Figure 2From: A single hydrophobic cleft in the Escherichia coli processivity clamp is sufficient to support cell viability and DNA damage-induced mutagenesis in vivoSliding clamp mutations utilized in this study. (A) Positions of mutations present in β159 (G66E and G174A) are represented as yellow space filled atoms on the structure of the wild-type clamp. (B) Proposed structure of the βC/β159 heterodimer. Positions of G66E and G174A substitutions in β159 are represented as yellow space filled atoms, while residues 362-366, which are deleted from βC, are colored red. (C) Structure of the Pol IV little finger (Pol IVLF) domain in complex with the β clamp as reported by Bunting et al. [14]. Pol IVLF is in purple. Pol IVLF contacts residues E93 and L98, as well as 362-366 of the clamp; position of E93K and L98K substitutions (yellow), and Δ362-366 (red) are indicated. (D) Positions of the E93K-L98K and I272A-L273A mutations used to characterize the ability of βC to complement the temperature sensitive growth phenotype of the dnaN159 strain are shown on the presumed structure of the βC/β159 heterodimer, which bears the G66E, G174A, and Δ362-366 mutations. Figures were generated using Imol, and the coordinates for either the wild-type clamp (2POL), or the β clamp-Pol IV little finger complex (1UNN) obtained from the PDB.Back to article page