• Journal of Microbiology and Biotechnology
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• 제19권2호
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• pp.136-139
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• 2009

Avermectin and its analogs are major commercial antiparasitic agents in the fields of animal health, agriculture, and human infections. Previously, comparative transcriptome analysis between the low-producer S. avermitilis ATCC31267 and the high-producer S. avermitilis ATCC31780 using a S. avermitilis whole genome chip revealed that 50 genes were overexpressed at least two-fold higher in S. avermitilis ATCC31780. To verify the biological significance of some of the transcriptomics-guided targets, five putative regulatory genes were individually cloned under the strong-and-constitutive promoter of the Streptomyces expression vector pSE34, followed by the transformation into the low-producer S. avermitilis ATCC31267. Among the putative genes tested, three regulatory genes including SAV213, SAV3818, and SAV4023 exhibited stimulatory effects on avermectin production in S. avermitilis ATCC31267. Moreover, overexpression of SAV3818 also stimulated actinorhodin production in both S. coelicolor M145 and S. lividans TK21, implying that the SAV3818, a putative TetR-family transcriptional regulator, could be a global upregulator acting in antibiotic production in Streptomyces species.

• 한국미생물·생명공학회지
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• 제34권1호
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• pp.15-22
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• 2006

Ochrobactrum anthropi JW-2의 염색체 DNA로부터 paraquat 내성 유전자 pqrA를 포함하는 4,971 bp의 DNA 염기서열을 결정하였다. 염기서열 분석 결과 2개의 불완전한 ORF(orf1, orf5)와 4개의 완전한 ORF(orf2, pqrA, orf3, orf4)가 존재하는 것으로 나타났는데 orf1, pqrA, orf4, orf5는 direct strand에 orf2와 orf3은 reverse complementary strand 존재하였다. Orf1은 개시코돈이 결손된 불완전한 서열로서, response regulator receiver의 ATP binding region과 상동성을 나타내었다. Orf2는 tetR family에 속하는 transcription repressor와 높은 상동성을 나타내었고 H-T-H motif가 존재하는 것으로 나타났다. 따라서 orf2가 pqrA 유전자의 전사조절에 관여하는 repressor로 추정되어 pqrR2로 명명하였다. Orf3은 lysR type의 transcription activator와 높은 상동성을 나타내었고 N-terminal 부위에 H-T-H motif와 C-terminal 부위에 substrate binding domain이 존재하는 것으로 나타났다. 따라서 orf3은 pqrA의 전사조절에 관여하는 transcription activator로 추정되어 pqrR1로 명명하였다. Orf4는 amino acid ABC transporter의 periplasmic amino acid-binding protein과 상동성을 나타내었으며, orf5는 종결 코돈이 없는 불완전한 ORF로서 amino acid ABC transporter의 permease protein과 상동성을 나타내었다. 이와 같은 결과로 미루어 pqrA 유전자 주위에 존재하는 전사조절 유전자들이 paraquat 내성유전자인 pqrA의 발현조절을 통하여 paraquat에 대한 내성획득에 관여하는 것으로 판단되었다.

• Journal of Microbiology and Biotechnology
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• 제20권11호
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• pp.1484-1490
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• 2010

In the Streptomyces hygroscopicus JCM4427 geldanamycin biosynthetic gene cluster, five putative regulatory genes were identified by protein homology searching. Among those genes, gel14, gel17, and gel19 are located downstream of polyketide synthase genes. Gel14 and Gel17 are members of the LAL family of transcriptional regulators, including an ATP/GTP-binding domain at the N-terminus and a DNA-binding helix-turn-helix domain at the C-terminus. Gel19 is a member of the TetR family of transcriptional regulators, which generally act to repress transcription. To verify the biological significance of the putative regulators in geldanamycin production, they were individually characterized by gene disruption, genetic complementation, and transcriptional analyses. All three genes were confirmed as positive regulators of geldanamycin production. Specifically, Gel17 and Gel19 are required for gel14 as well as gelA gene expression.

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.85-91
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• 2001

To construct an efficient Bacillus subtilis expression vector, strong promoters were isolated from the chromosomal DNA libraries of Clostridium acetobutylicum ATCC 4259, Thermoactinomyces sp. E79, and Bacillus thermoglucosidasius KCTC 3400. The $P_{C27}$ promoter cloned from the clostridial chromosmal DNA showed a 5-fold higher promoter strength than the $P_{SP02}$ promoter in the expression of the cat gene, and its sequence was estimated as an upstream region of the predicted hypothetical gene (tet-R family bacterial transcription regulator gene) in C. acetobutylicum. As a promoter element, $P_{C27}$ exhibited putative nucleotide sequences that can bind with bacterial RNAP and the 3'end of the 16S rRNA just upstream of the start codon. In addition, the promoter activity of $P_{C27}$ was distinctively repressed in the presence of glucose. Using $P_{C27}$ as the promoter element, a glucose controllable B. subtilis expression vector was constructed and the lipase gene from Staphylococcus haemolyticus KCTC 8957P was expressed in B. subtilis. When compared with the lipase expression by the T7 promoter induced by IPTG in E. coli, the $P_{C27}$ promoter showed about a 1.5-fold higher expression level in B. subtilis than that without induction.