Jun Hyeong Jang

Alteration of Histone H3 Lysine 4 Trimethylation on Putative Lytic Gene Promoters by Human Set1 Complex during Reactivation of Kaposi’s Sarcoma-Associated Herpesvirus

Objective: Histone H3 lysine 4 is trimethylated by the human Set1 complex, which regulates the activation of gene expression. The aim of this study was to identify whether the levels of histone H3 lysine 4 trimethylation (H3K4me3) and the recruitment of human Set1 complex at the promoter regions of lytic genes quantitatively change during reactivation from latent to lytic infection of Kaposi’s sarcoma-association herpesvirus (KSHV). Methods: During KSHV reactivation, global changes of H3K4 methylation in KSHV-infected cells were analyzed by Western blot. The relative levels of association between proteins and promoter regions were determined by chromatin immunoprecipitation assay and quantitative real-time PCR using specific antibodies and primer sets. Results: Our results showed that KSHV reactivation does not alter the overall cellular levels of H3K4 methylation. We observed that the switch from latency to lytic cycle leads to upregulation of H3K4me3 at the active lytic genes. We also found that the recruitment of RNA pol II and subunits of human Set1 complex were enriched at the same regions in response to KSHV reactivation. Conclusion: These results demonstrate that the increase of H3K4me3 by human Set1 complex is involved in activation of lytic genes during the lytic infection of KSHV.

Metagenomic Analysis of Airborne Bacterial Community and Diversity in Seoul, Korea, during December 2014, Asian Dust Event.

Asian dust or yellow sand events in East Asia are a major issue of environmental contamination and human health, causing increasing concern. A high amount of dust particles, especially called as particulate matter 10 (PM10), is transported by the wind from the arid and semi-arid tracks to the Korean peninsula, bringing a bacterial population that alters the terrestrial and atmospheric microbial communities. In this study, we aimed to explore the bacterial populations of Asian dust samples collected during November–December 2014. The dust samples were collected using the impinger method, and the hypervariable regions of the 16S rRNA gene were amplified using PCR followed by pyrosequencing. Analysis of the sequencing data were performed using Mothur software. The data showed that the number of operational taxonomic units and diversity index during Asian dust events were higher than those during non-Asian dust events. At the phylum level, the proportions of Proteobacteria, Actinobacteria, and Firmicutes were different between Asian dust and non-Asian dust samples. At the genus level, the proportions of the genus Bacillus (6.9%), Arthrobacter (3.6%), Blastocatella (2%), Planomicrobium (1.4%) were increased during Asian dust compared to those in non-Asian dust samples. This study showed that the significant relationship between bacterial populations of Asian dust samples and non-Asian dust samples in Korea, which could significantly affect the microbial population in the environment.

Alterations in the airborne bacterial community during Asian dust events occurring between February and March 2015 in South Korea.

During Asian dust events, a relatively high concentration of particulate matter is transported by wind from arid and semi-arid regions, such as the Gobi and Taklamakan deserts, to nearby countries, including China, Korea, and Japan. The dust particles contain various microorganisms, which can affect human health as well as the environmental microbe population. In the current study, we investigated the characteristics of the airborne bacterial community during Asian dust events between February and March 2015 in South Korea. Bacterial diversity indexes such as operational taxonomic units, Chao1 and Inverse Simpson index were increased, along with total 16S rRNA gene copy number during Asian dust events. The bacterial community structure during Asian dust events was clearly distinguishable from that during non-Asian dust days. The genera Bacillus and Modestobacter were increased 3.9- and 2.7-fold, respectively, while Escherichia-Shigella was decreased by 89.8%. A non-metric multidimensional scaling plot with metadata analysis revealed association of particulate matter concentration, but not temperature, humidity or wind speed, with bacterial community structure, suggesting that the newly transported dust particles contain various microorganisms that influence the airborne bacterial environment.

