• Title/Summary/Keyword: Site-specific mutagenesis

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Site-Specific Mutagenesis of the gshI Gene for Increasing the Activity of ${\gamma}$-Glutamylcysteine Synthetase in Escherichia coli K-12

  • Kwak, Joon-Hyeok;Nam, Yong-Suk;Lee, Se-Yong
    • BMB Reports
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    • v.31 no.3
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    • pp.254-257
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    • 1998
  • The gshI gene from the Escherichia coli K-12 strain codes for ${\gamma}-glutamylcysteine$ synthetase which mediates the rate-limiting step of glutathione biosynthesis. The isolated gshI gene from E. coli K-12 has an unusual translation initiation codon, UUG. The 494th amino acid is Ala rather than Gly which was found in a mutant strain E. coli B. In order to improve the translational rate of the gshI gene of E. coli K-12, the initiation codon, UUG, was changed to the usual AUG codon by the site-specific mutagenesis. This change has resulted in a 53% increase of ${\gamma}-glutamylcysteine$ synthetase activity. The enzyme activity was also improved by replacing $Ala^{494}$ with Val (A494V) or Leu (A494L). The replacement of $Ser^{495}$ with Thr (S495T) also resulted in a 62% increase of the enzyme activity. Therefore, the specific activity of ${\gamma}-glutamylcysteine$ synthetase was increased with the increasing chain length of the aliphathic amino acid at the site of the 494th amino acid (Ala<$Val{\leq}Leu$).

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Protein engineering을 위한 site-specific mutagenesis의 이용

  • 이세영
    • The Microorganisms and Industry
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    • v.14 no.1
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    • pp.22-28
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    • 1988
  • DNA 클로닝과 조작기술의 발전은 어떤 유전자의 특정한 위치에 선택적으로 돌연변이를 도입할 수 있는 site-specific mutagenesis 기술을 창출해 내었다. 이 기술로 DAN 염기의 치환, 결실, 삽입등을 클론된 유전자에 직접 도입할 수가 있게 되어 생체의 유전자 조작이나 유전자의 산물인 단백질의 구조와 기능을 의도적으로 변화시키는 protein engineering에 광범위하게 이용되고 있다. Protein engineering은 주로 단백질의 촉매 및 생리활성의 증가, 효소의 특성및 기질 특이성의 변화, 단백질 구조의 안정화 및 내염성 증가, 분자량의 감소, 효소및 생리활성 단백질의 구조의 안정화및 내열성 증가 등에 활용되고 있으며 산업적 유용성이 큰새로운 단백질의 창조에도 기여할 것으로 기대를 모으고 있다. Site-specific mutagenesis 기술로 현재 가장 널리 이용되는 것이 in vitro상에서 수행하는 oligonucleotide-directed site specific mutagenesis이다. 이 방법은 생화학적으로 합성한 특정한 염기서열을 가진 oligonucleotide들을 일종의 mutagen으로 사용하거나 효소적 DNA 합성을 위한 primer로 사용하여 클론된 DNA의 염기서열을 선택적으로 개조하거나 혹은 다른 조작을 하는 것이다. 여기서는 돌연변이율을 높이는 여러가지 개량된 방법들이 나왔으며 그중의 몇가지를 소개하였다.

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Expression of Carboxypeptidase Z cDNA from Absidia zychae in saccharomyces cerevisiae and its characteristics (Saccharomyces cerevisiae에서 Absidia zychae 의 Carboxypeptidase A cDNA 의 발현과 특성)

  • 이병로;김종화
    • Microbiology and Biotechnology Letters
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    • v.23 no.2
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    • pp.150-155
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    • 1995
  • Carboxypeptidase Z(CPZ) cDNA of Absidia zychae was experssed in Saccharomyces cerevisiae. The expressed CPZ(YCPZ) was secreted about 30 mg/l into the medium and has a little higher molecular weight than the wild type CPZ in SDS-PAGE. By the result of N-terminal amino acid sequencing, YCPZ has additional 15 amino acids residues in N-terminus of CPZ. But YCPZ shows no difference with CPZ in enzyme activity and substrate specificity. For the identification of processing mechanism of YCPZ, 36-Arg was changed to 36-Thr by site specific mutagenesis. Mutant YCPZ does not processed at 36-Thr. It was, therefore, concluded that the YCPZ was processed by KEX2. According to endo F treatment, high amount of carbohydrate was N-glycosylated in YCPZ.

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Site-Specific Mutagenesis on the 32-T and 39-T of E. coli $tRNA^{phe}$ Gene (E. coli $tRNA^{phe}$ 유전자의 32-T와 39-T 염기의 부의 특이적 돌연변이)

  • 김익영;이세영
    • Korean Journal of Microbiology
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    • v.27 no.3
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    • pp.176-180
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    • 1989
  • There are three pseudourdine ($Psi$)bases in the E. coli $tRNA^{phe}$ In order to study the function of the pseudouridine bases in the $tRNA^{phe}$, changes of bases $tRNA^{phe}$ gene to other bases were undertaken by the site-specific mutagenesis. Site-specific mutagenesis of T in the pheW gene, a $tRNA^{phe}$ gene of E. coli, corresponding to the baseat the No.32 position to C and also T corresponding to the base at the No.39 position to C were performed using Kunkel's uracil-containing template method. Identification of mutants were undertaken by the KNA sequencing techniques of the mutated pheW genes and activities of the mutated pheW genes complementing to E. coli NP37 mutant($pheS^{-ts}$) using the recombinant plasmid containing the mutated genes. Neither NP37 harboring pheW gene mutated at No.32 position nor NP37 harboring pheW gene mutated at No.39 position can be grown at non-permissive temperature. The result means that both mutated pheW genes can not complement to E. coli NP37, and that the pseudouridine bases are essential to the activity of the E. coli $tRNA^{phe}$ in vivo.

