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. 2017 Jan 30;8:14011. doi: 10.1038/ncomms14011

Figure 5. Alleles of smc6 and sulphate-ion coordinating arginine-pairs.

Figure 5

(a, left) Molecular secondary structure cartoon, highlighting the relative positions of the Arg706 and Gly551 residues (coloured green) mutated in the S. pombe smc6-X and smc6-T2 alleles, respectively. (a, middle) Alternative view of the Gly551 residue, showing its proximity to Arg706. (a, right) Mutation of Gly551 to any residue would cause disruption of the protein fold, due to the Cα position being conformationally constrained to point into the core of the protein, rather than out to solvent. Potential hydrogen bonds are indicated by the orange dashed-lines. See associated key for additional details. (b) DNA damage sensitivity of S. pombe strains containing the single-point mutant F528A. Dose and type of treatment is as indicated. (b) Spot tests showing HU and MMS sensitivity of Smc6-F528A strain. (c) Analytical size exclusion chromatograms for wild-type or the indicated mutant forms of Smc5/6-hinge. ‘Truncated-hinge' constructs were used in these experiments (see Supplementary Table 1) as we found that elution volume differences were more pronounced than in equivalent experiments with extended hinges; this is consistent with a dominant effect of the long flexible ‘arms' on hydrodynamic radius, masking subtler changes in hinge conformation. The elution peak positions of a molecular mass calibration are also shown for the G551R (smc6-T2) chromatogram. (d) Molecular surface representations, coloured by electrostatic potential. (Left) view of the North interface, (Middle) top down view, (Right) view of the South interface. Bound sulphate ions are shown in ball-and-stick representation, and consecutively labelled S1 – S3. (e) Molecular secondary structure cartoon highlighting the position of the Smc5 Arg587/Arg619 and Arg609/Arg615 pairs which each coordinate a sulphate ion. See associated key for details. (f) DNA damage sensitivity of S. pombe strains containing the charge-reversal mutants R587E/R619E and R609E/R615E. Dose and type of treatment is as indicated.