박테리아의 toxin-antitoxin system과 생명공학기술 응용

김윤지(Yoonji Kim),황지환(Jihwan Hwang) 한국생명과학회 2016 생명과학회지 Vol.26 No.2

Toxin-antitoxin (TA) system은 박테리아와 고세균에서 진화적으로 보존되어 흔히 발견되는 유전적 모듈이다. 기본적으로 이 시스템은 세포 내 toxin과 그들의 억제자로 작용하는 antitoxin으로 구성되어있으며, 현재 총 다섯 가지 유형으로 구분된다. 공통적으로 toxin은 스트레스 조건에서 활성화됨으로써 세포 내 다양한 과정을 억제하는 활성을 가지는데 이는 결과적으로 세포 사멸 혹은 가역적인 생장 저해를 일으킨다. Toxin의 이러한 효과들은 유전자 발현의 조절, 성장 조절, programmed cell arrest, programmed cell death, persister cell의 형성, 박테리오파지 방어기작, 가동성 유전인자의 안정화, 플라스미드 유지 기작 등 다양한 생리학적 역할을 나타낸다. 그러므로 TA system은 일반적인 스트레스 반응모듈로서 여겨진다. 하지만 이를 역이용한다면 TA system으로부터 toxin을 활성화 시키는 인자를 개발하여 새로운 항균 물질로 이용할 수 있다. 그뿐만 아니라 TA system은 toxin의 세포 사멸효과를 이용하여 원하는 타겟 유전자가 존재하는 세포만 선택적으로 살아남도록 하는 효율적인 클로닝 전략에 이용될 수 있다. 또한, toxin의 서열 특이적 리보핵산 가수분해효소 활성을 이용하여 타겟 단백질 이외의 단백질 합성을 막아 효과적인 단일 단백질 대량 생산을 위해서도 이용할 수 있다. 더 나아가 일부 TA system의 toxin은 진핵 세포에서도 세포 독성을 나타내기 때문에 암세포, 바이러스 감염 세포에서 toxin의 발현을 유도하여 세포 사멸을 일으킴으로써 인간의 질병 치료로 이어질 수 있다. Toxin-antitoxin (TA) systems are ubiquitous genetic modules that are evolutionally conserved in bacteria and archaea. TA systems composed of an intracellular toxin and its antidote (antitoxin) are currently classified into five types. Commonly, activation of toxins under stress conditions inhibits diverse cellular processes and consequently induces cell death or reversible growth inhibition. These effects of toxins play various physiological roles in such as regulation of gene expression, growth control (stress response), programmed cell arrest, persister cells, programmed cell death, phage protection, stabilization of mobile genetic elements or postsegregational killing of plasmid-free cells. Accordingly, bacterial TA systems are commonly considered as stress-responsive genetic modules. However, molecule screening for activation of toxin in TA system is available as development of antimicrobial agents. In addition, cytotoxic effect induced by toxin is used as effective cloning method with antitoxic effect of antitoxin; consequently cells containing cloning vector inserted a target gene can survive and false-positive transformants are removed. Also, TA system is applicable to efficient single protein production in biotechnology industry because toxins that are site-specific ribonuclease inhibit protein synthesis except for target protein. Furthermore, some TA systems that induce apoptosis in eukaryotic cells such as cancer cells or virus-infected cells would have a wide range of applications in eukaryotes, and it will lead to new ways of treating human disease. In this review, we summarize the current knowledge on bacterial TA systems and their applications.

Improved Purification Process for Cholera Toxin and its Application to the Quantification of Residual Toxin in Cholera Vaccines

( Hyun Jang ),( Hyo Seung Kim ),( Jeong Ah Kim ),( Jin Ho Seo ),( Rodney Carbis ) 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.1

