• Journal of Microbiology and Biotechnology
• /
• 제19권10호
• /
• pp.1085-1091
• /
• 2009

A phytase with high activity at low temperatures has great potential for feed applications, especially in aquaculture. Therefore, this study used a degenerate PCR and TAIL PCR to clone a phytase gene from Erwinia carotovora var. carotovota, the cause of soft rot of vegetables in the ground or during cold storage. The full-length 2.5-kb fragment included an open reading frame of 1,302 bp and encoded a putative phytase of 45.3 kDa with a 50% amino acid identity to the Klebsiella pneumoniae phytase. The phytase contained the active site RHGXRXP and HD sequence motifs that are typical of histidine acid phosphatases. The enzyme was expressed in Escherichia coli, purified, and displayed the following characteristics: a high catalytic activity at low temperatures (retaining over 24% activity at $5^{\circ}C$) and remarkably thermal lability (losing >96% activity after incubation at $60^{\circ}C$ for 2 min). The optimal phytase activity occurred at pH 5.5 and ${\sim}49^{\circ}C$, and the enzyme activity rapidly decreased above $40^{\circ}C$. When compared with mesophilic counterparts, the phytase not only exhibited a high activity at a low temperature, but also had a low $K_m$ and high $k_{cat}$. These temperature characteristics and kinetic parameters are consistent with low-temperature-active enzymes. To our knowledge, this would appear to be the first report of a low-temperature-active phytase and its heterogeneous expression.

• Journal of Microbiology and Biotechnology
• /
• 제20권12호
• /
• pp.1735-1743
• /
• 2010

The full-length genes gyrB (2,415 bp), parC (2,277 bp), and parE (1,896 bp) in Edwardsiella tarda were cloned by PCR with degenerate primers based on the sequence of the respective quinolone resistance-determining region (QRDR), followed by elongation of 5' and 3' ends using cassette ligation-mediated PCR (CLMP). Analysis of the cloned genes revealed open reading frames (ORFs) encoding proteins of 804 (GyrB), 758 (ParC), and 631 (ParE) amino acids with conserved gyrase/topoisomerase features and motifs important for enzymatic function. The ORFs were preceded by putative promoters, ribosome binding sites, and inverted repeats with the potential to form cruciform structures for binding of DNA-binding proteins. When comparing the deduced amino acid sequences of E. tarda GyrB, ParC, and ParE with those of the corresponding proteins in other bacteria, they were found to be most closely related to Escherichia coli GyrB (87.6% identity), Klebsiella pneumoniae ParC (78.8% identity), and Salmonella Typhimurium ParE (89.5% identity), respectively. The two topoisomerase genes, parC and parE, were found to be contiguous on the E. tarda chromosome. All 18 quinolone-resistant isolates obtained from Korea thus far did not contain subunit alternations apart from a substitution in GyrA (Ser83$\rightarrow$Arg). However, an alteration in the QRDR of ParC (Ser84$\rightarrow$Ile) following an amino acid substitution in GyrA (Asp87$\rightarrow$Gly) was detected in E. tarda mutants selected in vitro at $8{\mu}g/ml$ ciprofloxacin (CIP). A mutant with a GyrB (Ser464$\rightarrow$Leu) and GyrA (Asp87$\rightarrow$Gly) substitution did not show a significant increase in the minimum inhibitory concentration (MIC) of CIP. None of the in vitro mutants exhibited mutations in parE. Thus, gyrA and parC should be considered to be the primary and secondary targets, respectively, of quinolones in E. tarda.

