• Journal of Microbiology
• /
• v.37 no.2
• /
• pp.102-110
• /
• 1999

Genetic determinant for the secondary metabolism was studied in heterologous expression in Streptomyces lividans TK-24 using Streptomyces griseus ATCC 10137 as a donor strain. Chromosomal DNA of S. griseus was ligated into the high-copy number Streptomyces shuttle plasmid, pWHM3, and introduced into S. lividans TK-24. A plasmid clone with 4.3-kb BamHI DNA of S. griseus (pMJJ201) was isolated by detecting for stimulatory effect on actinorhodin production by visual inspection. The 4.3-kb BamHI DNA was cloned into pWHM3 under the control of the strong constitutive ermEp promoter in both directions (pMJJ202); ermEp promoter-mediated transcription for coding sequence reading right to left: pMJJ203; ermEp promoter-mediated transcription for coding sequence reading left to right) and reintroduced into S. lividans TK-24. The production of actinorhodin was markedly stimulated due to introduction of pMJJ202 on regeneration agar. The introduction of pMJJ202 also stimulated production of actinorhodin and undecylproidigiosin in submerged culture employing the actinorhodin production medium. Introduction of pMJJ203 resulted in a marked decrease of production of the two pigments. Nucleotide sequence analysis of the 4.3-kb region revealed three coding sequences: two coding sequences reading left to right, ORF1 and ORF2, one coding sequence reading right to left, ORF3. Therefore, it was suggested that the ORF3 product was responsible for the stimulation of antibiotic production. The C-terminal region of ORF3 product showed a local alignment with Myb-related transcriptional factors, which implicated that the ORF3 product might be a novel DNA-binding protein related to the regulation of secondary metabolism in Streptomyces.

• Journal of Microbiology and Biotechnology
• /
• v.16 no.6
• /
• pp.952-960
• /
• 2006

As a unicellular green alga that possesses many of the metabolic pathways present in higher plants, Chlorelia offers many advantages for expression of heterologous proteins. Since strong and constitutive promoters are necessary for efficient expression in heterologous expression systems, the development of such promoters for use in the Chlorella system was the aim of this study. Proteins encoded by the early genes of algal viruses are expressed before viral replication, probably by the host transcriptional machinery, and the promoters of these genes might be useful for heterologous expression in Chlorella. In this study, putative promoter regions of DNA polymerase, ATP-dependent DNA ligase, and chitinase genes were amplified from eight Korean Chlorella virus isolates by using primer sets designed based on the sequence of the genome of PBCV-1, the prototype of the Phycodnaviridae. These putative promoter regions were found to contain several cis-acting elements for transcription factors, including the TATA, CAAT, NTBBF1, GATA, and CCAAT boxes. The amplified promoter regions were placed into Chlorella transformation vectors containing a green fluorescence protein (GFP) reporter gene and the Sh ble gene for phleomycin resistance. C. vulgaris protoplasts were transformed and then selected with phleomycin. The GFP fluorescence intensities of cells transformed with chitinase, DNA polymerase, and DNA ligase gene promoter-GFP fusion constructs were 101.5, 100.8, and 95.8%, respectively, of that of CaMV 35S-GFP-transformed Chlorella cells. These results demonstrate that these viral promoters are active in transformed Chlorella.

• Biotechnology and Bioprocess Engineering:BBE
• /
• v.5 no.4
• /
• pp.234-241
• /
• 2000

The Saccharomyces cerevisiae PMR1 gene encodes a Ca2+-ATPase localized in the Golgi. We have investigated the effects of PMR1 disruption in S. cerevisiae on the glycosylation and secretion of three heterologous glycoproteins, human ${\alpha}$1-antitrypsin (${\alpha}$1-AT), human antithrombin III (ATHIII), and Aspergillus niger glucose oxidase (GOD). The pmr1 null mutant strain secreted larger amounts of ATHIII and GOD proteins per a unit cell mass than the wild type strain. Despite a lower growth rate of the pmr1 mutant, two-fold higher level of human ATHIII was detected in the culture supernatant from the pmr1 mutant compared to that of the wild-type strain. The pmr1 mutant strain secreted ${\alpha}$1-AT and the GOD proteins mostly as core-glycosylated forms, in contrast to the hyperglycosylated proteins secreted in the wild-type strain. Furthermore, the core-glycosylated forms secreted in the pmr1 mutant migrated slightly faster on SDS-PAGE than those secreted in the mnn9 deletion mutant and the wild type strains. Analysis of the recombinant GOD with anti-${\alpha}$1,3-mannose antibody revealed that GOD secreted in the pmr1 mutant did not have terminal ${\alpha}$1,3-linked mannose unlike those secreted in the mnn9 mutant and the wild type strains. The present results indicate that the pmr1 mutant, with the super-secretion phenotype, is useful as a host system to produce recombinant glycoproteins lacking high-mannose outer chains.