Lysobacter humi sp. nov., isolated from soil

A yellow-pigmented and strictly aerobic bacterial strain, designated FJY8T, was isolated from the soil of Goyang, South Korea. The cells of FJY8T were Gram-reaction-negative, non-motile rods. Colonies were circular, convex and transparent. Strain FJY8T grew optimally at 30 °C, with 0 % (w/v) NaCl and at pH 8. Phylogenetic analysis of the 16S rRNA gene sequence of FJY8T revealed a clear affiliation of this bacterium to the family Lysobacteraceae, and it was related to members of the genus Lysobacter, with Lysobacter xinjiangensis KCTC 22558T being its closest relative (98.7 % sequence similarity). The DNA G+C content was 68.0±0.4 mol%. Diphosphatidylglycerol, phosphatidylethanolamine and phosphatidylglycerol were identified as the major polar lipids, and an unidentified phospholipid and two unidentified aminophospholipids were also detected as the minor polar lipids. The major fatty acids were iso-C16 : 0, summed feature 9 (iso-C17 : 1ω9c and/or C16 : 0 10-methyl) and iso-C15 : 0. Only ubiquinone-8 (Q-8) was detected as the isoprenoid quinone. DNA-DNA hybridization values of strain FJY8T with Lysobacter xinjiangensisRCML-52T and Lysobacter mobilis9NM-14T were 55.8±2.0 and 45.2±4.8 %, respectively. On the basis of DNA-DNA hybridization, phylogenetic distinctiveness, and some physiological and biochemical tests, strain FJY8T (=KCTC 42810T=JCM 31019T) represents a novel species of the genus Lysobacter, for which the name Lysobacter humi sp. nov. is proposed.

Lysobacter pedocola sp. nov., a novel species isolated from Korean soil

A Gram-negative, yellow-pigmented bacterial strain, designated IPC6T, was isolated from soil in an arid region of Goyang-si (Gyeonggi-do, South Korea). Cells were strictly aerobic, non-spore-forming, rod-shaped. The strain grew within a temperature range of 10–42°C (optimum, 30°C) and pH of 5.0–11.0 (optimum, pH 8.0) in the presence of 0–2% (w/v) NaCl. Phylogenetically, the novel strain was closely related to members of the Lysobacter genus based on 16S rRNA sequence similarity, and showed the highest sequence similarity to Lysobacter niastensis KACC 11588T (98.5%). The predominant fatty acids were iso-C15:0, iso-C16:0, and summed feature 9 (iso-C17:1ω9c), with Q-8 identified as the major ubiquinone. The polar lipid content included diphosphatidylglycerol, phosphatidylethanolamine, phosphatidylglycerol, an unknown aminophospholipid, and an unidentified phospholipid. DNA-DNA hybridization results indicated that the strain IPC6T was distinct from Lysobacter niastensis KACC 11588T (37.9 ± 0.14%), Lysobacter panacisoli KACC 17502T (56.4 ± 0.13%), Lysobacter soli KCTC 22011T (8.1 ± 0.04%), Lysobacter gummosus KCTC 12132T (9.6 ± 0.03%), and Lysobacter cavernae KCTC 42875T (37.5 ± 0.14%), respectively. The DNA G + C content of the novel strain was 71.1 mol%. Based on the collective phenotypic, genotypic and chemotaxonomic data, the IPC6T strain is considered to represent a novel species in the genus Lysobacter, for which the name Lysobacter pedocola sp. nov. (= KCTC 42811T = JCM 31020T) is proposed.

Aestuariibaculum marinum sp. nov., a marine bacterium isolated from seawater in South Korea

A Gram-negative, non-motile, aerobic bacterium, designated strain IP7T, was isolated from seawater at the shore of the Incheon Eulwang-ri beach, South Korea. Cells of strain IP7T are straight or slightly rod-shaped and colonies are round, convex and orange-yellow. Strain IP7T is flexirubin-negative, mild halophile, catalase-and oxidase-positive, and produces a yellow-orange carotenoid pigment. Growth is optimal at 30°C, pH 7–9, and 2.0–4.0% NaCl (w/v). On the basis of 16S rRNA gene sequence similarity, strain IP7T is affiliated with genus Aestuariibaculum in the family Flavobacteriaceae, the closest relative being Aestuariibaculum suncheonense SC17T (98.3% sequence similarity). The DNA G + C content of the novel strain is 37.4 mol%. The only quinone is MK-6 menaquinone. Iso-branched C15:0, iso-branched C15:1 G, and iso-branched C17:0 3-OH are major fatty acids. The major polar lipids are phosphatidylethanolamine, an unidentified aminoglycolipid and two unidentified glycolipids. The DNA-DNA hybridization value of strain IP7T with Aestuariibaculum suncheonense SC17T is 28.87%. Based on the collective DNA-DNA hybridization, biochemical, phylogenetic and physiological data, we report a novel species of the genus Aestuariibaculum for which the name Aestuariibaculum marinum sp. nov. is proposed. The type strain is IP7T (= KCTC 52521T = JCM 31725T).

