FIG 5.

Recombination in the pathway generates many different functional classes of cyanobactin natural products. (A) Precursor peptide sequence alignments show that the leader peptide portion is nearly constant. At bottom, consensus (Con) and alternative substitutions (Alt) are shown. Important residues for recognition sequences I, II, and III are shown in yellow, blue, and gray, respectively. Hypervariable core peptide sequences are underlined in red. Note that each precursor encodes 2 or 3 core peptides. Total consensus and mutations for each position in the core peptide are shown in the box at right. (B) Pathway comparison in variable regions using tblastx. This represents an informative subset of alignments from the sequences shown in Fig. 4. (C) Cyanobactin structures synthesized by various pathways. Functional groups are indicated by the same colors as found in gene regions shown in panel B. Genetic changes shown in panels A and B are responsible for the resulting chemical differences.