Journal of Microbiology

Journal Articles

H-NS is a Transcriptional Repressor of the CRISPR-Cas System in Acinetobacter baumannii ATCC 19606: Kyeongmin Kim, Md Maidul Islam, Seunghyeok Bang, Jeongah Kim, Chung-Young Lee, Je Chul Lee, Minsang Shin; J. Microbiol. 2024;62(11):999-1012. Published online November 11, 2024; DOI: https://doi.org/10.1007/s12275-024-00182-5

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Abstract: Acinetobacter baumannii is a multidrug-resistant opportunistic pathogen primarily associated with hospital-acquired infections. The bacterium can gain multidrug resistance through several mechanisms, including horizontal gene transfer. A CRISPR-Cas system including several Cas genes could restrict the horizontal gene transfer. However, the molecular mechanism of CRISPR- Cas transcriptional regulation remains unclear. We identified a type I-F CRISPR-Cas system in A. baumannii ATCC 19606^T standard strain based on sequence analysis. We focused on the transcriptional regulation of Cas3, a key protein of the CRISPR-Cas system. We performed a DNA affinity chromatography-pulldown assay to identify transcriptional regulators of the Cas3 promoter. We identified several putative transcriptional factors, such as H-NS, integration host factor, and HU, that can bind to the promoter region of Cas3. We characterized AbH-NS using size exclusion chromatography and cross-linking experiments and demonstrated that the Cas3 promoter can be regulated by AbH-NS in a concentration-dependent manner via an in vitro transcription assay. CRISPR-Cas expression levels in wild-type and hns mutant strains in the early stationary phase were examined by qPCR and β-galactosidase assay. We found that H-NS can act as a repressor of Cas3. Our transformation efficiency results indicated that the hns mutation decreased the transformation efficiency, while the Cas3 mutation increased it. We report the existence and characterization of the CRISPR-Cas system in A. baumannii 19606^T and demonstrate that AbH-NS is a transcriptional repressor of CRISPR-Cas-related genes in A. baumannii.

Amino acid residues in the Ler protein critical for derepression of the LEE5 promoter in enteropathogenic E. coli: Su-Mi Choi , Jae-Ho Jeong , Hyon E. Choy , Minsang Shin; J. Microbiol. 2016;54(8):559-564. Published online August 2, 2016; DOI: https://doi.org/10.1007/s12275-016-6027-6

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Enteropathogenic E. coli causes attaching and effacing (A/E) intestinal lesions. The genes involved in the formation of A/E lesions are encoded within a chromosomal island comprising of five major operons, LEE1-5. The global regulator H-NS represses the expression of these operons. Ler, a H-NS homologue, counteracts the H-NS–mediated repression. Using a novel genetic approach, we identified the amino acid residues in Ler that are involved in the interaction with H-NS: I20 and L23 in the C-terminal portion of α-helix 3, and I42 in the following unstructured linker region.

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Regulation of the Locus of Enterocyte Effacement in Attaching and Effacing Pathogens
R. Christopher D. Furniss, Abigail Clements, William Margolin
Journal of Bacteriology.2018;[Epub] CrossRef

Research Support, Non-U.S. Gov't

Note] Identification of High-Specificity H-NS Binding Site in LEE5 Promoter of Enteropathogenic Esherichia coli (EPEC): Abhay Prasad Bhat , Minsang Shin , Hyon E. Choy; J. Microbiol. 2014;52(7):626-629. Published online March 7, 2014; DOI: https://doi.org/10.1007/s12275-014-3562-x

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Abstract

Histone-like nucleoid structuring protein (H-NS) is a small but abundant protein present in enteric bacteria and is involved in compaction of the DNA and regulation of the transcription. Recent reports have suggested that H-NS binds to a specific AT rich DNA sequence than to intrinsically curved DNA in sequence independent manner. We detected two high-specificity H-NS binding sites in LEE5 promoter of EPEC centered at -110 and -138, which were close to the proposed consensus H-NS binding motif. To identify H-NS binding sequence in LEE5 promoter, we took a random mutagenesis approach and found the mutations at around -138 were specifically defective in the regulation byH-NS. It was concluded that H-NS exertsmaximumrepression via the specific sequence at around -138 and ubsequently contacts α subunit of RNAP through oligomerization.