A simplified method for the purification of cholera toxin was developed. The 569B strain of Vibrio cholerae, a recognized hyper-producer of cholera toxin, was propagated in a bioreactor under conditions that promote the production of the toxin. The toxin was separated from the bacterial cells using 0.2-μm crossflow microfiltration, the clarified toxin was passed through the membrane into the permeate, and the bacterial cells were retained in the retentate. The 0.2-μm permeate was then concentrated 3-fold and diafiltered against 10 mM phosphate buffer; pH7.6, using 30-kDa crossflow ultrafiltration. The concentrated toxin was loaded onto a cation exchange column, the toxin was bound to the column, and most of the impurities were passed unimpeded through the column. The toxin was eluted with a salt gradient of phosphate buffer, pH7.0, containing 1.0M NaCl. The peak containing the toxin was assayed for cholera toxin and protein and the purity was determined to be 92%. The toxin peak had a low endotoxin level of 3.1 EU/μg of toxin. The purified toxin was used to prepare antiserum against whole toxin, which was used in a GM1 ganglioside-binding ELISA to determine residual levels of toxin in an oral inactivated whole-cell cholera vaccine. The GM1 ganglioside-binding ELISA was shown to be very sensitive and capable of detecting as little as 1 ng/ml of cholera toxin.

Clinical and Microbiologic Characteristics of Clostridium difficile Infection Caused by Binary Toxin Producing Strain in Korea

김지은,서미란,강정옥,최태열,배현주 대한감염학회 2013 Infection and Chemotherapy Vol.45 No.2

Background: Binary toxin-producing Clostridium difficile infections (CDI) are known to be more severe and to cause higher case fatality rates than those by binary toxin-negative isolates. There has been few data of binary toxin-producing CDI in Korea. Objective of the study is to characterize clinical and microbiological trait of CDI cause by binary-toxin producing isolates in Korea. Materials and Methods: From September 2008 through January 2010, clinical characteristics, medication history and treatment outcome of all the CDI patients were collected prospectively. Toxin characterization, PCR ribotyping and antibiotic susceptibility were performed with the stool isolates of C. difficile . Results: During the period, CDI caused by 11binary toxin-producing isolates and 105 toxin A & toxin B-positive binary toxin-negative isolates were identified. Comparing the disease severity and clinical findings between two groups, leukocytosis and mucoid stool were more frequently observed in patients with binary toxin-positive isolates (OR: 5.2, 95% CI: 1.1 to 25.4, P = 0.043; OR: 7.6, 95% CI: 1.6 to 35.6, P = 0.010, respectively), but clinical outcome of 2 groups did not show any difference. For the risk factors for acquisition of binary toxin-positive isolates, previous use of glycopeptides was the significant risk factor (OR: 6.2, 95% CI: 1.4 to 28.6, P = 0.019), but use of probiotics worked as an inhibitory factor (OR: 0.1, 95% CI: 0.0 to 0.8; P = 0.026). PCR ribotypes of binary toxinproducing C. difficile showed variable patterns: ribotype 130, 4 isolates; 027, 3 isolates; 267 and 122, 1 each isolate and unidentified C1, 2 isolates. All 11 binary toxin-positive isolates were highly susceptible to clindamycin, moxifloxacin, metronidazole, vancomycin and piperacillin-tazobactam, however, 1 of 11 of the isolates was resistant to rifaximin. Conclusions: Binary toxin-producing C. difficile infection was not common in Korea and those isolates showed diverse PCR ribotypes with high susceptibility to antimicrobial agents. Glycopeptide use was a risk factor for CDI by those isolates.