• Journal of Microbiology and Biotechnology
• /
• v.25 no.4
• /
• pp.526-536
• /
• 2015

Leptospirosis is a worldwide zoonotic disease caused by pathogenic Leptospira, a genus of which more than 250 serovars have been identified. Commercial bacterin vaccines are limited in that they lack both cross-protection against heterologous serovars and long-term protection. This study investigated in mice the immunogenicity of an anti-leptospirosis vaccine, using the outer membrane proteins LipL32 and Loa22 as antigens. The immunogenicity of this vaccine formulation was compared with those induced by vaccines based on LipL32 or Loa22 alone. A DNA-encapsulated chitosan nanoparticle was used for in vivo DNA delivery. Using a unique DNA plasmid expressing both lipL32 and loa22 for vaccination, higher antibody responses were induced than when combining plasmids harboring each gene separately. Therefore, this formulation was used to test the immunogenicity when administered by a heterologous prime (DNA)-boost (protein) immunization regimen. The specific antibody responses against LipL32 (total IgG and IgG1) and Loa22 (IgG1) were higher in mice receiving two antigens in combination than in those vaccinated with a single antigen alone. Although no significant difference in splenic CD4⁺ T cell proliferation was observed among all groups of vaccinated mice, splenocytes from mice vaccinated with two antigens exhibited higher interferon-γ and IL-2 production than when using single antigens alone upon in vitro restimulation. Taken together, the immunogenicity induced by LipL32 and Loa22 antigens in a heterologous primeboost immunization regimen using chitosan as a DNA delivery system induces higher immune response, and may be useful for developing a better vaccine for leptospirosis.

• Journal of Microbiology and Biotechnology
• /
• v.27 no.7
• /
• pp.1345-1358
• /
• 2017

The impact of overproduction of a heterologous protein on the metabolic system of host Lactococcus lactis was investigated. The protein expression profiles of L. lactis IL1403 containing two near-identical plasmids that expressed high- and low-level of the green fluorescent protein (GFP) were examined via shotgun proteomics. Analysis of the two strains via high-throughput LC-MS/MS proteomics identified the expression of 294 proteins. The relative amount of each protein in the proteome of both strains was determined by label-free quantification using the spectral counting method. Although expression level of most proteins were similar, several significant alterations in metabolic network were identified in the high GFP-producing strain. These changes include alterations in the pyruvate fermentation pathway, oxidative pentose phosphate pathway, and de novo synthesis pathway for pyrimidine RNA. Expression of enzymes for the synthesis of dTDP-rhamnose and N-acetylglucosamine from glucose was suppressed in the high GFP strain. In addition, enzymes involved in the amino acid synthesis or interconversion pathway were downregulated. The most noticeable changes in the high GFP-producing strain were a 3.4-fold increase in the expression of stress response and chaperone proteins and increase of caseinolytic peptidase family proteins. Characterization of these host expression changes witnessed during overexpression of GFP was might suggested the metabolic requirements and networks that may limit protein expression, and will aid in the future development of lactococcal hosts to produce more heterologous protein.

• Journal of Microbiology and Biotechnology
• /
• v.32 no.6
• /
• pp.749-760
• /
• 2022

α-Galactosidase is a debranching enzyme widely used in the food, feed, paper, and pharmaceuticals industries and plays an important role in hemicellulose degradation. Here, T26, an aerobic bacterial strain with thermostable α-galactosidase activity, was isolated from laboratory-preserved lignocellulolytic microbial consortium TMC7, and identified as Parageobacillus thermoglucosidasius. The α-galactosidase, called T26GAL and derived from the T26 culture supernatant, exhibited a maximum enzyme activity of 0.4976 IU/ml when cultured at 60℃ and 180 rpm for 2 days. Bioinformatics analysis revealed that the α-galactosidase T26GAL belongs to the GH36 family. Subsequently, the pET-26 vector was used for the heterologous expression of the T26 α-galactosidase gene in Escherichia coli BL21 (DE3). The optimum pH for α-galactosidase T26GAL was determined to be 8.0, while the optimum temperature was 60℃. In addition, T26GAL demonstrated a remarkable thermostability with more than 93% enzyme activity, even at a high temperature of 90℃. Furthermore, Ca²⁺ and Mg²⁺ promoted the activity of T26GAL while Zn²⁺ and Cu²⁺ inhibited it. The substrate specificity studies revealed that T26GAL efficiently degraded raffinose, stachyose, and guar gum, but not locust bean gum. This study thus facilitated the discovery of an effective heat-resistant α-galactosidase with potent industrial application. Meanwhile, as part of our research on lignocellulose degradation by a microbial consortium, the present work provides an important basis for encouraging further investigation into this enzyme complex.

