FIG 2.

Locations of the six adenylation domains in the NRPS modules. TycA-A in tyrocidine synthetase (a), BacB2-A and BacC4-A in bacitracin synthetase (b), and PbtA1-A, PbtB2-A, and PbtB3-A in paenibacterin synthetase (c). All six adenylation domains are located upstream from the epimerization domains. Domain labeling is as follows: T, thiolation domain; C, condensation domain; E, epimerization domain; and Te, thioesterase domain. The three-letter code represents the adenylation domain and amino acid as its substrate (e.g., Phe represents the adenylation domain whose amino acid substrate is phenylalanine).