• Journal of Microbiology and Biotechnology
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• v.9 no.5
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• pp.631-636
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• 1999

The thermostable endo-chitosanase gene from the isolated strain Bacillus sp. KFB-C108 was identified on the basis of a phylogenetic analysis of the 16S rRNA gene sequence, and was cloned into plasmid pUCl8 using E. coli $DH5\alpha$ as the host strain. Positive clones carrying recombinant plasmids (pKCHO I and pKCHO II) containing chitosanase activity were selected using the direct activity staining method. Detailed physical maps showed the two plasmid inserts were identical except that the KCHO II insert (2.6 kb) was 1.8 kb smaller than that of the KCHO I. The recombinant plasmids were analyzed to determine the essential region for chitosanase activity, and a 1.3-kb fragment (KCHO-6) was subcloned into pTrc99A using the EcoRI and BamHI sites to construct pTrc99A/KCHO-6(pTrEB13). The resulting plasmid exerted high chitosanase activity upon transformation of E. coli $DH5{\alpha}cells$, overproducing about 20 times more in the cloned cells than in the wild-type cells. The cloned chitosanase protein exhibited the same molecular weight and catalytic activity similar to those of Bacillus sp. KFB-C108. The cloned enzyme was an endo-type that produced a chitosan tetramer as the major reaction product; however, it produced no monomers or dimers.

• Journal of Microbiology and Biotechnology
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• v.24 no.4
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• pp.483-488
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• 2014

In order to improve the expression of heat-resistant xylanase XYNB from Aspergillus niger SCTCC 400264, XynB has been cloned into Pichia pastoris secretary vector pPIC9K. The XynB production of recombinant P. pastoris was four times that of E. coli, and the $V_{max}$ and specific activity of XynB reached $2,547.7{\mu}mol/mg$ and 4,757 U/mg, respectively. XynB still had 74% residual enzyme activity after 30 min of heat treatment at $80^{\circ}C$. From the van der Waals force analysis of XYNB (ACN89393 and AAS67299), there is one more oxygen radical in AAS67299 in their catalytic site, indicating that the local cavity is much more free, and it is more optimal for substrate binding, affinity reaction, and proton transfer, etc, and eventually increasing enzyme activity. The H-bonds analysis of XYNB indicated that there are two more H-bonds in the 33rd Ser of XYNB (AAS67299) than in the 33rd Ala(ACN89393 ), and two H-bonds between Ser70 and Asp67.

• Journal of Microbiology and Biotechnology
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• v.8 no.6
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• pp.560-567
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• 1998

We have found that Thermoactinomyces vulgaris KFB-Cl00 produces a chitinase. The optimum temperature and pH of the enzyme activity were $55^{\circ}C$ and 6.5. The enzyme was stable after heat treatment at $80^{\circ}C$ for 30 min and stable in acidic and basic conditions (PH 6.0~11.0). The thermostable endo-chitinase from Thermoactinomyces vulgaris KFB-C100 was cloned into the plasmid pBR322 by using E. coli DH5$\alpha$ as a host strain. The positive clone carrying a recombinant plasmid (PKCHI23) with a 4.1-kb fragment containing the chitinase gene was found. The recombinant plasmid was analyzed to determine the essential region for chitinase activity and obtained a 2.3-kb fragment, which was sub cloned into pTrc99A using the PstI and SalI sites to construct pTrc99A/pKCHI23-3. The resulting plasmid exerted high chitinase activity upon transformation of E. coli XL1-Blue cells. Chitinase was overproduced 14 times more in the clone cells than in the wild-type cells and the enzyme was purified to homogeneity. The purified enzyme showed the similar properties as the native chitinase from T. vulgaris in terms of molecular weight and substrate specificity. The catalytic action of the cloned enzyme was an endo type, producing chitobiose as a major reaction product.

• The Journal of Korean Society of Virology
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• v.28 no.3
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• pp.233-245
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• 1998

The gene encoding F protein of CBP-1 strain, a heat-stable Newcastle disease virus (NDV) isolated from the diseased pheasants in Korea, was characterized by reverse transcription-polymerase chain reaction (RT-PCR), nucleotide and amino acid sequences. Virus RNA was prepared from the chorioallatoic fluid infected with NDV CBP-1 virus and cDNA was amplified by RT-PCR, cloned and sequenced to analyze. The PCR was sensitive as to detect the virus titer above $2^5$ hemagglutination unit. 1.7kb (1,707bp) size of the cDNA was amplified and cloned into BamHI site of pVL1393 Baculo transfer vector. The nucleotide sequences for F protein were determined by dye terminator cyclic sequencing using four pairs of primers, and 553 amino acid sequences were predicted. In comparison of the nucleotide sequence of F gene of CBP-1 with those of other NDV strains, the homology revealed 88.8%, 98.5% and 98.7% with Kyojungwon (KJW), Texas GB and Beaudette C strains, respectively. As the deduced 553 amino acid sequences of F protein of CBP-1 were compared with those of other NDV strains, the homology appeared 89.9%, 98.7% and 98.9% with KJW, Texas GB and Beaudette C strains, respectively. The putative protease cleavage site (112-116) was R-R-Q-K-R, indicating that CBP-1 strain is velogenic type. The amino acid sequences include 6 sites of N-asparagine-linked glycosylation and 13 cysteine residues. These data indicate that the genotype of CBP-1 strain is more closely associated with the strains of Texas GB and Beaudette C than KJW strain.