• Microbiology and Biotechnology Letters
• /
• v.50 no.4
• /
• pp.501-507
• /
• 2022

PET (Polyethylene terephthalate), a representative plastic material, has useful physicochemical properties such as high durability and economic feasibility, and is used in various industrial fields such as bottles, fibers, and containers. Due to the recent increase in plastic usage including disposable products, eco-friendly strategy using microorganisms have drawn attention differentiated from conventional landfill and incineration methods. In this study, a soil-derived Streptomyces javensis Inha503 containing a PETase gene was selected and the ability to hydrolyze PU (Polyurethane) was confirmed through agar plate diffusion assay. This strain was cultured with PET for a month, and PET decomposition ability was also confirmed through a scanning electron microscope. Moreover, cloning and heterologous expression of S. javensis Inha503 PETase gene exhibited PET activity in the PETase non-containing S. coelicolor, confirming for the first time the presence of functional PETase gene in Streptomyces species.

• Journal of Microbiology and Biotechnology
• /
• v.33 no.3
• /
• pp.378-386
• /
• 2023

The CYP707A family genes encoding ABA 8'-hydroxylase catabolize abscisic acid (ABA), a plant stress hormone that plays an important role in stress condition, such as drought, heat, cold and salinity. Phaseic acid (PA) is a catabolic product of ABA. Recent studies have shown that PA is important for the physiological functions in plants. It is also a neuroprotective molecule that protects against ischemic brain injury in mice. To obtain enzymes for the PA production, four CaCYP707A genes (CaCYP707A1, CaCYP707A2, CaCYP707A3 and CaCYP707A4) were isolated from hot pepper. They were heterologously expressed in Escherichia coli. Among them, CaCYP707A2 showed significantly higher expression levels in both the membrane fraction and the soluble fraction. Preferred redox partners were investigated to improve the efficiency of CaCYP707A2's catalytic reaction, and NADPH-cytochrome P450 reductase (CPR) from hot pepper (CaCPR) was preferred over other redox partners (i.e., rat CPR and ferredoxin reductase/ferredoxin). The production of 8'-hydroxy ABA and PA by ABA hydroxylation activity was confirmed in CaCYP707A2 from both membrane and soluble fractions. Therefore, CaCYP707A2 is the first identified plant CYP protein that is expressed a soluble form in cytosolic fraction having stable activity. Taken together, we propose a new CYP707A protein with industrial applications for PA production without additional modifications in E. coli heterologous expression.

• IMMUNE NETWORK
• /
• v.5 no.2
• /
• pp.89-98
• /
• 2005

Background: DNA vaccination represents an anticipated approach for the control of numerous infectious diseases. Used alone, however, DNA vaccine is weak immunogen inferior to viral vectors. In recent, heterologous prime-boost vaccination leads DNA vaccines to practical reality. Methods: We assessed prime-boost immunization strategies with a DNA vaccine (minigene, $gB_{498-505}$ DNA) and recombinant vaccinia virus $(vvgB_{498-505})$ expressing epitope $gB_{498-505}$ (SSIEF ARL) of CD8+ T cells specific for glycoprotein B (gB) of herpes simplex virus (HSV). Animals were immunized primarily with $gB_{498-505}$ epitope-expressing DNA vaccine/recombinant vaccinia virus and boosted with alternative vaccine type expressing entire Ag. Results: In prime-boost protocols using vvgBw (recombinant vaccinia virus expressing entire Ag) and $vvgB_{498-505}$, CD8+ T cell-mediated immunity was induced maximally at both acute and memory stages if primed with vvgBw and boosted with $vvgB_{498-505}$ as evaluated by CTL activity, intracellular IFN-staining, and MHC class I tetramer staining. Similarly $gB_{498-505}$ DNA prime-gBw DNA (DNA vaccine expressing entire Ag) boost immunization elicited the strongest CD8+ T cell responses in protocols based on DNA vaccine. However, the level of CD8+ T cell-mediated immunity induced with prime-boost vaccination using DNA vaccine expressing epitope or entire Ag was inferior to those based on vvgBw and $vvgB_{498-505}$. Of particular interest CD8+ T cell-mediated immunity was optimally induced when $vvgB_{498-505}$ was used to prime and gB DNA was used as alternative boost. Especially CD7+ T cell responses induced by such protocol was longer lasted than other protocols. Conclusion: These facts direct to search for the effective strategy to induce optimal CD8+ T cell-mediated immunity against cancer and viral infection.

• Microbiology and Biotechnology Letters
• /
• v.47 no.4
• /
• pp.667-672
• /
• 2019

We compared two integration systems for stable expression of heterologous genes in Saccharomyces cerevisiae. A Candida glabrata-derived gene was used as the selective marker for the Cre/loxP system, and XYLP, XYLB, GRE3, and XYL2 genes were used as model heterologous genes and ligated into the universal pRS-CMT vector. The resulting pRS-XylP, pRS-XylB, pRS-Gre3, and pRS-Xyl2 plasmids were sequentially integrated into yeast chromosome VII by four integration processes (marker rescue and gene integration). The four introduced genes were successfully expressed. Further, the pRS-PBG2 plasmid harboring expression cassettes for the four genes was constructed for one-step integration. The four genes that were introduced were stably maintained as a gene cluster and were simultaneously expressed. The one-step integration was more effective for the simultaneous integration and expression of the four genes related to xylan/xylose metabolism. This method will enable the generation of a useful biosystem through appropriate use of gene integration methods.