Figure 6.

The DNA Trajectory into the Cohesin Ring

(A) Schematic of the DPC-MS workflow. See the main text for details.

(B) A representative mass spectrum of a peptide containing a diazirine mass tag. The diagnostic 159u ion is highlighted.

(C) DNA crosslinks of a 125-bp linear DNA in the gripping state, shown on the surface of the hybrid model (light blue), compared with crosslinks observed with a 3-kb circular plasmid DNA (medium blue). Crosslinks in common are shown in dark blue.

(D) DNA crosslinks in the initial DNA binding state (light blue) are compared with those in the gripping state (medium blue); those in common are shown in dark blue. Arrowheads highlight crosslinks along the SMC coiled coils and hinge.

(E) A model of the DNA trajectory from initial binding toward the gripping state, based on the observed DNA contacts.

(F) DNA gripping experiment using head-head crosslinked cohesin. Psm1-SNAP Psm3-CLIP cohesin was treated with SC-Cy5 to close the head gate before the gripping reaction. DNA-bound proteins were analyzed by immunoblotting and in-gel Cy5 detection.

See Figure S6 for additional DPC-MS results.