An ABC transporter involved in the control of streptomycin production inStreptomyces griseus

Abstract

We screened for a gene that inhibits streptomycin production in Streptomyces griseus when it is introduced on a high-copy-number plasmid pIJ702, and obtained a plasmid pKM545. The introduction of pKM545 abolished streptomycin production on all media tested including YMP-sugar and Nutrient broth. S1 protection analysis demonstrated that the introduction of this plasmid downregulated the transcriptional activity of the promoter preceding strR, the pathway-specific transcriptional regulator for streptomycin biosynthesis. The 2.8-kb BamHI fragment cloned onto pKM545 contained two coding sequences SGR_5442 and 5443. These coding sequences and the two downstream ones (SGR_5444 and 5445) constituted a possible operon structure designated to be rspABCD (regulation of streptomycin production). RspB and RspC exhibited a marked similarity with an ATP-binding domain and a membrane-associating domain of an ABC-2 type transporter, respectively, suggesting that the Rsp proteins comprise a membrane exporter. The gene cluster consisting of the rsp operon and the upstream divergent small coding sequence (SGR_5441) was widely distributed to Streptomyces genome. An rspB mutant of S. griseus produced 3-fold streptomycin of the parental strain in YMP liquid medium. The evidence implies that the Rsp translocator is involved in the export of a substance that specifies the expression level of streptomycin biosynthesis genes in S. griseus.

Characterization of the Noncanonical Regulatory and Transporter Genes in Atratumycin Biosynthesis and Production in a Heterologous Host

“…The essential synthetic and regulatory genes of most Streptomyces BGCs contain transporter genes belonging to the ATP-binding cassette transporter family [19,20]. Currently, the known ABC transporters are classified into three categories according to their different structural features; these categories are Type I, Type II and Type III [21].…”

Regulation of multidrug efflux pumps by TetR family transcriptional repressor negatively affects secondary metabolism inStreptomyces coelicolorA3(2)

“…This includes disruption of actR- encoding TFR, leading to overexpression of actAB , an RND-type transporter, and results in increased actinorhodin biosynthesis in S. coelicolor A3(2) (54). While most studies have focused on the positive effect on the SM production, few studies state that expression of ABC transporters leads to reduced production of SMs; for example, streptomycin production is decreased upon overexpression of the ABC-2 type transporter RspBC in Streptomyces griseus (55). However, elucidating the uncharacterized orphan systems that negatively affect SM production is important for a deeper understanding of how the SM production system participates in the whole-cell system.…”