Figure 2

Rad21-Cter allows ATP hydrolysis at AS1. (a) Free-energy surfaces (in kcal mol⁻¹) for ATP hydrolysis at AS1 in the presence (left) and absence (right) of Rad21-Cter generated via QM/MM MD simulations. The plot axes represent the reaction coordinates. RC1 (bond to be formed): the distance (in Å) between the oxygen atom of the catalytic water and the phosphorous atom of the ATP molecule γ-phosphate group (distance wat-O - ATP-PG). RC2 (bond to be broken): the distance (in Å) between the phosphorous atom of the ATP molecule γ-phosphate group and the oxygen atom 3 of the ATP β-phosphate group (distance ATP-PG - ATP-O3B). Free-energy data are represented via a colour scale, from lower (blue) to higher (red) values. MEPSA minimum energy paths are shown in cyan (presence of Rad21-Cter) and red (absence of Rad21-Cter). (b) Free-energy profiles of the MEPSA minimum-energy paths. The substrate (S), transition state (TS) and product (P) locations are indicated. (c) The reference structures of S, TS and P states in the presence of Rad21-Cter are shown. The positions of the catalytic water (wat), residues Smc1A-N34 and Smc1A-E1157, magnesium ion (Mg⁺⁺), ATP γ-phosphate (ATP-PG), ADP and leaving inorganic phosphate (Pi) are indicated.