• BMB Reports
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• 제49권3호
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• pp.135-136
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• 2016

Small interfering RNAs (siRNAs) have been developed to intentionally repress a specific gene expression by directing RNA-induced silencing complex (RISC), mimicking the endogenous gene silencer, microRNAs (miRNAs). Although siRNA is designed to be perfectly complementary to an intended target mRNA, it also suppresses hundreds of off-targets by the way that miRNAs recognize targets. Until now, there is no efficient way to avoid such off-target repression, although the mode of miRNA-like interaction has been proposed. Rationally based on the model called "transitional nucleation" which pre-requires base-pairs from position 2 to the pivot (position 6) with targets, we developed a simple chemical modification which completely eliminates miRNA-like off-target repression (0%), achieved by substituting a nucleotide in pivot with abasic spacers (dSpacer or C3 spacer), which potentially destabilize the transitional nucleation. Furthermore, by alleviating steric hindrance in the complex with Argonaute (Ago), abasic pivot substitution also preserves near-perfect on-target activity (∼80-100%). Abasic pivot substitution offers a general means of harnessing target specificity of siRNAs to experimental and clinical applications where misleading and deleterious phenotypes from off-target repression must be considered.

• Journal of Microbiology and Biotechnology
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• 제8권1호
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• pp.21-27
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• 1998

The xylA gene of Bacillus stearothermophilus encoding the major ${\beta}$-xylosidase was previously cloned and sequenced. In the present study we examined the regulation of the cloned xylA gene expression in Bauillus subtilis MW15 carrying the xylA::aprA fusion plasmids. The induction of the fused xylA gene expression remained uninfluenced by any of the carbon sources tested but the gene expression was repressed about 2-3 fold in the presence of glucose. Two CRE-like sequences (CRE-1: nucleotides ＋ 124 to ＋136 and CRE-2: ＋247 to ＋259) were recognized within the reading frame region of the xylA gene. The deletion experiments showed that the CRE-2 sequence had a role in catabolite repression (CR) as a true CRE of the xylA gene, but the CRE-1 had no effect on CR of the xylA gene expression. Surprisingly, the deletion of the CRE- 1 sequence reduced about 2~3 fold of the expression of the xylA fused gene. The repression ratios of the xylA gene expression were estimated to be about 0.4 from the assay of subtilisin activity, and about 0.3 at the level of transcription by determining the amounts of xylA transcripts in B. subtilis. While, the level of CR of the xylA gene was assessed to be about l0-fold in previous work when the relative amounts of the xylA transcripts were measured in B. stearothermophilus.

• 자연과학논문집
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• 제18권1호
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• pp.29-38
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• 2007

호 알칼리성이며 고온성인 Bacillus cereus TA-11이 세포내로 생성하는 invertase의 생합성 조절 양상을 조사하였다. Bacillus cereus TA-11의 세포내 invertase는 10 mM sucrose의 180분 처리와 25 mM raffinose의 90분 처리에서 각각 효율적으로 유도되었다. 또한 glucose는 sucrose에 의한 invertase의 유도를 억제하였고 cAMP첨가는 catabolite repression을 감소시키지 못하였다.

• 한국발생생물학회지:발생과생식
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• 제27권1호
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• pp.39-46
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• 2023

Pumilio (Pum) is an RNA-binding protein and translational repressor important to diverse biological processes. In the Drosophila ovary, Pum is expressed in female germline stem cells (GSCs), wherein it acts as an intrinsic stem cell maintenance factor via repressing target mRNAs that are as yet mostly unknown. Pum recognizes the Pum binding sequence (PBS) in the mRNA 3'UTR through its C-terminus Puf domain. Translational repression is mediated through its N-terminal domain, but the molecular mechanism remains largely unknown. We previously showed that Bag-of-marbles, a critical differentiation-promoting factor of female GSCs, physically interacts with the N-terminus of Pum. We further showed that this interaction is critical to Bam inhibition of Pum repressive action in cultured cells, but the physiological relevance was not addressed. Here we design an in vivo GFP translational reporter bearing the PBS in its 3'UTR and show that GFP expression is reduced in cells wherein Pum is known to be active. Furthermore, we demonstrate in pum mutant ovary that this GFP repression requires Pum, and also that the sensor faithfully monitors Pum activity. Finally, we show that forced expression of Bam inhibits Pum-mediated repression, validating that Bam inhibits Pum activity in vivo.

• Journal of Microbiology and Biotechnology
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• 제11권1호
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• pp.131-137
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• 2001

Previous work has identified that only the catabolite responsive element A (creA; previously called cre-2) out of two potential cre sequences (cre-1: nucleotide +160 to +173 and cre-2: +173 to +186), recognized within the coding region of the xylanaseA gene (xynA) of Bacillus stearothermophilus No.236, was actually, was actually involved in the carbon catabolite repression(CCR) of xynA expression in B. subtilis. However, the level of CCR of xynA expression in the original B.stearothermophilus No.236 strain (70-fold repression). Therefore, to search for an additional cre element in the promoter region, the upstream region of the xynA gene was subcloned by chromosome walking, and as a result, another potential cre element (nucleotide -124∼-137; designated creB) was recognized in this region. The cre-like sequence revealed a high homology to the cre consensus sequence. The xylanase activity of B. subtilis MW15 bearing pWPBR14 (containing creA and creB) cultured in a medium containing xylose as the sole carbon source was about 7.7 times higher than that observed for the same culture containing glucose. B. subtilis MW15 bearing pWPBR23 (containing only creA) produced an activity about 2.4 times higher. This pattern of CCR was confirmed using derivatives of xynA::aprA fusion plasmids. Furthermore, a measurement of the amounts of the xynA transcript showed a similar pattern as that for the production of xylanase. In addition, the synthesis of xylanase in B. subtilis QB7115 [a catabolite control protein A (ccpA) mutant strain] carrying pWPBR14 was almost completely relieved from glucose repression. Together, these results lead to a conclusion that the CCR of the expression of the xynA gene is mediated by CcpA binding at creA and creB sites in B. subtilis.

