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Trans-acting regulators of ribonuclease activity
Lee Jaejin,이민호,Lee Kangseok 한국미생물학회 2021 The journal of microbiology Vol.59 No.4
RNA metabolism needs to be tightly regulated in response to changes in cellular physiology. Ribonucleases (RNases) play an essential role in almost all aspects of RNA metabolism, including processing, degradation, and recycling of RNA molecules. Thus, living systems have evolved to regulate RNase activity at multiple levels, including transcription, post-transcription, post-translation, and cellular localization. In addition, various trans-acting regulators of RNase activity have been discovered in recent years. This review focuses on the physiological roles and underlying mechanisms of trans-acting regulators of RNase activity.
Effect of Monomers in Vinyl Urethane Macromonomers on Dispersion Polymerization of Polystyrene
( Kangseok Lee ),( Sang Eun Shim ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.2
The four different vinyl monomers in the reaction of isocyanate-terminated polyurethane prepolymer were used for the preparation of macromonomers and successfully employed in the dispersion polymerization of styrene. The chemical structures of vinyl monomer in macromonomers influenced on the polystyrene particle characteristics, such as the conversion, weight average molecular weights (Mw), polydispersity index (PDI), weight average diameter (Dw), and uniformity. The conversion of polystyrene increased with amounts of methyl group in vinyl monomer. Also the uniformity of polystyrene particles increased with amounts of methyl group in vinyl monomer.
Synthesis of Alkoxy Modified Silicone Using Alkali Catalyst
( Kangseok Lee ),( Sang Eun Shim ) 한국고무학회 2016 엘라스토머 및 콤포지트 Vol.51 No.2
Alkoxy modified silicone (PAMS) was synthesized from hydroxyl-terminated polydimethylsiloxane (OHPDMS) and vinyltrimethoxysilane (VTMO) under alkali catalyst (NaOH and KOH) at room temperature (25℃) via condensation polymerization. Then, the structural verification of the synthesized PAMS was confirmed using 1H-NMR and FTIR spectroscopy. The reaction rate of PAMSs was studied in terms of the concentration variation of alkali catalyst. The reaction rate increased with the concentration of alkali catalyst, but no correlation between conversion and concentration of alkali catalyst was observed.
Regulator of ribonuclease activity modulates the pathogenicity of Vibrio vulnificus
Lee Jaejin,Shin Eunkyoung,Park Jaeyeong,이민호,Lee Kangseok 한국미생물학회 2021 The journal of microbiology Vol.59 No.12
RraA, a protein regulator of RNase E activity, plays a unique role in modulating the mRNA abundance in Escherichia coli. The marine pathogenic bacterium Vibrio vulnificus also possesses homologs of RNase E (VvRNase E) and RraA (VvRraA1 and VvRraA2). However, their physiological roles have not yet been investigated. In this study, we demonstrated that VvRraA1 expression levels affect the pathogenicity of V. vulnificus. Compared to the wild-type strain, the VvrraA1-deleted strain (ΔVvrraA1) showed decreased motility, invasiveness, biofilm formation ability as well as virulence in mice; these phenotypic changes of ΔVvrraA1 were restored by the exogenous expression of VvrraA1. Transcriptomic analysis indicated that VvRraA1 expression levels affect the abundance of a large number of mRNA species. Among them, the halflives of mRNA species encoding virulence factors (e.g., smcR and htpG) that have been previously shown to affect VvrraA1 expression-dependent phenotypes were positively correlated with VvrraA1 expression levels. These findings suggest that VvRraA1 modulates the pathogenicity of V. vulnificus by regulating the abundance of a subset of mRNA species.
Development of DNA aptamers specific for small therapeutic peptides using a modified SELEX method
Lee Jaemin,Ryu Minkyung,Bae Dayeong,Kim Hong-Man,Eyun Seong-il,Bae Jeehyeon,Lee Kangseok 한국미생물학회 2022 The journal of microbiology Vol.60 No.7
Aptamers are short single-stranded DNA or RNA oligonucleotides capable of binding with high affinity and specificity to target molecules. Because of their durability and ease of synthesis, aptamers are used in a wide range of biomedical fields, including the diagnosis of diseases and targeted delivery of therapeutic agents. The aptamers were selected using a process called systematic evolution of ligands by exponential enrichment (SELEX), which has been improved for various research purposes since its development in 1990. In this protocol, we describe a modified SELEX method that rapidly produces high aptamer screening yields using two types of magnetic beads. Using this method, we isolated an aptamer that specifically binds to an antimicrobial peptide. We suggest that by conjugating a small therapeutic-specific aptamer to a gold nanoparticle-based delivery system, which enhances the stability and intracellular delivery of peptides, aptamers selected by our method can be used for the development of therapeutic agents utilizing small therapeutic peptides.