• 생명과학회지
• /
• 제13권6호
• /
• pp.879-888
• /
• 2003

추에서 항균 phytoalexin으로 알려진 capsidiol의 생합성을 촉매하는 5-epi-aristolochene hydroxylase는 cytochrome P450 (P450) 억제제인 ancymidol과 ketocornazol에 의해 그 활성이 특이적으로 억제되어, 이 효소가 P450계 효소임을 알 수 있었다. P450 효소가 공통으로 보유하는 염기서열을 지닌 primer를 이용하여 RT-PCR과 cDNA screening을 실시한 결과 고추배양세포에서 elicitor 처리에 의해 강하게 유도되는 cDNA (P450Hy01)를 cloning하였다. 배양세포에 cellulase, arachidonic acid, jasmonic acid, 자외선 등을 처리하여 capsidiol을 생합성하는 량과 P450Hy01 mRNA의 발현정도는 밀접한 유사성이 있었다. P450Hy01의 염기서열은 담배에서 밝혀진 5-epi-aristolochene-1,3-hydroxylase와 98%의 유사성이 있었으며, P450 효소가 공통으로 지니는 heme-binding domain인 FxxGxRxCxG를 보유하고 있었다 이러한 결과는 본 연구에서 cloning된 P450Hy01이 고추의 세포에서 capsidiol의 생합성을 촉매하는 5-epi-aristolochene hydroxylase 효소를 coding 하고 있음을 시사한다.

• Plant Biotechnology Reports
• /
• 제5권4호
• /
• pp.331-344
• /
• 2011

The well-conserved NBS domain of resistance (R) genes cloned from many plants allows the use of a PCR-based approach to isolate resistance gene analogs (RGAs). In this study, we isolated an RGA (CapRGC) from Capsicum annuum "CM334" using a PCR-based approach. This sequence encodes a protein with very high similarity to Rx genes, the Potato Virus X (PVX) R genes from potato. An evolutionary analysis of the CapRGC gene and its homologs retrieved by an extensive search of a Solanaceae database provided evidence that Rx-like genes (eight ESTs or genes that show very high similarity to Rx) appear to have diverged from R1 [an NBS-LRR R gene against late blight (Phytophthora infestans) from potato]-like genes. Structural comparison of the NBS domains of all the homologs in Solanaceae revealed that one novel motif, 14, is specific to the Rx-like genes, and also indicated that several other novel motifs are characteristic of the R1-like genes. Our results suggest that Rx-like genes are ancient but conserved. Furthermore, the novel conserved motifs can provide a basis for biochemical structural. function analysis and be used for degenerate primer design for the isolation of Rx-like sequences in other plant species. Comparative mapping study revealed that the position of CapRGC is syntenic to the locations of Rx and its homolog genes in the potato and tomato, but cosegregation analysis showed that CapRGC may not be the R gene against PVX in pepper. Our results confirm previous observations that the specificity of R genes is not conserved, while the structure and function of R genes are conserved. It appears that CapRGC may function as a resistance gene to another pathogen, such as the nematode to which the structure of CapRGC is most similar.

