Journal of Microbiology

Journal Articles

Infection Dynamics of Dengue Virus in Caco-2 Cells Depending on Its Differentiation Status.: Jayoung Nam, Jisu Lee, Geon A Kim, Seung-Min Yoo, Changhoon Park, Myung-Shin Lee; J. Microbiol. 2024;62(9):799-809. Published online August 30, 2024; DOI: https://doi.org/10.1007/s12275-024-00161-w

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Abstract: Dengue virus (DENV), from the Flaviviridae family, is the causative agent of dengue fever and poses a significant global health challenge. The virus primarily affects the vascular system and liver; however, a growing body of evidence suggests its involvement in the gastrointestinal (GI) tract, contributing to clinical symptoms such as abdominal pain, vomiting, and diarrhea. However, the mechanisms underlying DENV infection in the digestive system remain largely unexplored. Prior research has detected viral RNA in the GI tissue of infected animals; however, whether the dengue virus can directly infect human enterocytes remains unclear. In this study, we examine the infectivity of human intestinal cell lines to the dengue virus and their subsequent response. We report that the Caco-2 cell line, a model of human enterocytes, is susceptible to infection and capable of producing viruses. Notably, differentiated Caco-2 cells exhibited a lower infection rate yet a higher level of virus production than their undifferentiated counterparts. These findings suggest that human intestinal cells are a viable target for the dengue virus, potentially elucidating the GI symptoms observed in dengue fever and offering a new perspective on the pathogenetic mechanisms of the virus.

Yeast polyubiquitin unit regulates synaptonemal complex formation and recombination during meiosis: Min-Kyung Jo , Kiwon Rhee , Keun Pil Kim , Soogil Hong; J. Microbiol. 2022;60(7):705-714. Published online July 4, 2022; DOI: https://doi.org/10.1007/s12275-022-2204-y

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Abstract: Ubiquitin is highly conserved in most eukaryotes and involved in diverse physiological processes, including cell division, protein quality control, and protein degradation mediated by the ubiquitin-proteasome system after heat shock, glucose-starvation, and oxidative stress. However, the role of the ubiquitin gene UBI4, which contains five consecutive head-to-tail ubiquitin repeats, in meiosis has not been investigated. In this study, we show that the Saccharomyces cerevisiae polyubiquitin precursor gene, UBI4, is required to promote synaptonemal complex (SC) formation and suppress excess doublestrand break formation. Moreover, the proportion of Zip1 polycomplexes, which indicate abnormal SC formation, in cells with a mutation in UBI4 (i.e., ubi4Δ cells) is higher than that of wild-type cells, implying that the UBI4 plays an important role in the early meiotic prophase I. Interestingly, although ubi4Δ cells rarely form full-length SCs in the pachytene stage of prophase I, the Zip3 foci are still seen, as in wild-type cells. Moreover, ubi4Δ cells proficiently form crossover and noncrossover products with a slight delay compared to wild-type cells, suggesting that UBI4 is dispensable in SCcoupled recombination. Our findings demonstrate that UBI4 exhibits dual functions that are associated with both positive and negative roles in SC formation and recombination during meiosis.

Activity of Lactobacillus crispatus isolated from vaginal microbiota against Mycobacterium tuberculosis: Youngkyoung Lee , Hoonhee Seo , Sukyung Kim Abdur Rahim , Youjin Yoon , Jehee Jung , Saebim Lee , Chang Beom Ryu , Ho-Yeon Song; J. Microbiol. 2021;59(11):1019-1030. Published online November 1, 2021; DOI: https://doi.org/10.1007/s12275-021-1332-0