• Microbiology and Biotechnology Letters
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• v.17 no.4
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• pp.334-342
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• 1989

The Bacillus stearothermophilus cdd gene encoding cytidine deaminase (cytidine/2'-deoxycytidine aminohydrolase; EC 3.5.4.5) was isolated through shot gun cloning by oomplementation of an E. coli cdd mutation. Primarily 3.0 kbp of the exogenote was cloned into the Pstl site of pBR322 (pJSC101). By subsequent deletion and subcloning from the insert of pJSC101 with cdd$^+$ and tetracycline resistancy, about 1.35 kbp of the EcoRI$_1$/PstI$_2$ fragment containing the cdd gene was isolated as pJSC201. The minicell experiment revealed a molecular mass of 33,000 dalton for polypeptide from the cloned DNA fragment complementing the cdd gene. From the lacZ fusion of 550 bp fragment of the EcoRI$_1$/AuaI as a putative promoter region, the transcription direction of the cdd gene on pJSC201 is from EcoRI towards the PstI sites, When the cdd gene was expressed in B. subtilis ED4O (cdd$^-$, pyr$^-$) by transformation with the E. coli-B. subtilis shuttle vector, the gene expression occured more efficiently than in E. coli and the gene appears to be stably maintained in B. subtitis as well as in E. coli.

• Molecules and Cells
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• v.42 no.6
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• pp.460-469
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• 2019

Bacterial ${\alpha}-type$ carbonic anhydrase (${\alpha}-CA$) is a zinc metalloenzyme that catalyzes the reversible and extremely rapid interconversion of carbon dioxide to bicarbonate. In this study, we report the first crystal structure of a hyperthermostable ${\alpha}-CA$ from Persephonella marina EX-H1 (pmCA) in the absence and presence of competitive inhibitor, acetazolamide. The structure reveals a compactly folded pmCA homodimer in which each monomer consists of a 10-stranded ${\beta}-sheet$ in the center. The catalytic zinc ion is coordinated by three highly conserved histidine residues with an exchangeable fourth ligand (a water molecule, a bicarbonate anion, or the sulfonamide group of acetazolamide). Together with an intramolecular disulfide bond, extensive interfacial networks of hydrogen bonds, ionic and hydrophobic interactions stabilize the dimeric structure and are likely responsible for the high thermal stability. We also identified novel binding sites for calcium ions at the crystallographic interface, which serve as molecular glue linking negatively charged and otherwise repulsive surfaces. Furthermore, this large negatively charged patch appears to further increase the thermostability at alkaline pH range via favorable charge-charge interactions between pmCA and solvent molecules. These findings may assist development of novel ${\alpha}-CAs$ with improved thermal and/or alkaline stability for applications such as $CO_2$ capture and sequestration.

• Journal of Microbiology and Biotechnology
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• v.17 no.1
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• pp.123-129
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• 2007

The trehalose $({\alpha}-D-glucopyranosyl-[1,1]-{\alpha}-D-glucopyranose)$ biosynthesis genes MhMTS and MhMTH, encoding a maltooligosyltrehalose synthase (MhMTS) and a maltooligosyltrehalose trehalohydrolase (MhMTH), respectively, have been cloned from the hyperthermophilic archaebacterium Metallosphaera hakonesis. The ORF of MhMTS is 2,142 bp long, and encodes 713 amino acid residues constituting a 83.8 kDa protein. MhMTH is 1,677 bp long, and encodes 558 amino acid residues constituting a 63.7 kDa protein. The deduced amino acid sequences of MhMTS and MhMTH contain four regions highly conserved for MTSs and three for MTHs that are known to constitute substrate-binding sites of starch-hydrolyzing enzymes. Recombinant proteins obtained by expressing the MhMTS and MhMTH genes in E. coli catalyzed a sequential reaction converting maltooligosaccharides to produce trehalose. Optimum pH of the MhMTS/MhMTH enzyme reaction was around 5.0 and optimum temperature was around 70 C. Trehalose-producing activity of the MhMTS/ MhMTH was notably stable, retaining 80% of the activity after preincubation of the enzyme mixture at $70^{\circ}C$ for 48 h, but was gradually abolished by incubating at above $85^{\circ}C$. Addition of thermostable $4-{\alpha}-glucanotransferase$ increased the yield of trehalose production from maltopentaose by 10%. The substrate specificity of the MhMTS/MhMTH-catalyzed reaction was extended to soluble starch, the most abundant maltodextrin in nature.