• Journal of Microbiology and Biotechnology
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• v.29 no.12
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• pp.1916-1924
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• 2019

Outbreaks of staphylococcal food poisoning (SFP) causing serious human diseases and economic losses have been reported globally. Furthermore, the spread of Staphylococcus aureus with increased resistance to multiple antimicrobial agents has become a major concern in the food industries and medicine. Here, we isolated an endolysin LysSAP8, as one of the peptidoglycan hydrolases, derived from the bacteriophage SAP8 infecting S. aureus. This endolysin was tagged with a 6×His at the C-terminal of the target protein and purified using affinity chromatography. LysSAP8 demonstrated lytic activity against a broad spectrum of bacteria, which included a majority of the staphylococcal strains tested in this study as well as the methicillin-resistant S. aureus (MRSA); however, no such activity was observed against other gram-positive or gram-negative bacteria. Additionally, LysSAP8 could maintain bactericidal activity until 0.1 nM working concentration and after heat treatment at 37℃ for 30 min. The ability of LysSAP8 to lyse cells under varying conditions of temperature (4-43℃), pH (3-9), and NaCl concentrations (0-1,000 mM), and divalent metal ions (Ca²⁺, Co²⁺, Cu²⁺, Mg²⁺, Mn²⁺, Hg²⁺, and Zn²⁺) was examined. At the optimized condition, LysSAP8 could disrupt approximately 3.46 log CFU/ml of the planktonic cells in their exponential phase of growth within 30 min. In this study, we have suggested that LysSAP8 could be a potent alternative as a biocontrol agent that can be used to combat MRSA.

• Bulletin of the Korean Chemical Society
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• v.31 no.6
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• pp.1519-1526
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• 2010

The behavior of peptide or protein solutes in saline aqueous solution is a fundamental topic in physical chemistry. Addition of ions can strongly alter the thermodynamic and physical properties of peptide molecules in solution. In order to study the effects of added ionic salts on protein conformation and dynamics, we have used the molecular dynamics (MD) simulations to investigate the behavior of Staphylococcus aureus Hfq protein under two different ionic concentrations: 0.1 M NaCl and 1.0 M NaCl in presence and absence of RNA (a hepta-oligoribonucleotide AU5G). Hfq, a global regulator of gene expression is highly conserved and abundant RNA-binding protein. It is already reported that in vivo the increase of ionic strength results in a drastic reduction of Hfq affinity for $Q{\beta}$ RNA and reduces the tendency of aggregation of Escherichia coli host factor hexamers. Our results revealed the crucial role of 0.1 M NaCl Hfq system on the bases with strong hydrogen bonding interactions and by stabilizing the aromatic stacking of Tyr42 residue of the adjacent subunits/monomers with the adenine and uridine nucleobases. An increase in RNA pore diameter and weakened compactness of the Hfq-RNA complex was clearly observed in 1.0 M NaCl Hfq system with bound RNA. Aggregation of monomers in Hfq and the interaction of Hfq with RNA are greatly affected due to the presence of high ionic strength. Higher the ionic concentration, weaker is the aggregation and interaction. Our results were compatible with the experimental data and this is the first theoretical report for the experimental study done in 1980 by Uhlenbeck group for the present system.

• Journal of Microbiology
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• v.45 no.4
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• pp.350-357
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• 2007

This study was conducted in an effort to evaluate the antimicrobial activity and antibiotic-resistant gene regulation from Saliva miltiorrhiza Bunge on methicillin-resistant Staphylococcus aureus (MRSA). A variety of solvent fractions and methanol extracts of S. miltiorrhiza Bunge were tested in order to determine its antimicrobial activities against S. aureus and MRSA. As a result, the hexane fraction of S. miltiorrhiza Bunge evidenced the highest levels of antimicrobial activity against S. aureus and MRSA. The MICs of the hexane fraction against various MRSA specimens were $64. The hexane fraction evidenced inhibitory effects superior to those of the chloroform fraction. The results showed inhibition zones of hexane (16 mm) and chloroform (14 mm) fractions against MRSA KCCM 40511 at $1,000{\mu}g/disc$. The hexane and chloroform fractions inhibited the expression of the resistant genes, mecA, mecR1, and femA in mRNA. Moreover, the results of Western blotting assays indicated that the hexane and chloroform fractions inhibited the expression of the resistant protein, PBP2a. These results reveal that the hexane and chloroform fractions of S. miltiorrhiza Bunge may prove to be a valuable choice for studies targeted toward the development of new antimicrobial agents.

