Domain organization of the NRPS modules in griseobactin biosynthesis compared to those in bacillibactin and enterobactin biosynthesis. A, adenylation domain; ACP, aryl carrier protein; C, condensation domain; PCP, peptidyl carrier protein/thiolation domain; TE, thioesterase domain; IC, isochorismatase. The specificities of the adenylation domains are given in parentheses.