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Structural Roles of Cysteine 50 and Cysteine 230 Residues in Arabidopsis thaliana S-Adenosylmethionine Decarboxylase

  • Park, Sung-Joon;Cho, Young-Dong
    • BMB Reports
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    • v.35 no.2
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    • pp.178-185
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    • 2002
  • The Arabidopsis thaliana S-Adenosylmethionine decarboxylase (AdoMetDC) cDNA ($GenBank^{TM}$ U63633) was cloned. Site-specific mutagenesis was performed to introduce mutations at the conserved cysteine $Cys^{50}$, $Cys^{83}$, and $Cys^{230}$, and $lys^{81}$ residues. In accordance with the human AdoMetDC, the C50A and C230A mutagenesis had minimal effect on catalytic activity, which was further supported by DTNB-mediated inactivation and reactivation. However, unlike the human AdoMetDC, the $Cys^{50}$ and $Cys^{230}$ mutants were much more thermally unstable than the wild type and other mutant AdoMetDC, suggesting the structural significance of cysteines. Furthermore, according to a circular dichroism spectrum analysis, the $Cys^{50}$ and $Cys^{230}$ mutants show a higher a-helix content and lower coiled-coil content when compared to that of wild type and the other mutant AdoMetDC. Also, the three-dimensional structure of Arabidopsis thaliana AdoMetDC could further support all of the data presented here. Summarily, we suggest that the $Cys^{50}$ and $Cys^{230}$ residues are structurally important.

Site-speci fic Inactivation o meso-Diaminopimelate-dehydrogenase Gene (ddh) in a Lysine-producing Brevibacterium lactofementum. (Brevibacterium lactofermentum 에서 meso-Diaminopimelate-dehydrogenase Gene (ddh)의 Site-specific Inactivation)

  • 김옥미;박선희;이갑랑
    • Microbiology and Biotechnology Letters
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    • v.26 no.5
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    • pp.387-392
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    • 1998
  • Brevibacterium lactofermentum, a gram-positive bacteria, has both the diaminopimelate (DAP) pathway and meso-DAP-dehydrogenase (DDH) pathway for L-lysine biosynthesis. To investigate importance of DDH pathway and the related ddh gene in lysine production, we introduced site-specific mutagenesis technique. A 300 bp DNA fragment central to the meso-DAP-dehydrogenase gene (ddh) of B. lactofermentum was used to inactive chromosomal ddh gene via homologous recombination. Southern hybridization analysis confirmed that the chromosomal ddh gene was disrupted by the vector sequence. The B. lactofementum ddh mutant obtained have an inactive DDH pathway. The results reveal that inactivation of the ddh gene in B. lactofermentum leads to dramatic reduction of lysine production as well as decrease of the growth rate, indicating that the DDH pathway is essential for high-level lysine production as well as biosynthesis of meso-DAP.

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Oligonucleotide의 합성과 이용 <생명공학의 약학적 응용>

  • 나도선
    • YAKHAK HOEJI
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    • v.29 no.6
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    • pp.109-117
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    • 1985
  • 합성 DNA는 분자 생물학의 모든 분야의 연구에 사용될 수 있으며 앞으로도 그 이용도는 더욱 증가할 것으로 전망된다. 합성 기술의 발달로 생리활성을 가진 인조 유전자를 제조하는 것이 가능해졌으며 또한 다른 방법으로는 어려운 유전자의 분리와 cloning, site specific mutagenesis, 질병의 진단, 유전자의 구조 및 기능의 연구등 수많은 분야의 연구에 이용되고 있다. 본 고에서는 현재 여러 군데 분자 생물학 연구실에서 성공적으로 사용되고 있는 자동 합성기에 의한 phosphite합성법의 기초 이론과 합성된 oligonucleotide의 정제법에 대하여 간단히 서술하고 그 응용 방법에 대하여 논하고자 한다.

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Determination of Active Site in PRD1 DNA Polymerase by Site-specific Mutagenesis (Site-specific Mutagenesis에 의한 PRD1 DNA Polymerase의 활성부위 결정)

  • 황정원;정구홍
    • Korean Journal of Microbiology
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    • v.29 no.4
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    • pp.209-214
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    • 1991
  • The PRD1 DNA polymerase is a small multi-functional enzyme containing conserved amino acid sequences shared by family B DNA polymerases. Thus the PRD1 DNA polymerase provides an useful model system with which to study structure-functional relationships of DNA polymerase molecules. In order to investigate the functional and structural roles of the highly conserved amino acid sequences, we have introduced three mutations into a conserved amino acid of the PRD1 DNA polymerase. Genetic complememtation study indicated that each mutation inactivated DNA polymerase catalytic activity.

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유전자적중을 위한 상동유전자재조합 기술의 개발

  • 양정희;장석민;나루세겐지;심호섭;김남형;박창식;진동일
    • Proceedings of the KSAR Conference
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    • 2002.06a
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    • pp.96-96
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    • 2002
  • 상동유전자 재조합기술을 myostatin 유전자에 적용하기 위해 돼지 골격에 붙어 있는 근육으로부터 RNA를 추출하였고 돼지 Myostain Exon 3 부위의 specific primer를 제작하여 RT-PCR 을 수행 한 후 증폭된 342bp DNA 를 추출하여 T vector 에 ligation한 후 sequencing을 실시하여 돼지 genomic DNA 에서 Myostatin gene 의 Exon 3 부위와 100% match 되는 것을 확인하였다. (omitted)

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