Sequence network
A threshold of 60% similarity was used to construct protein sequence networks for LED superfamilies 11 and 13 whose members originated from Proteobacteria only (Figure 2 ). Two disconnected sequence networks emerged: a network of 127 representative sequences of superfamily 11, which contains the GX-type PURases PueA andPueB from Pseudomonas chlororaphis , and a network of fifteen representative sequences of superfamily 13, which contains the GGGX-type the PURase PudA from Delftia acidovorans . In both superfamilies 11 and 13, the sequences originated mainly from Gammaproteobacteria, with the genus Pseudomonas being most frequently annotated in superfamily 11.