• Journal of Microbiology and Biotechnology
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• v.18 no.4
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• pp.658-662
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• 2008

Effects of pH shock on the secretion system of S. coelicolor A3(2) have been investigated at a transcriptional level by using DNA microarrays. Actinorhodin secretion was observed to be highly enhanced when an acidic-pH shock was applied to surface grown cultures of S. coelicolor A3(2). In this culture, a gene of actVA-orf1 encoding a putative efflux pump or transporter protein for actinorhodin was strongly upregulated. A major number of efflux pumps for other metabolites and a major number of secretion proteins for protein secretion were also observed to be upregulated with pH shock. The secretion of actinorhodin was observed to be remarkably enhanced in liquid culture as well.

• Journal of Microbiology
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• v.35 no.4
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• pp.271-276
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• 1997

We isolated phenotypic suppressors of an absB (antibiotics synthesis suppression) strain. In the absB colonies, all four antibiotics including two pigmented antibiotics were blocked so that no pigmentation could be found. We assumed that in the colonies with the wuppressive(or reversive) mutation, both pigmentation would be restored so that the strains with suppressive mutation could be cisually detected. Harvested absB spores were treated with chemical mutagen along with electric shock, and were spread on specially fromulated minimal medium plates. The pigmented colonies were isolated from the unpigmented majorities. In one candidate strain, the restoration and significant overproduction of actinorhodin and undecylprodigiosin were recognized. In three other candidate strains, the overproduction of actinorhodin and restoraion of undecylprodigiosin were observed. The production of the two unpigmented antibiotics (CDA and methylenomycin) were visualized in the tested candidate strains. The strains with wuppressive mutations would be very useful in dlucidating the regulation network of antiviotics synthesis and overproduction of the antibiotics.

• Journal of Microbiology
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• v.40 no.1
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• pp.43-50
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• 2002

A cluster of genes encoding the pyruvate dehydrogenase complex (PDC) of Streptomyces seoulensis, a Gram-positive bacterium, was cloned and sequenced. The genes of S. seoulensis consist of four open reading frames. The first gene, lpd, which encodes a lipoamide dehydrogenase, is followed by pdhB encoding a dihydrolipoamide acetyltransferase (E2p), pdhR, a regulatory gene, and pdhA encoding a pyruvate dehydrogenase component (Elp). Elp had an unusual homodimeric subunit, which has been known only in Gram-negative bacteria S. seoulensis E2p contains two lipoyl domains like those of humans and Streptomyces faecalis. The pdhR gene appears to be clustered with the structural genes of S. seoulensis PDC. The PdhR-overexpressed S. seoulensis howed growth retardation and the decrease of Elp, indicating that PdhR regulates the function of PDC by repressing the expression of Elp. A strain of Streptomyces licidans overexpressing S. seoulensis PdhR showed a significant decreasein the level of actinorhodin, implying a regulatory role for Streptomyces PDC in antibiotic biosynthesis.

• Journal of Microbiology and Biotechnology
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• v.21 no.12
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• pp.1294-1298
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• 2011

A metK gene encoding S-adenosyl-L-methionine synthetase was cloned from the non-Streptomyces actinomycetes, Actinoplanes teichomyceticus ATCC31121. In order to evaluate the effect of the metK expression on antibiotic production in actinomycetes, an expression vector harboring the metK gene was constructed and introduced into Streptomyces lividans TK24 and A. teichomyceticus, and the antibiotic production of the exconjugants was assessed. As a result, it was determined that the expression of metK induced 17-fold and 2.2-fold increases in actinorhodin production from S. lividans TK24 and teicoplanin production from A. teichomyceticus, respectively, compared with the control strains.

