Fengycin, a lipopeptidic antibiotic, is synthesized nonribosomally by five fengycin synthetases (FenC, FenD, FenE, FenA, and FenB) in Bacillus subtilis F29-3. This work demonstrates that these fengycin synthetases interlock to form a chain, which coils into a 14.5-nm structure. In this chain, fengycin synthetases are linked in the order FenC-FenD-FenE-FenA-FenB by interactions between the C-terminal region of an upstream enzyme and the N-terminal region of its downstream partner enzyme, with their amino acid activation modules arranged colinearly with the amino acids in fengycin. This work also reveals that fengycin is synthesized on this fengycin synthetase chain, explaining how fengycin is synthesized efficiently and accurately. The results from this investigation demonstrate that forming a peptide synthetase complex is crucial to nonribosomal peptide synthesis.