• KSBB Journal
• /
• 제22권1호
• /
• pp.7-15
• /
• 2007

진균류 추출물로부터 신규 멜라닌 분해효소의 분리 및 분해능 test는 멜라닌 분해효소의 균사체 배양 상등액으로 분비 생산됨을 분해능 테스트를 통하여 확인하였고, 이 분해 효소에 의한 멜라닌 분해반응은 pH 7에서 가장 높고, 30$^{\circ}C$에서 가장 안정함을 확인하였다. 멜라닌 분해 효소의 characterization은 2D-gel을 이용하여 멜라닌 분해효소 중 한 가지 효소의 pI값이 약 6.5이고 Molecular weight는 약 54-57 kDa임을 알 수 있었고, 정제된 멜라닌 분해 효소의 전체적인 단백질 및 유전자 서열을 분석하여 degenerate primer를 합성하였으며, RT-PCR 법을 이용하여 유전자를 확보하였다. 멜라닌 분해효소 생산을 위한 진균류의 배양방법 확립은 멜라닌 분해효소가 최대 활성을 갖는 배지 조건은 ammonium tartrate 0.4% : glucose 2% 배지에 yeast extract를 0.1%를 첨가한 배지임을 확인하였고, 진군류의 최적 배양온도는 24-26$^{\circ}C$였으며, 이 때 건조 균체 중량으로 약 6 g/L의 균체를 얻을 수 있었다. 또한 진균류 성장의 최적 pH는 약 5.5로서 이 경우 건조균체중량이 약 6.6 g/L였다. 정제공정은 최적화를 통하여 멜라닌 분해효소의 정제 순도 90% 이상의 정제공정을 확립하였다. Scale-up은 5 L fermenter를 이용한 기초 배양공정을 확립하여 500 L fermenter로의 경제성 있는 scale up에 성공하였고, 이 때 건조균체중량 약 14.5 g/L의 진균류를 얻었으며, 배지 중에 분비 생산된 melanin 분해효소의 양이 300 mg/L에 달하였다. 멜라닌 분해효소의 formulation은 멜라닌 분해효소를 효율적으로 피부로 전달시키기 위하여 50-100 nm 크기로 encapsulation을 실시하여 70 nm, 100 nm size의 nano capsule을 얻었다. 본 연구는 tyrosinase 저해제가 갖는 부작용이 없어 생체 친화적 물질에 의한 부작용 감소 효과가 기대되며, 독자적 기술에 의한 고부가 미백용 화장품 원료 확보로 새로운 기능에 의한 신규시장 창출이 가능하여 미백용 기능성 화장품 원료로서 고부가 화장품에 사용되어 수입대체효과 및 기업의 매출증대 효과가 있을 것으로 기대되어진다.

• 한국미생물·생명공학회지
• /
• 제44권3호
• /
• pp.317-323
• /
• 2016

본 연구에서는 C. fermentati SI가 생산하는 isoflavone 배당체 가수분해 효소를 클로닝하여 염기 서열을 밝힌 뒤 P. pastoris X-33에 형질전환하여 재조합 효소의 과발현을 시켰고, 또한 재조합 isoflavone 가수분해 효소의 효소학적 특성을 조사하였다. 재조합 isoflavone 가수분해 효소의 분자량은 약 50.4 kDa이었으며, Meyerozyma guilliermondii ATCC 6260의 exo-1,3-β-glucanase와 96%로 가장 높은 homology를 나타내었다. exo-1,3-β-glucanase의 ORF는 pPICZA 벡터로 클로닝 후 P. pastoris X-33으로 형질전환을 하였으며, His6-tag을 이용하여 효소를 정제하였다. 정제된 효소는 citrate phosphate buffer pH 4.5에서 최적 활성을 나타내었으며, 효소의 최적 활성 온도는 40℃로 나타났다. 40℃이상에서는 효소의 활성이 급격하게 감소함을 확인 하였으며, pH 안정성을 조사한 결과 비교적 넓은 범위인 4−8 사이에서 80%이상의 활성을 유지하였다. 따라서, 재조합 효소의 과발현을 통해 isoflavone aglycone의 효율적인 생산에 이용할 수 있을 것으로 사료된다.

• 미생물학회지
• /
• 제44권1호
• /
• pp.74-79
• /
• 2008

L-ascorbic acid (AA)의 2번 위치의 수산기에 부위 특이적 활성을 갖는 Paenibacillus sp. JB-13 유래의 cyclodextrin glucanotransferase (CGTase, EC 2.4.1.19) 유전자(cgt gene)를 pEXP7 발현 vector에 클로닝하여 재조합 균주를 구축하였다. 재조합 균주의 CGTase생산 최적 조건을 검토하여 본 결과 LB 배지에 0.5% glucose, 3.0% polypeptone, 0.3% $K_2HPO_4$, 0.5% NaCl이 되도록 추가하고, 초기 pH 7.0, 접종량 2%, 통기량 0.1 vvm, 배양 온도 $37^{\circ}C$, 배양 시간 14시간의 조건에서 최대 활성을 나타내었다. 재조합 균주와 기존 균주의 CGTase 활성을 비교한 결과 재조합 균주는 배양 14시간째 640 units/ml의 활성을 가져 기존 균주에 비해 70%의 활성을 나타내지만 배양 시간을 1/4로 단축시킬 수 있다는 이점이 있음을 확인하였다. 재조합 균주가 생산한 CGTase를AA-2G합성에 적용하여 AA-2G를 합성하고 HPLC로 분석한 결과 단일 peak를 확인할 수 있었고 ${\alpha}$-glucosidase를 처리하여 확인한 결과 AA와 glucose로 분리됨을 확인할 수 있었다.

