicated by the black triangles. Fraction DNA cleavage was calculated as mentioned in the Methods section. Data are presented as mean values ± SD; n = 3. Two-sided t test was performed. The “*“ indicates that there is a significant difference between the quantitative data (P < 0.05). *P = 0.0199, 0.0018, 0.0008 (left to right). b The crystal structure of AcrIF24 is shown in the cartoon model, together with its schematic illustration. The NTD and CTD are colored in yellow and cyan, respectively. The HTH motif is colored in orange. The unmodelled MD is indicated by the dashed line and colored hot pink in the schematic illustration. c Static light scattering (SLS) studies of AcrIF24 and AcrIF24ΔMD. The calculated molecular weights of the main peaks of the two profiles are shown above the peaks. d The AcrIF24ΔMD dimer is shown in the cartoon and surface model. Two perpendicular views are shown. e Structural superimposition between AcrIF24CTD and the clp gene regulator ClgR from Corynebacterium glutamicum (PDB: 3F51). AcrIF24CTD and ClgR are colored in cyan and marine, respectively. Two perpendicular views are shown.
