Schematic representation and distribution of putative cyanobacterial PRX. Fused domains forming a single polypeptide chain are connected by a horizontal line. The red rectangles represent the Trx_like superfamily. Elliptical shadows with different colours represent different PRX subfamilies. Yellow rectangles represent the length of overlap. Strain and domain names are as in Figure 1 and Additional file 1, respectively. Figures are not drawn to scale.