• Journal of Microbiology and Biotechnology
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• v.31 no.1
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• pp.16-24
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• 2021

Hepatitis B virus (HBV) genome P-encoded protein HBV DNA polymerase (Pol) has long been known as a reverse transcriptase during HBV replication. In this study, we investigated the impact of HBV Pol on host cellular processes, mainly apoptosis, and the underlying mechanisms. We showed a marked reduction in apoptotic rates in the HBV Pol-expressed HepG2 cells compared to controls. Moreover, a series of assays, i.e., yeast two-hybrid, GST pull-down, co-immunoprecipitation, and confocal laser scanning microscopy, identified the host factor eEF1A2 to be associated with HBV Pol. Furthermore, knockdown of eEF1A2 gene by siRNA abrogated the HBV Pol-mediated anti-apoptotic effect with apoptosis induced by endoplasmatic reticulum (ER) stress-inducer thapsigargin (TG), thus suggesting that the host factor eEF1A2 is essential for HBV Pol's anti-apoptosis properties. Our findings have revealed a novel role for HBV Pol in its modulation of apoptosis through integrating with eEF1A2.

• Molecules and Cells
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• v.45 no.8
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• pp.522-530
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• 2022

Transposable elements (TEs) account for approximately 45% of the human genome. TEs have proliferated randomly and integrated into functional genes during hominoid radiation. They appear as right-handed B-DNA double helices and slightly elongated left-handed Z-DNAs. Human endogenous retrovirus (HERV) families are widely distributed in human chromosomes at a ratio of 8%. They contain a 5'-long terminal repeat (LTR)-gag-pol-env-3'-LTR structure. LTRs contain the U3 enhancer and promoter region, transcribed R region, and U5 region. LTRs can influence host gene expression by acting as regulatory elements. In this review, we describe the alternative promoters derived from LTR elements that overlap Z-DNA by comparing Z-hunt and DeepZ data for human functional genes. We also present evidence showing the regulatory activity of LTR elements containing Z-DNA in GSDML. Taken together, the regulatory activity of LTR elements with Z-DNA allows us to understand gene function in relation to various human diseases.

• BMB Reports
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• v.41 no.8
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• pp.587-592
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• 2008

Cotesia vestalis is an endoparasitoid of Plutella xylostella larvae and injects a polydnavirus (CvBV) into its host during oviposition. In this report we characterize the gene, CvBV3307, and its products. CvBV3307 is located on segment S33 of the CvBV genome, is 517 bp, and encodes a putative protein of 122 amino acids, including a serine-rich region. The expression pattern of CvBV3307 in parasitized larvae and the subcellular localization of CvBV3307 only in granulocytes indicated that it might be involved in early protection of parasitoid eggs from host cellular encapsulation and in manipulating the hormone titer and developmental rhythm of host larvae. Western blot analysis showed that the size of the immunoreactive protein (about 55 kDa) in parasitized hosts at 48 hours post parasitization (h p.p.) is much larger than the predicted molecular weight of 13.6 kDa, which suggests that CvBV3307 undergoes extensive post-translational modification in hosts.

• Asian-Australasian Journal of Animal Sciences
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• v.21 no.11
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• pp.1572-1575
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• 2008

The xenotransplantation of pig organs and cells can be related with a risk of transmission of infectious diseases to human. Previous findings indicate that the regulatory region of PERV for retroviral transcription, replication and integration into the cellular DNA is located on the 5' Long Terminal Repeat (LTR). The objective of this study is the investigation of methylation and deletion status of the PERV 5' LTR region which can be used for regulating PERV expression. We compared the sequences of genomic DNA and bisulfite-treated genomic DNA from PK-15 cells expressing PERV to observe the methylation status of the 5' LTR. Our results showed that the CpG sites of U3 were methylated and methylation was inconsistent in the R and U5 regions. Also, variable numbers of 18 bp repeats and 21 bp repeats were detected on 5' LTR by sequencing analysis. The consistent U3 methylation might be indicative of host suppression of expression of the retroviruses.

