Problems of Studies of Specific Cell Autoregulators (On the Example of Substances Produced by Some Actinomycetes)

Khokhlov, A. S.

doi:10.1016/b978-0-08-023967-5.50030-9

Cited by 30 publications

(17 citation statements)

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“…All the known ␥-butyrolactone autoregulators, which belong to one of three types (virginiae butanolide [VB] type, possessing a 6-␣-hydroxy group [18,39]; IM-2 type, possessing a 6-␤-hydroxy group [30,36]; and A-factor type, possessing a 6-keto group [14,20] [ Fig. 1A]), possess type-specific receptor proteins that recognize the tiny structural differences among the three types of autoregulators.…”

Section: Members Of the Filamentous Gram-positive Bacterial Genusmentioning

confidence: 99%

barS1, a Gene for Biosynthesis of a γ-Butyrolactone Autoregulator, a Microbial Signaling Molecule Eliciting Antibiotic Production inStreptomycesSpecies

2002

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From Streptomyces virginiae, in which production of streptogramin antibiotic virginiamycin M 1 and S is tightly regulated by a low-molecular-weight Streptomyces hormone called virginiae butanolide (VB), which is a member of the ␥-butyrolactone autoregulators, the hormone biosynthetic gene (barS1) was cloned and characterized by heterologous expression in Escherichia coli and by gene disruption in S. virginiae. The barS1 gene (a 774-bp open reading frame encoding a 257-amino-acid protein [M r , 27,095]) is situated in the 10-kb regulator island surrounding the VB-specific receptor gene, barA. The deduced BarS1 protein is weakly homologous to ␤-ketoacyl-acyl carrier protein/coenzyme A reductase and belongs to the superfamily of short-chain alcohol dehydrogenase. The function of the BarS1 protein in VB biosynthesis was confirmed by BarS1-dependent in vitro conversion of 6-dehydro-VB-A to VB-A, the last catalytic step in VB biosynthesis. Of the four possible enantiomeric products from racemic 6-dehydro-VB-A as a substrate, only the natural enantiomer of (2R,3R,6S)-VB-A was produced by the purified recombinant BarS1 (rBarS1), indicating that rBarS1 is the stereospecific reductase recognizing (3R)-isomer as a substrate and reducing it stereospecifically to the (6S) product. In the ⌬barS1 mutant created by homologous recombination, the production of VB as well as the production of virginiamycin was lost. The production of virginiamycin by the ⌬barS1 mutant was fully recovered by the external addition of VB to the culture, which indicates that the barS1 gene is essential in the biosynthesis of the autoregulator VBs in S. virginiae and that the failure of virginiamycin production was a result of the loss of VB production.

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Section: Members Of the Filamentous Gram-positive Bacterial Genusmentioning

confidence: 99%

barS1, a Gene for Biosynthesis of a γ-Butyrolactone Autoregulator, a Microbial Signaling Molecule Eliciting Antibiotic Production inStreptomycesSpecies

2002

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“…A-factor, 2-S-isocapryloyl-3-S-hydroxymethyl-y-butyrolactone, found in Streptomyces griseus and Streptomyces bikiniensis (Khokhlov et al, 1973), is a potent autoregulating factor essential for both streptomycin biosynthesis and spore formation in these organisms (Khokhlov et al, 1973;Khokhlov, 1980;Hara & Beppu, 1982a). Furthermore, recent work from this laboratory has revealed that A-factor is also involved in streptomycin resistance in these organisms through its inducible effect on the synthesis of streptomycin-6-phosphotransferase (Hara & Beppu, 1982 b).…”

Section: Introductionmentioning

confidence: 99%

Genetic Analysis of A-factor Synthesis in Streptomyces coelicolor A3(2) and Streptomyces griseus

et al. 1983

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A-factor is a potent pleiotropic effector produced by Streptomyces griseus and is essential for streptomycin production and spore formation in this organism. Its production is widely distributed among various actinomycetes including Streptomyces coelicolor A3(2). Genetic analysis of A-factor production was carried out with S . coelicolor A3(2), and two closely linked loci for A-factor mutations (afsA and B) were identified between cysD and leuB on the chromosomal linkage map. In contrast, genetic crosses of A-factor-negative mutants of S. griseus, using a protoplast fusion technique, failed to give a fixed locus for A-factor gene(s) and suggested involvement of an extrachromosomal or transposable genetic element in A-factor synthesis in this organism. INTRODUCTIONA-factor, 2-S-isocapryloyl-3-S-hydroxymethyl-y-butyrolactone, found in Streptomyces griseus and Streptomyces bikiniensis (Khokhlov et al., 1973), is a potent autoregulating factor essential for both streptomycin biosynthesis and spore formation in these organisms (Khokhlov et al., 1973;Khokhlov, 1980; Hara & Beppu, 1982a). Furthermore, recent work from this laboratory has revealed that A-factor is also involved in streptomycin resistance in these organisms through its inducible effect on the synthesis of streptomycin-6-phosphotransferase (Hara & Beppu, 1982 b). Mutants lacking A-factor simultaneously lose streptomycin production capability, the ability to form spores and a large degree of streptomycin resistance. Exogenous supplementation of A-factor to the culture of these mutants restores all these phenotypes. A-factor-negative mutants of S . griseus and S. bikiniensis were easily obtained at high frequency by treatment with acridine dyes or by incubation at high temperature, which suggested involvement of an extrachromosomal genetic determinant in the biosynthesis of A-factor in these organisms.A-factor productivity has been found in various species of actinomycetes including Streptomyces coelicolor A3(2) (Efremenkova et al., 1979; Hara & Beppu, 1982a), but in contrast to S . griseus and S. bikiniensis, no A-factor-negative mutants of S. coelicolor A3(2) were obtained by the curing treatments. In this report, we describe genetic analyses of A-factor genes of S . coelicolor A3(2) and S . griseus, using conjugation and protoplast fusion techniques, respectively. The results clearly indicate that A-factor gene(s) of S. coelicofor A3(2) are located at a fixed position on the chromosomal linkage map, while in S . griseus, they appear to be extrachromosomal.t Present address: Fermentation Technology Laboratories, Meiji

