Figure 3

The relative proportions of amino acids incorporated into the X and Z position. The relative proportions of amino acids incorporated into the X and Z position of the microcystins produced by the strains included in this study as determined by LC-MS. (a) The amino acids present at the X position in microcystins. These amino acids are recognized and activated by the McyB1 adenylation domain. (b) The amino acids present at the Z position in microcystins. These amino acids are recognized and activated by the McyC adenylation domain. The structures and percentages of individual microcystins produced by the 10 strains of cyanobacteria included in this study are given in the supplementary information section (see additional file 1).