• 한국균학회지
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• 제13권4호
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• pp.235-241
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• 1985

본 연구는, catabolic repression시킨 효모세포를 완전배지와 최소배지에서 derepression시켜, 배양시기 및 인산 첨가농도(free, limited, sufficient)에 따른 5종의 다당류 합성변화를 조사하였다. 그리고 다당류 합성과 무기폴리인산 축적량 및 인지질 합성 사이의 상관지수를 구하여 합성시 관련되는 유의한 정도를 검정하였다. 그 결과, 최소배지에서 catabolic derepression시킨 효모세포가, 완전배지에서 derepression시킨 세포에 비하여, glycogen의 합성이 발리 그리고 많이 일어났고, acid soluble glycogen type이 주된 함량을 나타내었으며, alkali soluble glycogen은 당이 많이 소모된 24시간 배양 후에 소량 나타났다. 무기인산 첨가정도에 따라 total glycogen합성이 일정한 비율로 빨리 그리고 높게 일어났다. Glucan의 합성에는 ALPase 중 ALPase "C"가 관련할 것으로 추정되었다. Mannan은 ezponential phase초기와 정체기때, acid soluble 분획은 정체기때 최대함량을 나타내었다. Mannan 합성과 poly-P "C"축적량 사이의 상관지수는 0.866, mannan합성과 인지질 사이의 상관지수는 0.726으로 나타나 매우 유의하였다.

• KSBB Journal
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• 제9권3호
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• pp.339-345
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• 1994

포도당 억제현상은 유전자 조작 및 induder에 의해 감소될 수 있다. UA8G와 GALl TATA box 사 이에서의 유전자 삭제는 포도당 억제현상을 줄이고 갈락토스가 존재하지 않는 조건에서 지속적인 유전자 발현을 도모했다. 상대적 inducer의 양(갈락토스/포 도당 농도의 비)은 유전자 발현 및 포도당 억제현상 에 영향을 주었다. 포도당 억제현상은 상대적 inducer의 양이 증가함에 따라 2-5배 정도 감소하였다. 또한 유전자 발현은 플라즈미드의 수에 좌우된다. 배지에 갈락토스만 았을 경우 유전자 발현은 플라즈 마드의 수가 증가함에 따라 증가하였다. 반면에 배지에 포도당과 갈락토스가 함께 있는 경우 (2% G Glu+2% Gal), 플라즈미드의 수는 유전자 발현에 별다른 영향을 주지 못했다. 그러나 높은 상대적 m­d ducer 양이 배지에 있는 경우 (0.4% Glu+0.8% Gal), 플라즈미드의 수가 증가함에 따라 유전자 발 현이 증가하였다. 즉, 포도당 억제현상을 줄임으로써 유전자 발현효율을 높이고자 할 때 갈락토스의 농도 를 증가시키는 경우보다는 포도당의 농도를 낮춤으 로써 상대적 inducer의 양음 높여 유전자 발현을 유 도하는 방법이 보다 효율적인 것으로 나타났다.

• BMB Reports
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• 제28권4호
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• pp.342-347
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• 1995

The induction of glucoamylase biosynthesis from the yeast Candida tsukubaensis by different carbon sources was investigated by using either an enzyme activity assay or immunoblot analysis. The induction by C. tsukubaensis appears to be independent of the carbon sources, although the level of enzyme activity was lower in slowly utilizable carbon sources such as galactose. This glucoamylase is a constitutive enzyme and its biosynthesis is resistant to carbon catabolite repression. Glucose was more effective for the enzyme induction than starch, maltose or glycerol. In addition, this enzyme is regulated by both induction and repression.

• 한국식품영양학회지
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• 제15권2호
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• pp.126-130
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• 2002

고온성이며 호알칼리성인 Bacillus sp. TA-11이 생성하는 Invertase의 생합성 조절 기작을 규명하고자 먼저 이들의 유도와 억제에 관하여 검토하였다. Invertase는 10mM sucrose을 함유한 생합성 조절배지에서 3시간에 효율적으로 유도되었고 glucose는 sucrose에 의한 invertase 유도를 inducer exclusion 방식으로 억제시켰다. CAMP의 첨가로 glucose에 의한 catabolic repression이 다소 줄어들었다.

• Asian-Australasian Journal of Animal Sciences
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• 제21권1호
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• pp.144-154
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• 2008

The rumen microbial ecosystem produces methane as a result of anaerobic fermentation. Methanogenesis in the rumen is thought to represent a 2-12% loss of energy intake and is estimated to be about 15% of total atmospheric methane emissions. While methanogenesis in the rumen is conducted by methanogens, PCR-based techniques have recently detected many uncultured methanogens which have a broader phylogenetic range than cultured strains isolated from the rumen. Strategies for reduction of methane emissions from the rumen have been proposed. These include 1) control of components in feed, 2) application of feed additives and 3) biological control of rumen fermentation. In any case, although it could be possible that repression of hydrogen-producing reactions leads to abatement of methane production, repression of hydrogen-producing reactions means repression of the activity of rumen fermentation and leads to restrained digestibility of carbohydrates and suppression of microbial growth. Thus, in order to reduce the flow of hydrogen into methane production, hydrogen should be diverted into propionate production via lactate or fumarate.