The pathway-specific regulatory genes, tei15* and tei16*, are the master switches of teicoplanin production in Actinoplanes teichomyceticus.

Pathogenic antibiotic-resistant bacteria are an unprecedented threat to health care worldwide. The range of antibiotics active against these bacteria is narrow; it includes teicoplanin, a "last resort" drug, which is produced by the filamentous actinomycete Actinoplanes teichomyceticus. In this report, we determine the functions of tei15* and tei16*, pathway-specific regulatory genes that code for StrR- and LuxR-type transcriptional factors, respectively. The products of these genes are master switches of teicoplanin biosynthesis, since their inactivation completely abolished antibiotic production. We show that Tei15* positively regulates the transcription of at least 17 genes in the cluster, whereas the targets of Tei16* still remain unknown. Integration of tei15* or tei16* under the control of the aminoglycoside resistance gene aac(3)IV promoter into attBϕC31 site of the A. teichomyceticus chromosome increased teicoplanin productivity to nearly 1 g/L in TM1 industrial medium. The expression of these genes from the moderate copy number episomal vector pKC1139 led to 3-4 g/L teicoplanin, while under the same conditions, wild type produced approximately 100 mg/L. This shows that a significant increase in teicoplanin production can be achieved by a single step of genetic manipulation of the wild-type strain by increasing the expression of the tei regulatory genes. This confirms that natural product yields can be increased using rational engineering once suitable genetic tools have been developed. We propose that this new technology for teicoplanin overproduction might now be transferred to industrial mutants of A. teichomyceticus.

Evaluation of heterologous promoters for genetic analysis of Actinoplanes teichomyceticus--Producer of teicoplanin, drug of last defense.

Actinoplanes teichomyceticus is the only known producer of the valuable glycopeptide antibiotic teicoplanin. Random mutagenesis and selection were extensively applied to teicoplanin producers, while the gene engineering methods were not used, because of the paucity of genetic tools for A. teichomyceticus. Particularly, availability of promoters of different strength that are functional in Actinoplanes would be very useful for overexpression of beneficial genes. Here we report the use of a glucuronidase reporter system (gusA) for studying transcriptional activity in A. teichomyceticus and describe the behavior of a set of heterologous promoters in this strain. We reveal several elements that exceed in their strength the well-established Streptomyces promoter ermEp, underscoring the utility of the gusA reporter for Actinoplanes sp. Remarkable overproduction of teicoplanin was achieved by constructing strains carrying additional copies of the regulatory gene tcp28 under the control of one of the two most active promoters, moeE5p and actp, discovered in this study.

An ABC transporter encoding gene lndW confers resistance to landomycin E.

Streptomyces globisporus 1912 produces a polyketide antibiotic landomycin E (LaE), which possesses anticancer activity. A 1.8 kb DNA fragment at the end of landomycin E biosynthetic gene cluster was sequenced. DNA sequence analysis of this fragment identified one complete open reading frame, designated lndW. The deduced sequence of lndW gene product revealed significant similarity to the ATP-binding domains of the ABC (ATP-binding protein cassette) superfamily of transport-related proteins. Knockout of lndW had no significant effect on resistance to LaE and its production. The expression of lndW in S. globisporus 1912 was proven via transcriptional fusion of lndW promoter to EGFP (enhanced green fluorescent protein). Overexpression of lndW in S. lividans TK24 conferred resistance to LaE. The mechanism of lndW function in LaE biosynthesis is discussed.