Fig. 5.

Examination of the SinR-SinI interaction. (a) Sequence alignment of the helical hook regions of SinR and SinI. Residues are colored based on sequence similarity from Clustal Omega. Stars denote the residues involved in formation of the SinR tetramer interface (Fig. 2b). These residues in SinI were mutated to the corresponding residue of SinR to generate the SinI^quad mutant. (b) Structural alignment of SinR (green) and SinI (pink) helical hooks. Left, conserved residues line the dimerization interface. Right, SinR residues necessary for tetramer formation are significantly different in SinI. (c) AUC analysis of SinR (solid black line), SinI (solid grey line), SinI^quad (grey dashed line), SinR-SinI complex (black dot-dashed line), and SinR-SinI^quad (black dashed line).