Fusarium 균주의 배양 조건 및 생리적 조건에 따른 T-2 toxin의 생성 조건

홍성희,양규환 한국미생물학회 2000 미생물학회지 Vol.36 No.2

불와전 균류인 Fusarium s^g pp.를 이용하여 여러 가지 배양조건과 생리적 영향에 따른 균주의 성장 및 T-2 toxin의 생성에 관하여 고찰하였다. T-2 toxin 의 검출방법은 thin layer chromatography (TCL) 법과 미생물학적 검출방법을 사용하였다. 고체 배지의 경우 횐옥수수 가루(Quaker사 제품)베지에서 다른 곡물보다 많은 양의 T-2 toxin이 생성되었으며,비교적 깨끗한 T-2 toxin이 정제되었다. 이 경우 배지 100g당 약 700 mg의 T-2 toxin이 생성되었으며, 그중 약 30%정도가 깨끗한 결정으로 정제되었다. 고온(20-$25^{\circ}C$)에서는 생장은 많았으나, T-2 toxin의 생성은 적었으며, 저온(10-$15^{\circ}C$)에서는 비교적 생장이 적었지만, T-2 toxin의 생성이 많았고, 젖당, 글리세롤, 솔비톨의 경우는 적었다. 유일 탄소원으로 구연산과 초산은 이용하지 못하였으며, 녹발의 경우 생장은 많았으나 T-2 toxin의 생성양은 적었다. 질소원의 경우 $NaNO_2$를 제외하고는 $(NH_4)_2NO_4$, $NH_4Cl_3$, $NH_4NO_3$, $KNO_3$ 를 거의 동일하게 이용하였다. 초기 pH값에 생성과 균주의 성장은 pH4.0-5.0일 경우 최적을 나타냈으며 ph6.0이상에서는 성장도 저하되고, T-2 toxin생성도 적었다. 회전속도에 따른 T-2 toxin 생성과 균주의 성장을 보면 회전속도가 속돠 증가함에 따라 균주의 생장과 T-2 toxin 생성량이 모두 증가하였다. $15^{\circ}C$에서 7일간 배양 후, $25^{\circ}C$로 옮겨 7일간 배양하여, toxin의 생성을 보면, $15^{\circ}C$에 7일간 배양했을 때보다 T-2 toxin양이 적었다. 이는 생성되었던 T-2 toxin이 분해되었음을 보여주는 것이다. 이상의 결과를 볼 때 T-2 toxin 대사 경로는 온도에 의한 효소 억제 또는 효소 유지 시스템에 의해 조절되는 것이라고 생각할 수 있다. The cultural and physiological conditions for the T-2 toxin [4,15-diacetoxy-8-(3-mety1butyloxy)-12,13- epoxy-trichothec-9-en-3-01, $C_{24}H_{30}O_9$] production by Fusarium spp. were studied. Thin layer chromatography (TLC) assay and the microbiological assay uslng Rhodotomla rubra were used to quantitate tbe T- 2 toxin. Among the four strains of Fusarium spp., F tn'cinctum NRRL 3299 was best for T-2 toxin production. In solid culture, white com grit medium was best for T-2 toxm production. Temperature played a critical role in the production of T-2 toxin. T-2 toxin production was favored by long duration of low-temperature incubation. The growth and toxin production were relatively high on galactose, fructose, glucose, and sucrose media, when each was used as a sole carbon source, and relatively low on sorbitol, glycerol, and lactose media. For nitrogen sources, $NH_4^(+) and NO_3^{-}were used well as a sole nitrogen source, but $NO_2^-$ was not used. Initial pH and speed of shaker also affected the production of T-2 toxin. From temperature shifting experiment, it is clear that T-2 toxin metabolic pathway is regulated by temperature-dependent enzyme depression or enzyme induction system.

Molecular Cloning of Two cDNAs Encoding an Insecticidal Toxin from the Spider, Araneus ventricosus, and Construction of a Recombinant Baculovirus Expressing a Spider Toxin

Chung, Eun-Hwa,Lee, Kwang-Sik,Han, Ji-Hee,Je, Yeon-Ho,Chang, Jin-Hee,Roh, Jong-Yul Korean Society of Sericultural Science 2002 International Journal of Industrial Entomology Vol.4 No.1

We have cloned cDNAs encoding toxin from the spider, Araneus ventricosus, and constructed a recombinant baculovirus expressing the insecticidal toxin. The cDNAs encoding toxin were cloned from the cDNA library of A. ventricosus. Sequence analysis of the cDNAs encoding the toxin of A. ventricosus revealed that the 240 bp cDNA for AvTox-1 and 192 bp cDNA for AvTox-2 have an open reading frame of 80 and 64 amino acid residues, respectively. The deduced protein sequence of the toxin genes of AvTox-1 and AvTox-2 was aligned to that of the snack Anemonia sulcata and scorpion Centruroides limpidus limpidus, respectively. Northern blot analysis indicated that AvTox-2 toxin gene showed a fat body-spe-cific expression pattern at the transcriptional level. Furthermore, we have explored the possibility of improving baculovirus by incorporating the A. vontricosus toxin gene into Bombyx mori nuclear polyhedrosis virus genome under the control of polyhedrin promoter, The AvTox-2 toxin gene was expressed as approximately 5.8 kDa band in the recombinant baculovirus-injected silkworm larvae. Bioassays with the recombinant virus expressing AvTox-2 on 5th instar silkworm larvae demonstrated a decrease in the time to kill $(LT_{50} days)$ compared to wild-type BmNPV-Kl $(LT_{50} 6.72 days)$ in the injection of 10 viruses. These results indicate that A. ventricosus toxin is a novel member of the spider toxin family, suggesting that the toxin gene can be used in recombinant baculoviruses to reduce insect feeding damage and increase the speed of insect kill.