Lee, Seunghwa,Yeom, Ji-Hyun,Seo, Sojin,Lee, Minho,Kim, Sarang,Bae, Jeehyeon,Lee, Kangseok,Hwang, Jihwan Microbiological Society of Korea 2015 The journal of microbiology Vol.53 No.4
<P>Resistance-nodulation-division (RND) efflux pumps are associated with multidrug resistance in many gram-negative pathogens. The genome of Vibrio vulnificus encodes 11 putative RND pumps homologous to those of Vibrio cholerae and Escherichia coli. In this study, we analyzed three putative RND efflux pumps, showing homology to V. cholerae VexAB and VexCD and to E. coli AcrAB, for their functional roles in multidrug resistance of V. vulnificus. Deletion of the vexAB homolog resulted in increased susceptibility of V. vulnificus to bile acid, acriflavine, ethidium bromide, and erythromycin, whereas deletion of acrAB homologs rendered V. vulnificus more susceptible to acriflavine only. Deletion of vexCD had no effect on susceptibility of V. vulnificus to these chemicals. Upon exposure to these antibacterial chemicals, expression of tolCV1 and tolCV2, which are putative outer membrane factors of RND efflux pumps, was induced, whereas expression levels of vexAB, vexCD, and acrAB homologs were not significantly changed. Our results show that the V. vulnificus homologs of VexAB largely contributed to in vitro antimicrobial resistance with a broad substrate specificity that was partially redundant with the AcrAB pump homologs.</P>
Lee, Hyo Jung,Kim, Jeong Myeong,Lee, Se Hee,Park, Minjeong,Lee, Kangseok,Madsen, Eugene L.,Jeon, Che Ok Microbiology Society 2011 Microbiology Vol.157 No.10
<P>Polaromonas naphthalenivorans strain CJ2 metabolizes naphthalene via the gentisate pathway and has recently been shown to carry a third copy of gentisate 1,2-dioxygenase (GDO), encoded by nagI3, within a previously uncharacterized naphthalene catabolic gene cluster. The role of this cluster (especially nagI3) in naphthalene metabolism of strain CJ2 was investigated by documenting patterns in regulation, transcription and enzyme activity. Transcriptional analysis of wild-type cells showed the third cluster to be polycistronic and that nagI3 was expressed at a relatively high level. Individual knockout mutants of all three nagI genes were constructed and their influence on both GDO activity and cell growth was evaluated. Of the three knockout strains, CJ2δnagI3 showed severely diminished GDO activity and grew slowest on aromatic substrates. These observations are consistent with the hypothesis that nagI3 may prevent toxic intracellular levels of gentisate from accumulating in CJ2 cells. All three nagI genes from strain CJ2 were cloned into Escherichia coli: the nagI2 and nagI3 genes were successfully overexpressed. The subunit mass of the GDOs were ~36-39 kDa, and their structures were deduced to be dimeric. The K(m) values of NagI2 and NagI3 were 31 and 10 ?M, respectively, indicating that the higher affinity of NagI3 for gentisate may protect the wild-type cells from gentisate toxicity. These results provide clues for explaining why the third gene cluster, particularly the nagI3 gene, is important in strain CJ2. The organization of genes in the third gene cluster matched that of clusters in Polaromonas sp. JS666 and Leptothrix cholodnii SP-6. While horizontal gene transfer (HGT) is one hypothesis for explaining this genetic motif, gene duplication within the ancestral lineage is equally valid. The HGT hypothesis was discounted by noting that the nagI3 allele of strain CJ2 did not share high sequence identity with its homologues in Polaromonas sp. JS666 and L. cholodnii SP-6.</P>