• Journal of Microbiology and Biotechnology
• /
• 제18권7호
• /
• pp.1290-1297
• /
• 2008

To investigate the diversities of Accumulibacter phosphatis and its polyhydroxyalkanoate (PHA) synthase gene (phaC) in enhanced biological phosphorus removal (EBPR) sludge, an acetate-fed sequencing batch reactor was operated. Analysis of microbial communities using fluorescence in situ hybridization and 16S rRNA gene clone libraries showed that the population of Accumulibacter phosphatis in the EBPR sludge comprised more than 50% of total bacteria, and was clearly divided into two subgroups with about 97.5% sequence identity of the 16S rRNA genes. PAO phaC primers targeting the phaC genes of Accumulibacter phosphatis were designed and applied to retrieve fragments of putative phaC homologs of Accumulibacter phosphatis from EBPR sludge. PAO phaC primers targeting $G_{1PAO},\;G_{2PAO},\;and\;G_{3PAO}$ groups produced PCR amplicons successfully; the resulting sequences of the phaC gene homologs were diverse, and were distantly related to metagenomic phaC sequences of Accumulibacter phosphatis with 75-98% DNA sequence identities. Degenerate NPAO (non-PAO) phaC primers targeting phaC genes of non-Accumulibacter phosphatis bacteria were also designed and applied to the EBPR sludge. Twenty-four phaC homologs retrieved from NPAO phaC primers were different from the phaC gene homologs derived from Accumulibacter phosphatis, which suggests that the PAO phaC primers were specific for the amplification of phaC gene homologs of Accumulibacter phosphatis, and the putative phaC gene homologs by PAO phaC primers were derived from Accumulibacter phosphatis in the EBPR sludge. Among 24 phaC homologs, a phaC homolog (GINPAO-2), which was dominant in the NPAO phaC clone library, showed the strongest signal in slot hybridization and shared approximately 60% nucleotide identity with the $G_{4PAO}$ group of Accumulibacter phosphatis, which suggests that GINPAO-2 might be derived from Accumulibacter phosphatis. In conclusion, analyses of the 16S rRNA and phaC genes showed that Accumulibacter phosphatis might be phylogenetically and metabolically diverse.

• Molecules and Cells
• /
• 제27권4호
• /
• pp.423-428
• /
• 2009

Superoxide dismutases (SODs) constitute the first line of cellular defense against oxidative stress in plants. SODs generally occur in three different forms with Cu/Zn, Fe, or Mn as prosthetic metals. We cloned the full-length cDNA of the Thellungiella halophila Cu/Zn-SOD gene ThCSD using degenerate RT-PCR and rapid amplification of cDNA ends (RACE). Sequence analysis indicated that the ThCSD gene (GenBank accession number EF405867) had an open reading frame of 456 bp. The deduced 152-amino acid polypeptide had a predicted molecular weight of 15.1 kDa, an estimated pI of 5.4, and a putative Cu/Zn-binding site. Recombinant ThCSD protein was expressed in Escherichia coli and assayed for SOD enzymatic activity in a native polyacrylamide gel. The SOD activity of ThCSD was inactivated by potassium cyanide and hydrogen peroxide but not by sodium azide, confirming that ThCSD is a Cu/Zn-SOD. Northern blotting demonstrated that ThCSD is expressed in roots, stems, and leaves. ThCSD mRNA levels increased by about 30-fold when plants were treated with sodium chloride (NaCl), abscisic acid (ABA), and indole-acetic acid (IAA) and by about 50-fold when treated with UVB light. These results indicate that ThCSD is involved in physiological pathways activated by a variety of environmental conditions.