• 한국미생물·생명공학회지
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• 제34권3호
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• pp.278-287
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• 2006

토양으로부터 분리한 P. polymyxa 균주가 생산하는 CFTase의 각 repeat region의 결손 변이체를 제작하였으며 그에 따른 야생형 효소와 변이 효소의 활성변화 및 효소특성을 비교 검토하였다. 야생형 CFTase를 CFT148로, N-말단의 R1과 R3를 제거한 결손변이체 CFTase를 CFT108로, C-말단의 R4를 제거한 결손변이체는 CFT130, 모든 R 영역을 제거한 것은 CFT88로 명명하였다. 각각 정제된 재조합 단백질은 148 kDa, 108 kDa, 130 kDa, 그리고 88 kDa의 크기를 나타내었다. Inulin을 기질로 각 재조합 단백질의 활성을 검토한 결과 CFT108은 CF생성, CF분해 반응을 모두 가지고 있었으며 CFT130, CFT88의 경우에는 CF생성 활성을 나타내지 않았으며 endo-inulinae와 동일한 inulin 분해활성을 나타내었다. 따라서 N-말단의 repeat region인 R1과, R3의 역할은 균체 외로의 분비를 담당하며 C-말단의 R4영역은 CFTase의 중요 활성인 cyclization반응을 담당하고 있는 것으로 확인되었다. Repeat region의 모두 제거한 결손 변이체는 기질 inulin을 F2-F4 사이의 중합도를 가진fructooligosaccharide를 생산하는 endo-inulinase의 활성을 가지고 있었다. CFTase는 다기능 효소로 여러 domain으로 구성되어 있으며 각 domain의 결손에도 단백질의 활성을 유지하였으며, 특히 결손 변이체 CFT108은 고효율의 CF 생산이 가능하여 산업적으로 유용하게 사용될 수 있는 효소이다.

• Journal of Microbiology
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• 제37권4호
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• pp.256-262
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• 1999

Latent membrane protein 1 (LMP1) of the Epstein-Barr virus (EBV) is an integral membrane protein with six transmembrane domains, which is essential for EBV-induced B cell transformation. LMP1 functions as a constitutively active tumor necrosis factor receptor (TNFR) like membrane receptor, whose signaling requires recruitment of TNFR-associated factors (TRAFs) and leads to NF-${\kappa}B$ activation. NF-${\kappa}B$ activation by LMP1 is critical for B cell transformation and has been linked to many phenotypic changes associated with EBV-induced B cell transformation. Deletion analysis has identified two NF-${\kappa}B$ activation regions in the carboxy terminal cytoplasmic domains of LMP1, termed CTAR1 (residues 194-232) and CTAR2 (351-386). The membrane proximal C-terminal domain was precisely mapped to a PXQXT motif (residues 204-208) involved in TRAF binding as well as NF-${\kappa}B$ activation. In this study, we dissected the CTAR2 region, which is the major NF-${\kappa}B$ signaling effector of LMP1, to determine a minimal functional sequence. A series of LMP1 mutant constructs systematically deleted for the CTAR2 region were prepared, and NF-${\kappa}B$ activation activity of these mutants were assessed by transiently expressing them in 293 cells and Jurkat T cells. The NF-${\kappa}B$ activation domain of CTAR2 appears to reside in a stretch of 6 amino acids (residues 379-384) at the end of the carboxy terminus.

• 생명과학회지
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• 제32권3호
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• pp.241-248
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• 2022

NF-κB는 염증과 선천성 면역에 중요한 전사인자이며 anti-apoptotic gene을 유도하여 세포의 생존과 발암에도 깊이 연관되어 있으며 많은 신호전달분자 및 신호전달회로와 연결되어있다. 한편, Hsp90는 NF-κB의 활성을 조절한다는 보고가 이루어졌으나 그 구체적인 기전은 알려져 있지 않다. 본 연구에서는 IKK compelx를 구성하는 인자들의 발현 plasmid를 이용하여 NF-κB의 활성조절에서 Hsp90와 IKKγ의 연관성 및 역할을 연구하였다. 그 결과 Hsp90는 IκBα의 인산화와 분해를 촉진하여 NF-κB를 활성화시켰고, NIK과 LPS에 의한 NF-κB의 활성화는 Hsp90에 의해 더욱 활성이 증가하였다. IKKγ는 Hsp90에 의해 증가된 IκBα의 인산화와 분해를 더욱 촉진함으로써 Hsp90의 NF-κB 활성화 작용을 상승시켰다. 이러한 Hsp90와 IKKγ에 의한 NF-κB의 활성화 현상은 항상 활성화 된 상태를 유지하는 IKKβ-EE mutant를 이용한 검토에서도 입증되었다. 또한 IKKγ의 deletion mutant를 이용한 검토에서 IKKγ의 N-말단에 위치하는 IKKβ 결합부위와 C-말단에 위치하는 leucine zipper 및 zinc finger 부위는 IKKγ와 Hsp90의 NF-κB에 대한 상호협력적 촉진작용에 필요하지 않았다. 또한 Hsp90에 의해 촉진된 세포내 pro-inflammatory cytokine들의 발현은 IKKγ에 의해 더욱 상승하였다. 이러한 결과로부터 Hsp90와 IKKγ의 상호작용을 차단한다면 NF-κB의 과다활성으로 인한 질병의 예방과 치료에 도움을 줄 수 있을 것으로 사료된다.