• Proceedings of the Korean Society of Plant Pathology Conference
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• 2003.10a
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• pp.84.1-84
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• 2003

Magnaporthe grisea, the casual agent of rice blast, forms an appressorium to penetrate its host. Much has been learned about environmental cues and signal transduction pathways, especially those involving CAMP and MAP kinases, on appressorium formation during the last decade. More recently, pharmacological data suggest that calcium/calmodulin-dependent signaling system is involved in its appressorium formation. To determine the role of phosphoinositide-specific phospholipase C (PI-PLC) on appressorium formation, a gene (WPLCl) encoding PI-PLC was cloned and characterized from M. grisea strain 70-15. Sequence analysis showed that MPLCl has alt five conserved domains present in other phospholipase C genes from several filamentous fungi and mammals. Null mutants (mplcl) generated by targeted gene disruption exhibited pleiotropic effects on conidial morphology, appressorium formation, fertility and pathogenicity. mplcl mutants developed nonfunctional appressoria and are also defective in infectious growth in host tissues. Defects in appressorium formation and pathogenicity in mplcl mutants were complemented by a mouse PLCdelta-1 cDNA under the control of the MPLCl promoter. These results suggest that cellular signaling mediated by MPLCl plays crucial and diverse roles in development and pathogenicity of M. grisea, and functional conservation between fungal and mammalian Pl-PLCs.

• Molecules and Cells
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• v.21 no.1
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• pp.21-28
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• 2006

The interferon-induced, double-stranded RNA (dsRNA)-dependent protein kinase PKR plays a key role in interferon-mediated host defense against viral infection, and is implicated in cellular transformation and apoptosis. We have isolated a cDNA of simian PKR encoding a product with 83% amino acid identity to the human homolog and showed that PKR expression is significantly attenuated in the Vero E6 African green monkey kidney cells devoid of type I interferon genes. A variant form of PKR lacking the exon 12 in the kinase domain is produced in these cells, presumably from an alternatively spliced transcript. Unlike wild type PKR, the variant protein named PKR-${\Delta}E12$ is incapable of auto-phosphorylation and phosphorylation of eIF2-${\alpha}$, indicating that the kinase sub-domains III and IV embedded in exon 12 are indispensable for catalytic function. PKR-${\Delta}E12$ had no dominant negative effect but was weakly phosphorylated in trans by wild type PKR.

• Molecules and Cells
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• v.44 no.5
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• pp.342-355
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• 2021

The microphthalmia-associated transcription factor family (MiT family) proteins are evolutionarily conserved transcription factors that perform many essential biological functions. In mammals, the MiT family consists of MITF (microphthalmia-associated transcription factor or melanocyte-inducing transcription factor), TFEB (transcription factor EB), TFE3 (transcription factor E3), and TFEC (transcription factor EC). These transcriptional factors belong to the basic helix-loop-helix-leucine zipper (bHLH-LZ) transcription factor family and bind the E-box DNA motifs in the promoter regions of target genes to enhance transcription. The best studied functions of MiT proteins include lysosome biogenesis and autophagy induction. In addition, they modulate cellular metabolism, mitochondria dynamics, and various stress responses. The control of nuclear localization via phosphorylation and dephosphorylation serves as the primary regulatory mechanism for MiT family proteins, and several kinases and phosphatases have been identified to directly determine the transcriptional activities of MiT proteins. In different immune cell types, each MiT family member is shown to play distinct or redundant roles and we expect that there is far more to learn about their functions and regulatory mechanisms in host defense and inflammatory responses.