• Biodesign
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• v.6 no.4
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• pp.96-99
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• 2018

The gram-positive bacterium Staphylococcus aureus is a common cause of abscesses, sinusitis and food poisoning. The emergence of antibiotic-resistant strains has caused significant clinical issues worldwide. The HslU-HslV complex was first identified as a prokaryotic homolog of eukaryotic proteasomes. HslU is an unfoldase that mediates the unfolding of the substrate proteins, and it works with the protease HslV in the complex. To date, the protein complex has been mostly studied in gram-negative bacteria. In this study, we report the purification and crystallization of the full-length HslU from S. aureus. The crystal diffracted X-rays to a $3.5{\AA}$ resolution, revealing that the crystals belong to space group $P2_1$, with unit cell parameters of a = 166.5, b = 189.6, $c=226.6{\AA}$, and ${\beta}=108.1^{\circ}$. We solved the phage problem by molecular replacement using the structure of HslU from Haemophilus influenzae as a search model. The cell content analysis with this molecular replacement solution revealed that 24 molecules are contained in the asymmetric unit. This structure provides insight into the structural and mechanistic difference of the HslUV complex of gram-positive bacteria.

• The Journal of the Korean Society for Microbiology
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• v.21 no.1
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• pp.145-149
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• 1986

The development of delayed-type hypersensitivity(DTH) reaction to Staphylococcus aureus in mice was studied, Mice received 3 injections of $10^8$ viable S. aureus subcutaneously showed a marked footpad swelling when mice were challenged with $10\;{\mu}g$ staphylococcal protein antigen into footpad(The percent increase of footpad thickness at 24 h after challenge wsa 35% approximately). Histological observation of footpad of immunized mice showed a marked thickness of subcutaneous tissue due to edematous reaction and massive infiltration of lymphocytes and neutrophils which are characteristic cells in DTH reaction. Intensity of DTH reaction of mice immunized with viable bacteria was much higher than that of mice immunized with staphylococcal protein or heat-killed bacteria. The DTH reaction to S. aureus could be transferred to normal recipient mice by both spleen cells and lymph node cells.

• Journal of Biomedical Engineering Research
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• v.34 no.3
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• pp.123-128
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• 2013

The 'Dielectrophoretic Tweezers(DEP Tweezers)' can be used as a facile, economical toolkit for quantitative measurement of chemical and biological binding forces related to many biological interactions within a microfluidic device. Our experimental setup can probe the interaction between a single receptor molecule and its specific ligand. Immunoglobulin G(IgG) functionalized on polystyrene microspheres has been used to detect individual surface linked Staphylococcus protein A(SpA) molecules and to characterize the strength of the noncovalent IgG-SpA bond. It was measured and compared with the existing measurements. Measured single binding force of between Goat, Rabbit IgG and SpA were $17{\pm}7pN$, $74{\pm}16pN$. This work can be used to investigate several different ligand-receptor interactions and antigen-antibody interactions.

• Parasites, Hosts and Diseases
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• v.60 no.1
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• pp.7-14
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• 2022

Acanthamoeba keratitis (AK) is a rare infectious disease and accurate diagnosis has remained arduous as clinical manifestations of AK were similar to keratitis of viral, bacterial, or fungal origins. In this study, we described the production of a polyclonal peptide antibody against the adenylyl cyclase-associated protein (ACAP) of A. castellanii, and evaluated its differential diagnostic potential. Enzyme-linked immunosorbent assay revealed high titers of A. castellanii-specific IgG and IgA antibodies being present in low dilutions of immunized rabbit serum. Western blot analysis revealed that the ACAP antibody specifically interacted with A. castellanii, while not interacting with human corneal epithelial (HCE) cells and other causes of keratitis such as Fusarium solani, Pseudomonas aeruginosa, and Staphylococcus aureus. Immunocytochemistry (ICC) results confirmed the specific detection of trophozoites and cysts of A. castellanii co-cultured with HCE cells. The ACAP antibody also specifically interacted with the trophozoites and cysts of 5 other Acanthamoeba species. These results indicate that the ACAP antibody of A. castellanii can specifically detect multiple AK-causing members belonging to the genus Acanthamoeba and may be useful for differentially diagnosing Acanthamoeba infections.