Cell Growth Inhibition and Induction of Apoptosis by Snake Venom Toxin in Ovarian Cancer Cell via Inactivation of Nuclear Factor κB and Signal Transducer and Activator of Transcription 3

Ju Kyoung Song,Jin Tae Hong,Mi Ran Jo,Mi Hee Park,Ho Sueb Song,Byeong Jun An,Min Jong Song,Sang Bae Han 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.5

Snake venom toxin from Vipera lebetina turanica induces apoptosis in many cancer cell lines, but there is no study about the apoptotic effect of snake venom toxin on human ovarian cancer cells. In this study, we investigated the apoptotic effect of snake venom toxin in human ovarian cancer PA-1 and SK-OV3 cells. Snake venom toxin dose dependently (0~10 μg/mL) inhibited ovarian cancer cell growth with IC50 values 4.5 μg/mL in PA-1 cells, and 6.5 μg/mL in SKOV3 cells. Our results also showed that apoptotic cell death increased by snake venom toxin in a dose dependent manner (0~10 μg/mL). Consistent with increased cell death, snake venom toxin increased the expression of pro-apoptotic protein Bax and caspase-3, but down-regulated anti-apoptotic protein Bcl-2. Untreated ovarian cancer cells showed a high DNA binding activity of nuclear factor B (NF-κB), but it was inhibited by snake venom toxin accompanied by inhibition of p50 and p65 translocation into the nucleus as well as phosphorylation of inhibitory κB. Snake venom toxin also inhibited DNA binding activity of the signal transducer and activator of transcription 3 (STAT3). Moreover, the combination treatment of NF-κB (salicylic acid, 1 or 5 μM) and STAT3 (stattic, 1 μM) with snake venom toxin (1 μg/mL) further enhanced cell growth inhibitory effects of snake venom toxin. These results showed that snake venom toxin from Vipera lebetina turanica caused apoptotic cell death of ovarian cancer cells through the inhibition of NF-κB and STAT3 signal, and suggested that snake venom toxin may be applicable as an anticancer agent for ovarian cancer.

Clostridium difficile Toxin A Induces Reactive Oxygen Species Production and p38 MAPK Activation to Exert Cellular Toxicity in Neuronal Cells

( Peng Zhang ),( Ji Hong ),( I Na Yoon ),( Jin Ku Kang ),( Jae Sam Hwang ),( Ho Kim ) 한국미생물생명공학회(구 한국산업미생물학회) 2017 Journal of microbiology and biotechnology Vol.27 No.6

Clostridium difficile releases two exotoxins, toxin A and toxin B, which disrupt the epithelial cell barrier in the gut to increase mucosal permeability and trigger inflammation with severe diarrhea. Many studies have suggested that enteric nerves are also directly involved in the progression of this toxin-mediated inflammation and diarrhea. C. difficile toxin A is known to enhance neurotransmitter secretion, increase gut motility, and suppress sympathetic neurotransmission in the guinea pig colitis model. Although previous studies have examined the pathophysiological role of enteric nerves in gut inflammation, the direct effect of toxins on neuronal cells and the molecular mechanisms underlying toxin-induced neuronal stress remained to be unveiled. Here, we examined the toxicity of C. difficile toxin A against neuronal cells (SH-SY5Y). We found that toxin A treatment time- and dose-dependently decreased cell viability and triggered apoptosis accompanied by caspase-3 activation in this cell line. These effects were found to depend on the up-regulation of reactive oxygen species (ROS) and the subsequent activation of p38 MAPK and induction of p21^Cip1/Waf1. Moreover, the N-acetyl-Lcysteine (NAC)-induced down-regulation of ROS could recover the viability loss and apoptosis of toxin A-treated neuronal cells. These results collectively suggest that C. difficile toxin A is toxic for neuronal cells, and that this is associated with rapid ROS generation and subsequent p38 MAPK activation and p21^Cip1/Waf1 up-regulation. Moreover, our data suggest that NAC could inhibit the toxicity of C. difficile toxin A toward enteric neurons.

