The gene organization of the four putative secondary metabolite gene clusters found in the Actinoplanes sp. SE50/110 genome. (A) Non-ribosomal peptide synthetase (NRPS) cluster showing high structural and sequential similarity to the SMC14 gene cluster identified on the pSCL4 megaplasmid from Streptomyces clavuligerus ATCC 27064. (B) Large polyketide synthase (PKS) gene cluster exhibiting 62-66% similarity to PKSs from various Streptomyces strains. (C) A single PKS gene with various accessory genes showing some structural similarity to a yet uncharacterized PKS gene cluster of Salinispora tropica CNB-440. (D) Putative hybrid NRPS/PKS gene cluster with NRPS genes showing high similarity (63-76%) to genes from an uncharacterized cluster of Streptomyces venezuelae ATCC 10712 whereas the PKS genes exhibit highest similarity (63-66%) to genes scattered in the Methylosinus trichosporium OB3b genome.