FIG 3.

Phylogeny derived from BEAST analyses of TyrA amino acid sequences supports an origin by lateral transfer from bacterial phyla other than cyanobacteria of the homologs in the scytonemin operon. It is shown as exemplary of the three phylogenies (AAAB loci trpE, aroB, and tyrA) supporting such an origin. Phylogenies for the other genes are found in Fig. S5 and S9. Entries in blue type correspond to homologs found within full scytonemin operons. Those marked by a blue arrow were found in remnant scytonemin operons or correspond to supernumerary homologs. Bayesian posterior probabilities (BPP) at the nodes are color coded as follows: red for BPP ≥ 0.8, pink for 0.8 ≥ BPP ≥ 0.5, and white for BPP ≤ 0.5.