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“…Butyrolactone autoregulators found in the genus Streptomyces are regarded as microbial hormones which, at nanomolar concentrations, control the production of secondary metabolites and morphological differentiation such as aerial mycelium formation (14,31). According to their structural differences in the C-2 side chain, 10 butyrolactone autoregulators identified to date have been classified into three types ( Fig.…”

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Butyrolactone autoregulator receptor protein (BarA) as a transcriptional regulator in Streptomyces virginiae

et al. 1997

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BarA ofButyrolactone autoregulators found in the genus Streptomyces are regarded as microbial hormones which, at nanomolar concentrations, control the production of secondary metabolites and morphological differentiation such as aerial mycelium formation (14, 31). According to their structural differences in the C-2 side chain, 10 butyrolactone autoregulators identified to date have been classified into three types ( Fig. 1): (i) the virginiae butanolide (VB) type, exemplified by VB-A to 19,29,35,36) controlling virginiamycin production, possesses a 6-␣-hydroxy group; (ii) the IM-2 type, such as IM-2 of Streptomyces sp. strain FRI-5 controlling the production of a blue pigment and nucleoside antibiotics, possesses a 6-␤-hydroxy group (21, 31, 39); and (iii) the A-factor type, such as the A-factor of Streptomyces griseus, possesses a 6-keto group (11,18,22). Although the structural differences among these autoregulators are small, producer strains show a high degree of ligand specificity toward the corresponding autoregulator type, indicating the presence of receptor proteins of strict ligand specificity (7,20,23).The individual receptor proteins for the three types of autoregulators have been isolated and characterized (24,26,34). The gene for the VB-specific receptor was cloned from Streptomyces virginiae, characterized in our laboratory, and designated the barA (butyrolactone autoregulator receptor) gene. The barA product is a 232-amino-acid protein with a size of 25,001 Da which exists as a dimer in vitro. Although the deduced amino acid sequence of BarA did not show any overall homology with other proteins except for the A-factor receptor protein (ArpA) from S. griseus (26) and the IM-2 receptor protein (FarA) from Streptomyces sp. strain FRI-5 (34), onefourth of its N terminus exhibited homology (37) with the N-terminal regions of several transcriptional repressors of prokaryotic origin, such as TcmR from Streptomyces glaucescens (5,6,8,27,33,41). These transcriptional repressors belong to the TetR family of transcriptional repressors having a helixturn-helix DNA binding motif on the N terminus (9, 17). The predicted presence of a helix-turn-helix motif in BarA leads to the speculation that BarA also binds to DNA and acts as a transcriptional repressor. However, no direct evidence for the DNA binding activity or the physiological function of BarA has been reported.In this study, using purified recombinant BarA (rBarA) overexpressed in Escherichia coli, we have tested the DNA binding activity of BarA by surface plasmon resonance (SPR) analysis and a gel-shift assay and present for the first time in vitro evidence for its DNA binding activity. The DNA region to which BarA bound was localized to the promoter region of the downstream barB gene, suggesting that BarB may be the nextstep regulator in the signal transduction pathway of VBs leading finally to virginiamycin production. In vitro and in vivo analyses of the effect of VB are also presented, demonstrating that the regulatory function of BarA is controlle...

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Problems of Studies of Specific Cell Autoregulators (On the Example of Substances Produced by Some Actinomycetes)

Cited by 30 publications

References 1 publication

barS1, a Gene for Biosynthesis of a γ-Butyrolactone Autoregulator, a Microbial Signaling Molecule Eliciting Antibiotic Production inStreptomycesSpecies

barS1, a Gene for Biosynthesis of a γ-Butyrolactone Autoregulator, a Microbial Signaling Molecule Eliciting Antibiotic Production inStreptomycesSpecies

Genetic Analysis of A-factor Synthesis in Streptomyces coelicolor A3(2) and Streptomyces griseus

Butyrolactone autoregulator receptor protein (BarA) as a transcriptional regulator in Streptomyces virginiae

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