Cyanobactin synthetase gene clusters in cyanobacteria. (a) The conserved cyanobactin protease genes, which can be detected using the primers designed in this work, are shaded. The peptide product of the gene cluster is presented in parentheses under the producer organism. (b) The primers cysF and cysR are aligned with cyanobactin synthetase gene sequences from seven cyanobacteria: Prochloron didemni (patA [AY986476]), Trichodesmium erythraeum IMS101 (triH [CP000393]), Lyngbya aestuarii CCY9616 (lynA [AAVU01000047]), Anabaena sp. 90 (unpublished), Nodularia spumigena CCY9414 (AAVW01000072.1), Microcystis aeruginosa NIES298 (mcaA [AM774406]), and Nostoc spongiaeforme subsp. tenue (tenA [EU290741]).