Genes and proteins involved in the biosynthesis of benzodiazepines by microorganisms, including the genes and proteins forming the biosynthetic loci for the benzodiazepine anthramycin from Streptomyces refuineus subsp. thermotolerans including non-ribosomal peptide synthetases (NRPS). The genes and proteins allow direct manipulation of benzodiazepines and related chemical structures via chemical engineering of the enzymes involved in the biosynthesis of anthramycin.