Journal of Microbiology

Ji-Hoon Kim

1 Article

Genomic Organization of Penicillium chrysogenum chs4, a Class III Chitin Synthase Gene: Yoon-Dong Park , Myung-Sook Lee , Ji-Hoon Kim , Jun Namgung , Bum Chan Park , Kyung Sook Bae , Hee-Moon Park; J. Microbiol. 2000;38(4):230-238.

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Abstract: Class III chitin synthases in filamentous fungi are important for hyphal growth and differentiation of several filamentous fungi. A genomic clone containing the full gene encoding Chs4, a class III chitin synthase in Penicillium chrysogenum, was cloned by PCR screening and colony hybridization from the genomic library. Nucleotide sequence analysis and transcript mapping of chs4 revealed an open reading frame (ORF) that consisted of 5 exons and 4 introns and encoded a putative protein of 915 amino acids. Nucleotide sequence analysis of the 5?lanking region of the ORF revealed a potential TATA box and several binding sites for transcription activators. The putative transcription initiation site at ?6 position was identified by primer extension and the expression of the chs4 during the vegetative growth was confirmed by Northern blot analysis. Amino acid sequence analysis of the Chs4 revealed at least 5 transmembrane helices and several sites for post-translational modifications. Comparison of the amino acid sequence of Chs4 with those of other fungi showed a close relationship between P. chr ysogenum and genus Aspergillus.

Ji-Hoon Kim

1 Article

Repeated Exposure of Vancomycin to Vancomycin-Susceptible Staphylococcus aureus (VSSA) Parent Emerged VISA and VRSA Strains with Enhanced Virulence Potentials: An Nguyen, J Jean Sophy Roy, Ji-Hoon Kim, Kyung-Hee Yun, Wonsik Lee, Kyeong Kyu Kim, Truc Kim, Akhilesh Kumar Chaurasia; J. Microbiol. 2024;62(7):535-553. Published online May 30, 2024; DOI: https://doi.org/10.1007/s12275-024-00139-8

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Abstract

The emergence of resistance against the last-resort antibiotic vancomycin in staphylococcal infections is a serious concern for human health. Although various drug-resistant pathogens of diverse genetic backgrounds show higher virulence potential, the underlying mechanism behind this is not yet clear due to variability in their genetic dispositions. In this study, we investigated the correlation between resistance and virulence in adaptively evolved isogenic strains. The vancomycin-susceptible Staphylococcus aureus USA300 was exposed to various concentrations of vancomycin repeatedly as a mimic of the clinical regimen to obtain mutation(s)-accrued-clonally-selected (MACS) strains. The phenotypic analyses followed by expression of the representative genes responsible for virulence and resistance of MACS strains were investigated. MACS strains obtained under 2 and 8 µg/ml vancomycin, named Van2 and Van8, respectively; showed enhanced vancomycin minimal inhibitory concentrations (MIC) to 4 and 16 µg/ml, respectively. The cell adhesion and invasion of MACS strains increased in proportion to their MICs. The correlation between resistance and virulence potential was partially explained by the differential expression of genes known to be involved in both virulence and resistance in MACS strains compared to parent S. aureus USA300. Repeated treatment of vancomycin against vancomycin-susceptible S. aureus (VSSA) leads to the emergence of vancomycin-resistant strains with variable levels of enhanced virulence potentials.

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Targeting the G-quadruplex as a novel strategy for developing antibiotics against hypervirulent drug-resistant Staphylococcus aureus
Maria Sultan, Maria Razzaq, Joohyun Lee, Shreyasi Das, Shrute Kannappan, Vinod Kumar Subramani, Wanki Yoo, Truc Kim, Hye-Ra Lee, Akhilesh K. Chaurasia, Kyeong Kyu Kim
Journal of Biomedical Science.2025;[Epub] CrossRef

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