• Microbiology and Biotechnology Letters
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• v.22 no.5
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• pp.467-476
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• 1994

Lactobacillus casei HY 2782, prophage cured strain was characterized to be stable as much as L casei YIT 9018, parent strain. By southern hybridization, it was confirmed that the temperate phage was incorporated in chromosomal DNA of L. casei YIT 9018 as a prophage. It was also proved that the prophage was cured from chromosomal DNA of L casei HY 2782. The growth rate, lactic acid producing ability, carbohydrates fermentation, and enzymatic activity of L. casei HY 2782 were found to be similar to those of L. casei YIT 9018. When L casei HY 2782 was used as a host, the multiplicity of infection (M.O.I.) of the temperate phage for L. casei HY 2782 was 1.0~5.0. Restriction enzyme analysis of pLC90 plasmid from L. casei HY 2782 was shown that the size was an approximately 68.22 kb. The plasmid profiles, genomic DNA patterns, and cellular fatty acids composition of L. casei HY 2782 were similar to those of L casei YIT 9018. And the major fatty acids composition of these strains were C$_{14;0}$,C$_{16;1}$, C$_{16;0}$, C$_{18;1}$ and C$_{19;cyclo-}$ 10 sets of arbitrary primer in the PCR were screened to find differentiation against two strains of L. casei. Among them, b$_{5}-1/17-1 primer was produced an approximately 1.3 kb DNA band of only L casei YIT 9018. And b$_{5}-2/17-2 primer was produced an approximately 1.0 kb DNA band of only L casei HY 2782.

• Molecules and Cells
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• v.25 no.4
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• pp.510-522
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• 2008

To construct the molecular systematics of the genus Megoura (Hemiptera: Aphididae), DNA based-identification was performed using four mitochondrial and three nuclear DNA regions: partial cytochrome c oxidase I (COI), partial tRNA-leucine + cytochrome c oxidase II (tRNA/COII), cytochrome b (CytB), partial 12S rRNA + tRNA-valine + 16S rRNA (12S/16S), elongation factor-1 alpha ($EF1{\alpha}$), and the internal transcribed spacers 1 and 2 (ITS1, ITS2). Pairwise sequence divergences between taxa were compared, and phylogenetic analyses were performed based on each DNA region separately, and the combined datasets. COI, CytB, $EF1{\alpha}$, ITS1, and ITS2 were relatively effective in determining species and resolving their relationships. By contrast, the sequences of tRNA/COII and 12S/16S were not able to separate the closely related species. CytB and $EF1{\alpha}$ gave better resolution with higher average sequence divergences (4.7% for CytB, 5.2% for $EF1{\alpha}$). The sequence divergence of COI (3.0%) was moderate, and those of the two ITS regions (1.8% for ITS1, 2.0% for ITS2) were very low. Phylogenetic trees were constructed by minimum evolution, maximum parsimony, maximum likelihood, and Bayesian phylogenetic analyses. The results indicated that the phylogenetic relationships between Megoura species were associated with their host preferences. Megoura brevipilosa and M. lespedezae living on Lespedeza were closely related, and M. nigra, monophagous on Vicia venosa, was rather different from M. crassicauda, M. litoralis, and M. viciae, which are oligophagous on Lathyrus and Vicia. The three populations of M. crassicauda formed a clade separated from M. litoralis and M. viciae. Nevertheless M. litoralis and M. viciae, which are morphologically similar, were not separated due to negligible sequence divergence. We discuss the phylogenetic relationships of the Megoura, and the usefulness of the seven DNA regions for determining the species level phylogeny of aphids.

• Journal of Microbiology and Biotechnology
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• v.4 no.3
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• pp.176-182
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• 1994

The light-organ symbiont of pine cone fish, Vibrio fischeri, senses its presence in the host and responds to environmental changes by differentially expressing its symbiosis-related luminescence genes. The V. fischeri luminescence genes are activated by LuxR protein in the presence of an autoinducer. In an effort to elucidate the mechanism of regulation of luxR, a plasmid containing luxR was mutagenized in vitro with hydroxylamine and a luxR mutant plasmid was isolated by its ability to activate luminescence genes cloned in E. coli in the absence of the autoinducer. The specific base change identified by DNA sequencing was only single base transition at ＋78 from the transcriptional start of luxR. Based on a Western immunoblot analysis, the nucleotide change directed the synthesis of much higher level of LuxR protein without any amino acid substitutions. The results suggest that the region including the ＋78th base is presumably internal operator required for autorepression of luxR, and the increased cellular level of LuxR results in activation of luminescence genes by autoinducer independent fashion.