Figure 4: The heterodimer interfaces of Smc5/6 are highly divergent.
From: Specialized interfaces of Smc5/6 control hinge stability and DNA association
(a) Schematic secondary structure molecular cartoon, highlighting both the 8-stranded β-sheet and the position of conserved glycine residues, found at the core of each hinge interface in murine cohesin (Smc1/3), murine condensin (Smc2/4) and TmSmc. (b) Amino acid sequence alignment highlighting the conserved set of glycine residues found in the last two β-strands of Subdomain II of SMC-family hinge-domains. Smc6 contains a partial match to the consensus sequence, but Smc5 does not. (c) Molecular cartoon, as in a but for the North and South interfaces of Smc5/6. The loops connecting the last three β-strands of Subdomain II are additionally highlighted, and labelled consecutively from A to C. Amino acids at the start and end of the β-strands that pair to form each interface are numbered. (d) Assessing hinge stability by co-expression/co-purification assay. His-tagged Smc5-hinge was co-expressed with StrepII-tagged Smc6-hinge in E. coli. After lysis, and clarification, the soluble fraction was passed through an IMAC column, capturing the Smc5-hinge. After successive washes, to remove any unbound material, the amount of co-purified Smc6-hinge was assessed by western blot. WT=wild-type, 5-Y612A=Smc5-hinge containing the Loop C mutation, 6-Mut=Smc6-hinge containing S692E, G694K and S696E mutations.