Alterations in Acetylation of Histone H4 Lysine 8 and Trimethylation of Lysine 20 associated with Lytic Gene Promoters during Kaposi's Sarcoma-Associated Herpesvirus Reactivation.

Kaposis sarcoma-associated herpesvirus (KSHV) is associated with formation of Kaposis sarcoma, multicentric Castlemans disease, and primary effusion lymphoma. Replication and transcription activator (RTA) genes are expressed upon reactivation of KSHV, which displays a biphasic life cycle consisting of latent and lytic replication phases. RTA protein expression results in KSHV genome amplification and successive viral lytic gene expression. Transcriptional activity of viral lytic genes is regulated through epigenetic modifications. In Raji cells latently infected with Epstein-Barr virus, various modifications, such as acetylation and methylation, have been identified at specific lysine residues in histone H4 during viral reactivation, supporting the theory that expression of specific lytic genes is controlled by histone modification processes. Data obtained from chromatin immunoprecipitation and quantitative real-time PCR analyses revealed alterations in the H4K8ac and H4K20me3 levels at lytic gene promoters during reactivation. Our results indicate that H4K20me3 is associated with the maintenance of latency, while H4K8ac contributes to KSHV reactivation in infected TREx BCBL-1 RTA cells.

Ensifer collicola sp. nov., a bacterium isolated from soil in South Korea

Strain Mol12T, which presented in the form of Gram-negative, motile, non-spore forming rod-shaped, was isolated from soil in South Korea and characterized to determine its taxonomic position. The strain grew at 20–30°C (optimum 30°C) and pH 7.0–10.0 (optimum pH 8.0) with 1% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain Mol12T was most closely related to Ensifer terangae LMG 7834T (96.78%), Rhizobium daejeonense KCTC 12121T (96.43%), Ensifer adhaerens Casida AT (96.28%). Chemotaxonomic data showed that the predominant fatty acids were Summed Feature 8 (C18:1ω7c and/or C18:1ω6c; 53.02%) and C18:1ω7c 11-methyl (24.01%). Its complex polar lipid contained major amounts of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE) and Q-10 as the predominant ubiquinone. The DNA G+C content of strain Mol12T was determined to be 60.9 mol%. Based on the phylogenetic, chemotaxonomic, and phenotypic data, strain Mol12T (=KCTC 42816T =JCM 31049T) ought to be classified as a type strain of a novel species, for which the name Ensifer collicola sp. nov. is proposed.

Analysis of Kaposi's sarcoma-associated herpesvirus latent replication using a real-time polymerase chain reaction technique

Kaposis sarcoma-associated herpesvirus (KSHV) undergoes replication independently via latent and lytic pathways. Latent replication is mediated by latent-associated nuclear antigen (LANA), the sole viral trans element for genome maintenance and replication. According to previous studies, LANA tethers the KSHV genome to the host chromosome during latency and interacts with host factors to ensure proper latent replication. Studies using Southern blot experiments have revealed consistently that vector constructs containing the viral terminal repeat (TR) region as a cis element in latent replication are replicated in the presence of LANA. However, Southern blotting is a time-intensive, complicated technique that requires multiple reagents. In addition, it has a limited ability to detect slight changes in replication efficiency under different conditions owing to its relatively low sensitivity. In the current study, a real-time polymerase chain reaction method was developed for detecting transient KSHV replication and was found to be capable of further identifying several factors that affect latent replication. This technique should provide a useful tool for the detection of KSHV latent replication under various conditions, including overexpression of viral or cellular factors and chemical stimulation.