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Horizontally Acquired Homologs of Xenogeneic Silencers: Modulators of Gene Expression Encoded by Plasmids, Phages and Genomic Islands
Alejandro Piña-Iturbe, Isidora D. Suazo, Guillermo Hoppe-Elsholz, Diego Ulloa-Allendes, Pablo A. González, Alexis M. Kalergis, Susan M. Bueno
Genes.2020; 11(2): 142. CrossRef
Recent advances in genetic engineering tools based on synthetic biology
Jun Ren, Jingyu Lee, Dokyun Na
Journal of Microbiology.2020; 58(1): 1. CrossRef
Regulation of the Locus of Enterocyte Effacement in Attaching and Effacing Pathogens
R. Christopher D. Furniss, Abigail Clements, William Margolin
Journal of Bacteriology.2018;[Epub] CrossRef
Bacterial-Chromatin Structural Proteins Regulate the Bimodal Expression of the Locus of Enterocyte Effacement (LEE) Pathogenicity Island in Enteropathogenic Escherichia coli
Hervé Leh, Ahmad Khodr, Marie-Christine Bouger, Bianca Sclavi, Sylvie Rimsky, Stéphanie Bury-Moné, Susan Gottesman
mBio.2017;[Epub] CrossRef
Alternative Synthesis Route of Biocompatible Polyvinylpyrrolidone Nanoparticles and Their Effect on Pathogenic Microorganisms
Vedran Milosavljevic, Pavlina Jelinkova, Ana Maria Jimenez Jimenez, Amitava Moulick, Yazan Haddad, Hana Buchtelova, Sona Krizkova, Zbynek Heger, Lukas Kalina, Lukas Richtera, Pavel Kopel, Vojtech Adam
Molecular Pharmaceutics.2017; 14(1): 221. CrossRef
H-NS and RNA polymerase: a love–hate relationship?
Robert Landick, Joseph T Wade, David C Grainger
Current Opinion in Microbiology.2015; 24: 53. CrossRef
Effect of promoter-upstream sequence on σ38-dependent stationary phase gene transcription
Hyung-Ju Lim, Kwangsoo Kim, Minsang Shin, Jae-Ho Jeong, Phil Youl Ryu, Hyon E. Choy
Journal of Microbiology.2015; 53(4): 250. CrossRef

Identification of the Genes Involved in Stationary-Phase Specific Acid Resistance of Salmonella typhimurium: Bang, Iel Soo , Lee, In Soo , Lee, Yung Nok , Park, Yong keun; J. Microbiol. 1995;33(1):21-27.

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Abstract: Salmonella encounters variables pH fluctuation during its life cycle and has been developed adaptative systems such as acid tolerance response (ATR) to survive at severe acidic environment. As part of on going investigation of stationary-phase specific acid resistance, we have searched for acid sensitive mutations in virulent Salmonella typhimurim UK-1 usin the MudJ fusion technique and two lethal selection procedures including DNP(dinitrophenol) selection media and microtiterplate selection method. Two acid sensitive mutations have been identified and designated, spatrK2, spatrK5. These mutations removed both stationary-phase acid tolerant effect and stationary-phase specific acid resistance. Non-specific histone like protein, H-NS and stationary-phase specific sigma factor, RpoS made little contribution to that system at respective single mutation(5-10 fold decrease). But, when both mutations were combined together, no acid resistance was achieved while acid tolerance response was still effective. Two dimensional SDS polyacrylamide gel electrophoresis showed new stationary-phase specific acid shock proteins as well as proteins already known. Not expectedly, the gels from acid adapted samples of both rpoS and hns mutation showed that double mutation of those regulators does not make change of the standard acid shock proteins. Only four acid shock proteins were regulated by these regulators, while fifteen proteins were newly identified as the members of acid shock response system by these regulators. These results implicate that stationary-phase acid resistance of that organism has RpoS/H-NS soubly dependent acid protective system and independent acid tolerance response system.

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