• Genomics & Informatics
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• v.21 no.3
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• pp.34.1-34.10
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• 2023

Nosocomial infections, commonly referred to as healthcare-associated infections, are illnesses that patients get while hospitalized and are typically either not yet manifest or may develop. One of the most prevalent nosocomial diseases in hospitalized patients is pneumonia, among the leading causes of mortality and morbidity. Viral, bacterial, and fungal pathogens cause pneumonia. More severe introductions commonly included Staphylococcus aureus, which is at the top of bacterial infections, per World Health Organization reports. The staphylococci, S. aureus, strain RMI-014804, mesophile, on-sporulating, and non-motile bacterium, was isolated from the sputum of a pulmonary patient in Pakistan. Many characteristics of S. aureus strain RMI-014804 have been revealed in this paper, with complete genome sequence and annotation. Our findings indicate that the genome is a single circular 2.82 Mbp long genome with 1,962 protein-coding genes, 15 rRNA, 49 tRNA, 62 pseudogenes, and a GC content of 28.76%. As a result of this genome sequencing analysis, researchers will fully understand the genetic and molecular basis of the virulence of the S. aureus bacteria, which could help prevent the spread of nosocomial infections like pneumonia. Genome analysis of this strain was necessary to identify the specific genes and molecular mechanisms that contribute to its pathogenicity, antibiotic resistance, and genetic diversity, allowing for a more in-depth investigation of its pathogenesis to develop new treatments and preventive measures against infections caused by this bacterium.

• Journal of Microbiology and Biotechnology
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• v.23 no.2
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• pp.184-188
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• 2013

In the continued search for inhibitors of enoyl-acyl carrier protein (ACP) reductase, we found that four acylbenzenediol sulfate metabolites from Streptomyces sp. AN1761 potently inhibited bacterial enoyl-ACP reductases of Staphylococcus aureus, Streptococcus pneumoniae, and Mycobacterium tuberculosis. Their structures were identified as panosialins A, B, wA, and wB by MS and NMR data. They showed stronger inhibition against S. aureus FabI and S. pneumoniae FabK with $IC_{50}$ of 3-5 ${\mu}M$ than M. tuberculosis InhA with $IC_{50}$ of 9-12 ${\mu}M$. They also exhibited a stronger antibacterial spectrum on S. aureus and S. pneumoniae than M. tuberculosis. In addition, the higher inhibitory activity of panosialin wB than panosialin B on fatty acid biosynthesis was consistent with that on bacterial growth, suggesting that they could exert their antibacterial activity by inhibiting fatty acid synthesis.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.1
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• pp.35-42
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• 2015

Purpose: The present study was aimed to compare the difference in adherence level of microorganisms according to contact lens materials and protein deposition and to evaluate disinfection efficacy of multipurpose solution. Methods: The evaluations of micro-organisms' adherence and disinfection efficacy of multi-purpose solution were conducted by employing the Part 2. Regimen Procedure for Disinfecting Regiments in the Disinfection Efficacy Testing under the "FDA Evaluation Criteria & Method". Results: Pseudomonas aeruginosa, Serratia marcescens, Candida albicans except Staphylococcus aureus adhered more on etafilcon A lens and disinfection efficacy of total 4 products investigated was almost perfect except Candida albicans. The 3 micro-organisms except Serratia marcescens adhered more to albumin-predeposited lens. Disinfection efficacy of multi-purpose solution was higher against the micro-organisms adhered to albumin-deposited lens than against the micro-organisms adhered to the lysozyme-deposited lens. Furthermore, disinfection efficacy of multi-purpose solution was different according to types of micro-organisms. Conclusions: It was revealed that the type of micro-organisms, the lens materials and type of absorbed tear protein affected the amount of adhered micro-organisms to contact lens and that adhesion of tear protein could induce the change of disinfection efficacy of multi-purpose solution. It suggest that the hygienic condition of contact lens can vary by these factors influencing on disinfection efficacy and the occurrence of adverse effect can be affected.