A Self-defense Gene Homologous to Tetracycline Effluxing Gene Essential for Antibiotic Production in<i>Streptomyces aureofaciens</i>

Dairi, Tohru; Aisaka, Kazuo; Katsumata, Ryoichi; Hasegawa, Mamoru

doi:10.1271/bbb.59.1835

Cited by 36 publications

(18 citation statements)

References 7 publications

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“…1, 5). All nphT genes in the two plasmids are most likely transcribed as a single operon by read-through from the promoter of the replication protein in the vector pSE101 (19)(20)(21).…”

Section: Resultsmentioning

confidence: 99%

Unprecedented acetoacetyl-coenzyme A synthesizing enzyme of the thiolase superfamily involved in the mevalonate pathway

Okamura

Tanaka

Sawa

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Acetoacetyl-CoA is the precursor of 3-hydroxy-3-methylglutaryl (HMG)-CoA in the mevalonate pathway, which is essential for terpenoid backbone biosynthesis. Acetoacetyl-CoA is also the precursor of poly-β-hydroxybutyrate, a polymer belonging to the polyester class produced by microorganisms. The de novo synthesis of acetoacetyl-CoA is usually catalyzed by acetoacetyl-CoA thiolase via a thioester-dependent Claisen condensation reaction between two molecules of acetyl-CoA. Here, we report that nphT7 , found in the mevalonate pathway gene cluster from a soil-isolated Streptomyces sp. strain, encodes an unusual acetoacetyl-CoA synthesizing enzyme. The recombinant enzyme overexpressed in Escherichia coli catalyzes a single condensation of acetyl-CoA and malonyl-CoA to give acetoacetyl-CoA and CoA. Replacement of malonyl-CoA with malonyl-(acyl carrier protein) resulted in loss of the condensation activity. No acetoacetyl-CoA synthesizing activity was detected through the condensation of two molecules of acetyl-CoA. Based on these properties of NphT7, we propose to name this unusual enzyme of the thiolase superfamily acetoacetyl-CoA synthase. Coexpression of nphT7 with the HMG-CoA synthase gene and the HMG-CoA reductase gene in a heterologous host allowed 3.5-fold higher production of mevalonate than when only the HMG-CoA synthase and HMG-CoA reductase genes were expressed. This result suggests that nphT7 can be used to significantly increase the concentration of acetoacetyl-CoA in cells, eventually leading to the production of useful terpenoids and poly-β-hydroxybutyrate.

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“…1, 5). All nphT genes in the two plasmids are most likely transcribed as a single operon by read-through from the promoter of the replication protein in the vector pSE101 (19)(20)(21).…”

Section: Resultsmentioning

confidence: 99%

Unprecedented acetoacetyl-coenzyme A synthesizing enzyme of the thiolase superfamily involved in the mevalonate pathway

Okamura

Tanaka

Sawa

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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“…strain IGTS8 (12) and with the C-terminal part of SnaA from S. pristinaespiralis (7). (B) Alignment of the N-terminal region of NtaB (Ntamob) with SnaC from S. pristinaespiralis (7), ActVB of S. coelicolor (20), partial peptide from an ORF next to PheA of Bacillus stearothermophilus (Bsorf) (31), HpaC from E. coli (EcHpaC) (36), and a partial peptide from an ORF next to the tetracycline self-defense gene of S. aureofaciens (Stmorf) (11).…”

Section: Resultsmentioning

confidence: 99%

Cloning and characterization of the genes encoding nitrilotriacetate monooxygenase of Chelatobacter heintzii ATCC 29600

1996

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A 6.2-kb DNA fragment containing the genes for the nitrilotriacetate (NTA) monooxygenase of Chelatobacter heintzii ATCC 29600 was cloned and characterized by DNA sequencing and expression studies. The nucleotide sequence contained three major open reading frames (ORFs). Two of the ORFs, which were oriented divergently with an intergenic region of 307 bp, could be assigned to the NTA monooxygenase components A and B. The predicted N-terminal amino acid sequences of these ORFs were identical with those determined for the purified components. We therefore named these genes ntaA (for component A of NTA monooxygenase) and ntaB (for component B). The ntaA and ntaB genes could be expressed in Escherichia coli DH5␣, and the gene products were visualized after Western blotting (immunoblotting) and incubation with polyclonal antibodies against component A or B. By mixing overproduced NtaB from E. coli and purified component A from C. heintzii ATCC 29600, reconstitution of a functional NTA monooxygenase complex was possible. The deduced gene product of ntaA showed only significant homology to SoxA (involved in dibenzothiophene degradation) and to SnaA (involved in pristamycin synthesis); that of ntaB shared weak homologies in one domain with other NADH:flavine mononucleotide oxidoreductases. These homologies provide no conclusive answer as to the possible evolutionary origin of the NTA monooxygenase. The deduced gene product of the third ORF (ORF1) had homology in the N-terminal region with the GntR class of bacterial regulator proteins and therefore may encode a regulator protein, possibly involved in regulation of ntaA and ntaB expression.

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“…(Ohnuki et al, 1985;Dairy et al, 1995). Group 2 and 3 are characterized by 14 membrane-spanning α-helices (Levy, 1992;Guay et al, 1993).…”

Section: Active Effluxmentioning

confidence: 99%

Tetracyclines in veterinary medicine and bacterial resistance to them

Michalova¹,

PNovotna²,

Schlegelová³

2004

Vet. Med.

119

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Since their discovery in 1945, tetracyclines have been used extensively in the therapy and prophylaxis of infectious diseases and as growth promoters. These wide applications have led to the equally fast spread of tetracycline resistant strains of gram-positive and gram-negative bacterial genera, including strains belonging to pathogenic as well as nonpathogenic species. Nonpathogenic bacteria could act as a reservoir of resistance determinants, which can be disseminated by horizontal transfer into pathogens. More than thirty different tetracycline resistance genes have been characterized. They encode two major mechanisms of resistance: 1 -active efflux of the antibiotic, and 2 -protection of ribosomes. Further mechanisms of tetracycline resistance include enzymatic inactivation of antibiotic, permeability barriers, mutations or multidrug transporter systems. Effective horizontal spread is favoured by the location of tetracycline resistance genes on mobile genetic elements such as plasmids and transposons. Their exchange, enhanced by the use of tetracyclines, is observed between bacteria of the same or different species and genera as well. Thus, questions of reevaluating and global reducing of tetracyclines in human and animal healthcare and food production are extensively discussed.

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A Self-defense Gene Homologous to Tetracycline Effluxing Gene Essential for Antibiotic Production inStreptomyces aureofaciens

Cited by 36 publications

References 7 publications

Unprecedented acetoacetyl-coenzyme A synthesizing enzyme of the thiolase superfamily involved in the mevalonate pathway

Unprecedented acetoacetyl-coenzyme A synthesizing enzyme of the thiolase superfamily involved in the mevalonate pathway

Cloning and characterization of the genes encoding nitrilotriacetate monooxygenase of Chelatobacter heintzii ATCC 29600

Tetracyclines in veterinary medicine and bacterial resistance to them

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