Fig. 5

Nucleotide alignment of anatoxin-a clusters from Cyanobacteria. anaA-G and anaI are all conserved in Anabaena sp. WA102 and Anabaena sp. AL93, though anaH is missing from both. The 5’ region of anaB and upstream promoter region is triplicated in Anabaena sp. WA102. The anatoxin-a cluster from Anabaena sp. WA102 is most similar to that from Anabaena sp. 37. The three Anabaena strains share a gene of unknown function downstream of anaG (colored pink). The anaG genes differ in size, correlated with different variants of anatoxin-a. Shorter variants of AnaG omit or truncate a putative methyl transferase domain. The anaF and anaG genes share a region of 86 % nucleotide identity that is likely a homologous protein domain. Anabaena sp. WA102 and AL93 encode two of the shortest anaG genes and produce anatoxin-a, Cylindrospermum sp. PCC 7417 produces dihydroanatoxin-a (likely due to the unique gene Cylst 6226), and Oscillatoria sp. PCC 6506 primarily produces homoanatoxin-a