Comparison of two 9-membered enediyne (C-1027 and NCS) biosynthetic gene clusters around the genes of enediyne PKS ( sgcE and ncsE ) (A) and amino acid sequence alignment for SgcR3 (B). A, Open reading frames are indicated by arrows. Homologue genes of regulatory sgcR1, sgcR2 and sgcR3 identified by sequence analysis are shown in grey or black. Genes outside of the clusters are marked by broken line arrows. B, The multialignment of S. globisporus C-1027 SgcR3, S. carzinostaticus ATCC 15944 NscR7 and S. fradiae TylR. Identical residues are highlighted in black and similar residues are shaded. The numbers indicate amino acid positions.