Genomic region associated with scytonemin biosynthesis in several strains of cyanobacteria. (A) Genomic region in N. punctiforme, Anabaena, Nodularia, and Lyngbya (not drawn to scale). Arrows represent the transcriptional orientation of the genes, which are filled in according to the functional category as follows: red, regulatory proteins; yellow, scytonemin core genes; pink, aromatic amino acid biosynthetic genes; black, orthologs to the five-gene satellite cluster in N. punctiforme; white, genes without homologues among the strains studied; all other colors represent orthologs. Hash marks delimit the two gene clusters in N. punctiforme and carats connect adjacent genes. The vertical alignments of the genes facilitate the visual representation of orthologous proteins, with one exception; the white gene positioned in the Nodularia yellow gene cluster causes a shift in the vertical alignment of the corresponding orthologous genes which is corrected at the position of the "glycosyltransferase". Orthologues to the five-gene satellite cluster from N. punctiforme are specified with a star and dashed lines facilitate their alignment. (B) Genomic region associated with scytonemin biosynthesis of Chlorogloeopsis, vertically aligned to match N. punctiforme in (A). An ortholog to the last gene in the N. punctiforme cluster has not been identified in Chlorogloeopsis and tyrP does not appear to be integrated within the gene cluster, although it is present in the genome. Genes that are not continuously linked are shown by the insertion of hash marks.