Heterologous Expression\nof Epoxomicin in <i>Escherichia\ncoli</i>

Epoxomicin is an epoxyketone proteasome inhibitor with\nsynthetic\nderivatives approved or under investigation for treatment of multiple\nmyeloma. To leverage the advantages of <i>Escherichia coli</i> as a rapidly growing and readily engineered host for the production\nof epoxomicin and analogues, we expressed codon-optimized versions\nof the epoxomicin biosynthetic genes, <i>epxD, epxE</i>,\nand <i>epxF</i>. Epoxomicin was detected, but the major\nproduct was a ketone resulting from α,β-keto acid precursor\ndecarboxylation. Epoxomicin yield was improved by altering the copy\nnumbers of each gene and creating a fusion of <i>epxE</i> and <i>epxF</i>. Our optimized system offers promise for\nefficient engineering and biosynthesis of improved epoxomicin analogues.