• 생명과학회지
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• 제16권1호
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• pp.1-5
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• 2006

본 연구는 Penibacillus polymyxa 균주의 CFTase 유전자를 결손 변이시킨 고효율 효소 CFT108을 이용하여 cyclofructan (CF)의 대량생산 조건을 검토하고 생산된 CF의 순수 분리 정제 공정을 개발하였다. CF의 대량생산 조건은 $2\%$의 inulin 기질과 40 unit/g inulin의 기질에서 3시간 반응시켰을 때 최대 생산량 9.5 g/l의 수율을 달성할 수 있었으며, 이때의 in-ulin의 CF 전환율은 $47.5\%$였다. 생산된 CF를 순수 분리 정제하기 위해서 CFTase 반응액 을 exoinulinase 1 unit/ml로 6시간 처리하여 미 반응 inulin을 단당화시켰으며, 유리된 fructose는 $3\%$ CaO로 $CO_2$가스 하에서 $80^{\circ}C$, 10분간 3회 흡착제거 시킴으로써 순수 정제하였다. 정제된 CF를 HPLC로 확인한 결과 정제도는 $95\%$ 이상이였으며, $CF_6,\;CF_7,\;CF_8$ 비율이 72 : 27 : 1 이였다.

• Journal of Microbiology and Biotechnology
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• 제16권9호
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• pp.1416-1421
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• 2006

We identified a gene encoding the N-acetylmuramoyl L-alanine amidase (amiB) of Vibrio anguillarum, which catalyzes the degradation of peptidoglycan in bacteria. The entire open reading frame (ORF) of the amiB gene was composed of 1,722 nucleotides and 573 amino acids. The deduced amino acid sequence of AmiB showed a modular structure with two main domains; an N-terminal region exhibiting an Ami domain and three highly conserved, continuously repeating LysM domains in the C-terminal portion. An amiB mutant was constructed by homologous recombination to study the biochemical function of the AmiB protein in V. anguillarum. Transmission electron microscopy (TEM) revealed morphological differences, and that the mutant strain formed trimeric and tetrameric unseparated cells, suggesting that this enzyme is involved in the separation of daughter cells after cell division. Furthermore, inactivation of the amiB gene resulted in a marked increase of sensitivity to oxidative stress and organic acids.

• Journal of Microbiology and Biotechnology
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• 제13권6호
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• pp.989-992
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• 2003

Recombinant human tissue plasminogen activator deletion mutein (Reteplase) is a clinically promising thrombolytic drug. Reteplase cDNA was subcloned into a bacteria expression system, and the resultant recombinant was biologically characterized. The Reteplase was expressed in Escherichia coli as an inclusion body, and the downstream processes of the Reteplase inclusion body included denaturation, renaturation, and purification. A protein disulfide isomerase (PDI) was used to assist the refolding of Reteplase, and it was found to increase the refolding rate from less than 2％ to more than 20％. The refolded Reteplase was purified through two chromatography steps, including lysine-coupled agarose affinity chromatography and then CM-sepharose cation-exchange chomatography. The purity of r-PA was analyzed by Western bolt analysis, and N-terminal amino acid and amino acid composition analyses confirmed the end-product. Reteplase showed higher thrombolytic potency in an animal thrombus model.

• Journal of Microbiology and Biotechnology
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• 제30권2호
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• pp.244-247
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• 2020

We have expressed extracellular poly(3-hydroxybutyrate) (PHB) depolymerase of Ralstonia pickettii T1 on the Escherichia coli surface using Pseudomonas OprF protein as a fusion partner by C-terminal deletion-fusion strategy. Surface display of depolymerase was confirmed by flow cytometry, immunofluorescence microscopy and whole cell hydrolase activity. For the application, depolymerase was used as an immobilized catalyst of enantioselective hydrolysis reaction for the first time. After 48 h, (R)-methyl mandelate was completely hydrolyzed, and (S)-mandelic acid was produced with over 99% enantiomeric excess. Our findings suggest that surface displayed depolymerase on E. coli can be used as an enantioselective biocatalyst.

