Fig. 3.

Proposed patellazoles biosynthetic pathway. The trans-AT PKS pathway contains 14 modules, with proposed repeated use (stuttering) of module 3 (PtzA) and use of the starting module of PtzF to produce the side chain. Predictions of structures accepted by KSs by phylogenetic analysis (SI Appendix, Fig. S11) are shown above the domains, as are predications for KR stereospecificity (SI Appendix, Fig. S14 and Table S11). A, adenylation; ACP, acylcarrier protein, also denoted by a filled black circle (predicted active) or a filled gray circle (predicted inactive); AT, acyltransferase; C, condensation; Cy, condensation/cyclization; DCR, 2,4-dienoyl-CoA-reductase; DH, dehydratase; ECH, enoyl-CoA-reductase; ER, enoyl-reductase; HMGS, 3-hydroxy-3-methylglutaryl-CoA synthase; KR, ketoreductase; KS, ketosynthase; MOX, flavin monooxygenase; MT, C-methyltransferase; OMT, O-methyltransferase; OX, thiazoline oxidase; P450, cytochrome P450; TE, thioesterase.