장내세균에 의한 Trichothecene Mycotoxins의 대사 : (I) T-2 toxin의 대사

이웅수 忠州大學校 2008 한국교통대학교 논문집 Vol.43 No.-

Trichothecene mycotoxins are a chemically related group of toxic fungal metabolites produced by a number of species of the fungi such as Fusarium, Cephalosporium, Trichothecium, Myrothecium, Stachybotrys and Trichoderma, and are responsible for mycotoxicoses as causative agents in a wide variety of animal and human health problems. Especially, T-2 toxin is a secondary metabolite produced by Fusarium spp. such as F. tricinctum, F. poae and F. sporotrichioides etc., and is often found in agricultural products and feeds including cereals, and is a potent cytotoxic and immunodepressive trichothecene mycotoxin, and causative agent of moldy corn toxicosis and alimentary toxic aleukia(ATA), and induces acute toxicity such as leukocytosis, hemorrhage and dermal edema, followed by death in animals. In order to elucidate the possible metabolism of T-2 toxin by rat and human intestinal bacteria, this research was carried out. T-2 toxin transformed into HT-2 toxin and unknown metabolite by cultured intestinal bacteria in the anaerobic condition. The amount of HT-2 toxin was decreased, but unknown metabolite was increased by subsequent incubation. This metabolite was elucidated to deepoxy HT-2 toxin by NMR and mass spectra data. It was suggested that T-2 toxin was deepoxidized after deacetylation to HT-2 toxin by the intestinal bacteria. This deepoxy HT-2 toxin was transformed into HT-2 toxin and 15-deacetyl-deepoxy HT-2 toxin by liver microsome of PCB-treated rat in the presence of NADPH and oxygen. These results suggest that the epoxide group of trichothecene mycotoxins is reduced by intestinal bacteria and re-oxidized by hepatic microsomal enzyme of rat.

Use of Clostridium septicum Alpha Toxins for Isolation of VariousGlycosylphosphatidylinositol-Deficient Cells

신동준,최현일,홍영진 한국미생물학회 2005 The journal of microbiology Vol.43 No.3

In eukaryotic cells, various proteins are anchored to the plasma membrane through glycosylphosphatidylinositol (GPI). To study the biosynthetic pathways and modifications of GPI, various mutant cells have been isolated from the cells of Chinese hamster ovaries (CHO) supplemented with several exogenous genes involved in GPI biosynthesis using aerolysin, a toxin secreted from gram-negative bacterium Aeromonas hydrophila. Alpha toxin from Gram-positive bacterium Clostridium septicum is homologous to large lobes (LL) of aerolysin, binds GPI-anchored proteins and possesses a cell-destroyingmechanism similar to aerolysin. Here, to determine whether alpha toxins can be used as an isolation tool of GPI-mutants, like aerolysin, CHO cells stably transfected with several exogenous genes involved in GPI biosynthesis were chemically mutagenized and cultured in a medium containing alpha toxins. We isolated six mutants highly resistant to alpha toxins and deficient in GPI biosynthesis. By genetic complementation, we determined that one mutant cell was defective of the second subunit of dolichol phosphate mannose synthase (DPM2) and other five cells were of a putative catalytic subunit of inositol acyltransferase (PIG-W). Therefore, C. septicum alpha toxins are a useful screening probe for the isolation of various GPI-mutant cells. In eukaryotic cells, various proteins are anchored to the plasma membrane through glycosylphosphatidylinositol (GPI). To study the biosynthetic pathways and modifications of GPI, various mutant cells have been isolated from the cells of Chinese hamster ovaries (CHO) supplemented with several exogenous genes involved in GPI biosynthesis using aerolysin, a toxin secreted from gram-negative bacterium Aeromonas hydrophila. Alpha toxin from Gram-positive bacterium Clostridium septicum is homologous to large lobes (LL) of aerolysin, binds GPI-anchored proteins and possesses a cell-destroyingmechanism similar to aerolysin. Here, to determine whether alpha toxins can be used as an isolation tool of GPI-mutants, like aerolysin, CHO cells stably transfected with several exogenous genes involved in GPI biosynthesis were chemically mutagenized and cultured in a medium containing alpha toxins. We isolated six mutants highly resistant to alpha toxins and deficient in GPI biosynthesis. By genetic complementation, we determined that one mutant cell was defective of the second subunit of dolichol phosphate mannose synthase (DPM2) and other five cells were of a putative catalytic subunit of inositol acyltransferase (PIG-W). Therefore, C. septicum alpha toxins are a useful screening probe for the isolation of various GPI-mutant cells.