• Journal of Microbiology and Biotechnology
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• 제30권2호
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• pp.216-225
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• 2020

An esterase gene, estA1, was cloned from Alteromonas sp. 39-G1 isolated from the Beaufort Sea. The gene is composed of 1,140 nucleotides and codes for a 41,190 Da protein containing 379 amino acids. As a result of a BLAST search, the protein sequence of esterase EstA1 was found to be identical to Alteromonas sp. esterase (GenBank: PHS53692). As far as we know, no research on this enzyme has yet been conducted. Phylogenetic analysis showed that esterase EstA1 was a member of the bacterial lipolytic enzyme family IV (hormone sensitive lipases). Two deletion mutants (Δ20 and Δ54) of the esterase EstA1 were produced in Escherichia coli BL21 (DE3) cells with part of the N-terminal of the protein removed and His-tag attached to the C-terminal. These enzymes exhibited the highest activity toward p-nitrophenyl (pNP) acetate (C₂) and had little or no activity towards pNP-esters with acyl chains longer than C₆. Their optimum temperature and pH of the catalytic activity were 45℃ and pH 8.0, respectively. As the NaCl concentration increased, their enzyme activities continued to increase and the highest enzyme activities were measured in 5 M NaCl. These enzymes were found to be stable for up to 8 h in the concentration of 3-5 M NaCl. Moreover, they have been found to be stable for various metal ions, detergents and organic solvents. These salt-tolerant and chemical-resistant properties suggest that the enzyme esterase EstA1 is both academically and industrially useful.

• 생명과학회지
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• 제20권10호
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• pp.1451-1457
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• 2010

Serotonin (5-hydroxytryptamine (5-HT))는 신경계의 세포-세포 간의 신호전달의 주요한 신경전달물질이다. 세포막에 존재하는 serotonin transporter (SERT)는 연접간격에 존재하는 5-HT를 세포 내로 재흡수 하여 세포외부의 5-HT 농도를 조절하지만 그 기전은 아직 밝혀지지 않았다. 본 연구에서는 yeast two-hybrid system을 사용하여 SERT의 C-말단이 protein kinase C-$\varepsilon$ (PKC-$\varepsilon$)과 특이적으로 결합함을 알았다. PKC-$\varepsilon$는 PKC의 isotype으로 calcium 비의존적이며 phorbol ester/diacylglycerol 민감성 serine/threonine kinase이다. $Na^+/Cl^-$ 의존성 SLC6 gene family의 다른 수송체는 PKC-$\varepsilon$과 결합하지 않았다. Deletion mutant들을 사용하여 SERT는 PKC-$\varepsilon$의 C-말단부위와 결합함을 알았으며, 또한 이 단백질간의 결합을 GST pull-down assay로 확인하였다. PKC-$\varepsilon$는 in vitro에서 SERT의 N-말단의 펩티드를 인산화시켰다. 이러한 결과들은 PKC-$\varepsilon$에 의한 SERT의 인산화가 세포막에 존재하는 SERT의 활성을 조절하는 역할을 할 가능성을 시사한다.

• Journal of Microbiology and Biotechnology
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• 제31권1호
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• pp.163-170
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• 2021

Enzyme replacement therapy for lysosomal storage diseases usually requires recombinant enzymes containing mannose-6-phosphate (M6P) glycans for cellular uptake and lysosomal targeting. For the first time, a strategy is established here for the in vitro mannosyl-phosphorylation of high-mannose type N-glycans that utilizes a recombinant Mnn14 protein derived from Saccharomyces cerevisiae. Among a series of N-terminal- or C-terminal-deleted recombinant Mnn14 proteins expressed in Pichia pastoris, rMnn1477-935 with deletion of N-terminal 76 amino acids spanning the transmembrane domain (46 amino acids) and part of the stem region (30 amino acids), showed the highest level of mannosyl-phosphorylation activity. The optimum reaction conditions for rMnn1477-935 were determined through enzyme assays with a high-mannose type N-glycan (Man8GlcNAc2) as a substrate. In addition, rMnn1477-935 was shown to mannosyl-phosphorylate high-mannose type N-glycans (Man7-9GlcNAc2) on recombinant human lysosomal alpha-glucosidase (rhGAA) with remarkably high efficiency. Moreover, the majority of the resulting mannosyl-phosphorylated glycans were bis-form which can be converted to bis-phosphorylated M6P glycans having a superior lysosomal targeting capability. An in vitro N-glycan mannosyl-phosphorylation reaction using rMnn1477-935 will provide a flexible and straightforward method to increase the M6P glycan content for the generation of "Biobetter" therapeutic enzymes.