FIG. 2.

Comparison of a 90-kb section of the herbimycin biosynthetic gene cluster with the genes responsible for geldanamycin production. PKS genes (A1, A2, and A3) and the PKS domains for both the hbm and gdm cluster are given in blue, with the modular organization indicated above each PKS gene by broad arrows. PKS tailoring genes are in green, and differences in gene organization or homology are indicated in red. “No homology” or “end of homology” indicates that these DNA regions are present but have <20% similarity; “missing in hbm” indicates that this region of DNA is absent in the herbimycin-producing gene cluster, whereas the comparable region contains the gdmF and gdmM genes in the geldanamycin producer.