Studies for Reestabilishment of Approval Toxin Amount in Paralytic Shellfish Poison-Infested Shellfish 5. Comparison of Toxicity and Toxin Composition of Paralytic Shellfish Poison between Blue mussel, Mytilus edulis and Oyster, Crassostrea gigas

Shin, Il-Shik,Kim, Young-Man The Korean Society of Food Hygiene and Safety 2000 한국식품위생안전성학회지 Vol.15 No.4

1976년과 1997년 남해안의 거제도 외포리에서 채취한 진주담치와 굴의 독력 덴 독소성분을 비교 조사하였다. 독성은 진주담치가 굴에 비하여 약 10배 정도 높았으며(1996년, 진주담치, 8,670 $\mu\textrm{g}$, 굴 860$\mu\textrm{g}$; 1997년, 진주담치 5,657 $\mu\textrm{g}$, 굴 531$\mu\textrm{g}$/100g), 독화기간도 진주담치가 굴에 비하여 길었다. 두 종류의 시료 모두 독소 주성분은 Cl 및 C2 (20~65%)와 gonyautoxin 1, 2, 3, 4 (38~78%)이었다. 그리고 독화초기에는 11$\beta$-epimer toxin(C2, GTX4)의 비율이 25~56mo1e%(1996년)와 25~80mo1e% (1997년)로 11$\alpha$-epimer toxin(Cl, GTX2)의 비율도다 높았다. 그러나 독화기간이 지남에 따라 11$\alpha$-epimer toxin의 비율이 41~57mo1e%(1996년)와 25~56mo1e%(1997년)로 11$\beta$-epimer toxin의 비율보다 높게 나타났다. 이와 같은 독소성분 조성의 변화는 패류내에서 독소가 대사되기 때문인 것으로 추측된다. The toxicity and toxin composition between blue mussel, Mytilus edulis and oyster, Crassostrea gigas collected at Woepori in Ko je island in South Coast of Korea in 1996 and 1997 were compared. The highest toxicity score was about 10 times higher in blue mussel than oyster (blue mussel, 8,670 $\mu\textrm{g}$; oyster, 860$\mu\textrm{g}$ in 1996, blue mussel, 5,657 $\mu\textrm{g}$/100g in 1997). The blue mussel also retained its toxicity for slightly longer period than oyster. In the both shellfish, PSP was composed almost exclusively of C toxicity (Cl and C2, 20~65%) and gonyautoxins (GTXl, 2, 3, and 4, 38~78%). In the early period of toxin accumulation, the ratio of 11$\beta$-epimer toxins (C2, GTX4) whose amount was 25~56 mole% (5th March to 12th April in 1996) and 25~80 mole% (18th March to 7th April in 1997), were higher than that of 11-epimer toxins (Cl, GTX2) whose amount was 41~57 mol%(27th May to 3rd June in 1996) and 25~56 mole% (29th April to 12th May in 1997), became higher than that of 11-epimer toxins. The toxin compositions in the both samples changed on a daily basis, presumably owing to metabolism of the toxin in the bivalves.