ABC transporter genes from Streptomyces ghanaensis moenomycin biosynthetic gene cluster: roles in antibiotic production and export.

Streptomyces ghanaensis ATCC14672 produces antibiotic moenomycin A (MmA), which possesses strong antibacterial activity. The genetic control of MmA biosynthesis has been recently elucidated; nevertheless, little is known about the roles of two pairs of genes, moeX5moeP5 and moeD5moeJ5, coding for ATP-dependent transporter systems. Here we report that both gene pairs form transcriptional units actively expressed during MmA production phase. Streptomyces ghanaensis mutants deficient in either (one) or both transporter systems are characterized by a decreased ability to produce moenomycins, and the ΔmoeP5moeX5 mutant exported less moenomycins. However, even the quadruple S. ghanaensis mutant (ΔmoeD5moeJ5 + ΔmoeX5moeP5) remains able to extrude significant amounts of moenomycin. Similar results were observed under conditions of heterologous expression of moe cluster. Transporter genes other than those located in moe cluster are likely to participate in moenomycin efflux.