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Extended Data Fig. 9 | PARP2–HPF1 in open state 2. a, Model of the
disordered H3 N-terminal tail bound to the active site of the PARP2–HPF1–
nucleosome complex. The H3 tail can reach the composite active site formed
by PARP2 and HPF1 (transparent blue). b, Model of activated PARP2–HPF1
bound to nucleosome (Fig. 1a) was rigid body fitted into the cryo-EM map of
PARP2–HPF1 in open state 2 (Extended Data Fig. 3d). PARP2 and HPF1
secondary structure elements are resolved in the cryo-EM map, and the model
can be fitted as rigid body. Model is shown in blue and the cryo-EM map in
transparent blue. c, Model of PARP2–HPF1 from b is shown fitted into the cryo-
EM map. Several PARP2 and HPF1 helices are f lexible in this conformation and
are not visible in the cryo-EM map. d, NAD+ with the cryo-EM map. In this
conformation the NAD+-binding site is closed. NAD+ was modelled based on an
alignment with PDB 6BHV. e, Comparison of activated PARP2–HPF1 (violet and
magenta) and open state 2 PARP2–HPF1 (blue). Dislocation of PARP2 helices αD
and αB and HPF1 helices α7 and α8 opens a potential substrate-release pocket.
f, As in e but close-up view at the NAD+-binding site. PARP2 helices that are not
visible in the PARP2–HPF1 structure in open state 2 are shown in violet.