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9 Citations

Abstract: Tuberculosis, an infectious disease, is caused by Mycobacterium tuberculosis. It remains a significant public health issue around the globe, causing about 1.8 million deaths every year. Drug-resistant M. tuberculosis, including multi-drug-resistant (MDR), extremely-drug-resistant (XDR), and totally drugresistant (TDR) M. tuberculosis, continues to be a threat to public health. In the case of antibiotic-resistant tuberculosis, the treatment effect of conventional antibiotics is low. Side effects caused by high doses over a long period are causing severe problems. To overcome these problems, there is an urgent need to develop a new anti-tuberculosis drug that is different from the existing compound-based antibiotics. Probiotics are defined as live microorganisms conferring health benefits. They can be potential therapeutic agents in this context as the effectiveness of probiotics against different infectious diseases has been well established. Here, we report that Lactobacillus crispatus PMC201 shows a promising effect on tuberculosis isolated from vaginal fluids of healthy Korean women. Lactobacillus crispatus PMC201 reduced M. tuberculosis H37Rv under co-culture conditions in broth and reduced M. tuberculosis H37Rv and XDR M. tuberculosis in macrophages. Lactobacillus crispatus PMC201 was not toxic to a guinea pig model and did not induce dysbiosis in a human intestinal microbial ecosystem simulator. Taken together, these
results
indicate that L. crispatus PMC201 can be a promising alternative drug candidate in the current tuberculosis drug regime. Further study is warranted to assess the in vivo efficacy and confirm the mode of action of L. crispatus PMC201.

Crystal structure of human LC8 bound to a peptide from Ebola virus VP35: Dahwan Lim , Ho-Chul Shin , Joon Sig Choi , Seung Jun Kim , Bonsu Ku; J. Microbiol. 2021;59(4):410-416. Published online February 25, 2021; DOI: https://doi.org/10.1007/s12275-021-0641-7

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4 Citations

Abstract: Zaire ebolavirus, commonly called Ebola virus (EBOV), is an RNA virus that causes severe hemorrhagic fever with high mortality. Viral protein 35 (VP35) is a virulence factor encoded in the EBOV genome. VP35 inhibits host innate immune responses and functions as a critical cofactor for viral RNA replication. EBOV VP35 contains a short conserved motif that interacts with dynein light chain 8 (LC8), which serves as a regulatory hub protein by associating with various LC8-binding proteins. Herein, we present the crystal structure of human LC8 bound to the peptide comprising residues 67−76 of EBOV VP35. Two VP35 peptides were found to interact with homodimeric LC8 by extending the central β- sheets, constituting a 2:2 complex. Structural analysis demonstrated that the intermolecular binding between LC8 and VP35 is mainly sustained by a network of hydrogen bonds and supported by hydrophobic interactions in which Thr73 and Thr75 of VP35 are involved. These findings were verified by binding measurements using isothermal titration calorimetry. Biochemical analyses also verified that residues 67−76 of EBOV VP35 constitute a core region for interaction with LC8. In addition, corresponding motifs from other members of the genus Ebolavirus commonly bound to LC8 but with different binding affinities. Particularly, VP35 peptides originating from pathogenic species interacted with LC8 with higher affinity than those from noninfectious species, suggesting that the binding of VP35 to LC8 is associated with the pathogenicity of the Ebolavirus species.

Review

[MINIREVIEW]Phosphate sugar isomerases and their potential for rare sugar bioconversion: Soo-Jung Kim , Yeong-Su Kim , Soo-Jin Yeom; J. Microbiol. 2020;58(9):725-733. Published online June 25, 2020; DOI: https://doi.org/10.1007/s12275-020-0226-x

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6 Citations

Abstract: Phosphate sugar isomerases, catalyzing the isomerization between ketopentose/ketohexose phosphate and aldopentose/ aldohexose phosphate, play an important role in microbial sugar metabolism. They are present in a wide range of microorganisms. They have attracted increasing research interest because of their broad substrate specificity and great potential in the enzymatic production of various rare sugars. Here, the enzymatic properties of various phosphate sugar isomerases are reviewed in terms of their substrate specificities and their applications in the production of valuable rare sugars because of their functions such as low-calorie sweeteners, bulking agents, and pharmaceutical precursor. Specifically, we focused on the industrial applications of D-ribose-5-phosphate isomerase and D-mannose-6-phosphate isomerase to produce D-allose and L-ribose, respectively.

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