New dibromopyrrole alkaloids, agesamines A (1) and B (2), were obtained as an inseparable epimeric mixture from a marine sponge Agelas sp., collected in Indonesia. The planar structures were elucidated by analysis of spectroscopic data, and the absolute configuration was determined by the calculated ECD spectrum. Marine sponges contain structurally diverse metabolites with interesting biological activities. 1 In our research to discover new biologically active compounds from natural sources, an extract of the marine sponge Agelas sp., collected in Indonesia, showed cytotoxicity in HeLa cells. We here describe the

Himeic acid A, which is produced by the marine fungus Aspergillus japonicus MF275, is a specific inhibitor of the ubiquitin-activating enzyme E1 in the ubiquitin-proteasome system. To elucidate the mechanism of himeic acid biosynthesis, feeding experiments with labeled precursors have been performed. The long fatty acyl side chain attached to the pyrone ring is of polyketide origin, whereas the amide substituent is derived from leucine. These results suggest that a polyketide synthase-nonribosomal peptide synthase (PKS-NRPS) is involved in himeic acid biosynthesis. A candidate gene cluster was selected from the results of genome sequencing analysis. Disruption of the PKS-NRPS gene by Agrobacterium-mediated transformation confirms that HimA PKS-NRPS is involved in himeic acid biosynthesis. Thus, the him biosynthetic gene cluster for himeic acid in A. japonicus MF275 has been identified.

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