Fig. 3: The mechanism of ssDNA substrate engagement by SsdA.

a Close-up view of the SsdA-ssDNA interaction, with hydrogen bonds and salt bridges indicated by yellow dashed lines. An orange dashed line indicates an aromatic stacking interaction between Tyr334 and +1 G. b An orthogonal view looking down the narrow DNA-binding cleft, with the molecular surface of the protein colored according to electrostatic potential (blue: positive, red: negative).