• Proceedings of the Microbiological Society of Korea Conference
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• 1997.04a
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• pp.55.2-55.2
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• 1997

• Proceedings of the Zoological Society Korea Conference
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• 1994.10a
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• pp.209.2-209
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• 1994

No Abstract, See Full Text

• Journal of Microbiology and Biotechnology
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• v.16 no.6
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• pp.927-932
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• 2006

S-Adenosylmethionine (SAM) is a ubiquitous biomolecule serving mainly as a methyl donor. Our recent studies revealed that SAM controls antibiotic production in Streptomyces. In this study, the functional mode of SAM was studied in S. coelicolor and S. antibioticus ATCC11891, employing S-adenosylhomocysteine (SAH), a methylation reaction product of SAM. Actinorhodin biosynthesis did not require SAM as a methyl donor, whereas SAH enhanced the actinorhodin biosynthesis up to the level comparable to SAM, and the most effective concentration of SAH was higher than that of SAM. In the case of oleandomycin that requires SAM for its biosynthesis, both SAM and SAH at the concentration as low as 100 mM showed comparable efficacy in enhancing the production; SAM at 1 mM concentration additionally stimulated to give a 5-fold enhancement of oleandomycin production. In vitro autophosphorylation of protein kinase AfsK was found to be activated by both SAM and SAH, as well as other structurally related compounds. Our studies demonstrate that SAM regulates antibiotic biosynthesis in a mode independent of its role as a methyl donor and suggest that SAM acts directly as an intracellular signaling molecule for Streptomyces.

• Journal of Microbiology
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• v.39 no.4
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• pp.305-313
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• 2001

The spr D gene encoding Strptomyces griseus protease D(SGPD); a chymotrypsin-like proteae, was cloned from Strptomyces griseus IFO13350 and sequence. Most of the amino-acid sequence deduced from the nucleotide sequence is idential to that Strptomyces griseus IMRU3499 except that one amino acid has been deleted and Trp 369 has been substituted into Cys369 in the SGPD from S. griseus IFO13350 without affecting the protease activity. The spr D gene was overexpressed in Streptomyce liv-idans TK24 as a heterologous host. Various media with different compositions were also used to max-imize the productivity of SGPD inthe heterologous host. The SGPD productivity was best when the transformant S. lividans TK24 was cultivated in R2YE medium. The relative chymotrypsin activity of the culture broth measured with an artificial chromogenic substrate, N-scuccinyl-ala-ala-pro-phe-p-nitroanilide, was 16 units/ml. A high level of SGPD was also produced in YEME and SAAM medial but it was relatively lower that in R2YE medium and negligible amounts of SGPD were produced in GYE, GAE and Benedict media. The growth of S. lividans reacted the maximum level of cell mass at days 3 and 4 of the culture, but SGPD production started in the stationary phase of cell growth and kept increase in till the 10$^{th}$ day of culture in R2YE and YEME medium, but in GYE media the productivity reached maximum level at 8days of cultivation. The introduction of the spr D gene into S. lividans TK24 triggered biosyntheis of the pigmented antibiotic , actinorhodin, which implies some protease may paly a very improtant role in secondary-metabolite formation in sStreptomyces.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.974-974
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• 2005

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.819-822
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• 2003

Polyketides are an extensive class of secondary metabolites with diverse molecular structures and biological activities. A plasmid-based minimal polyketide synthase (PKS) expression cassette was constructed using a subset of actinorhodin (act) biosynthetic genes (actI-orfl, actI-orf2, actI-orf3, actIII, actⅦ, and actIV) from Streptomyces coelicolor, which specify the construction of an orange-fluorescent anthraquinone product aloesaponarin II, a type II polyketide compound derived from one acetyl coenzyme A and 7 malonyl coenzyme A extender units. This system was designed as an indicator pathway in S. parvulus to generate a hybrid type II polyketide compound via gene-specific replacement. The act ${\beta}-ketoacyl$ synthase unit (actI-orfl and actI-orf2) in the expression cassette was specifically replaced with oxytetracycline ${\beta}-ketoacyl$ synthase otcY-orfl and otcY-orf2). This plasmid-based hybrid PKS cassette generated a novel orange-fluorescent compound structurally different from aloesaponarin II in both S. lividans and S. parvulus. In addition, several additional distinctive blue-fluorescent compounds were detected, when this hybrid PKS cassette was expressed in S. coelicolor B78 (actI-orf2 mutant), implying that the expression of plasmid-based hybrid PKS cassette in Streptomyces species should be an efficient way of generating hybrid type II polyketide compounds.