Journal of Microbiology

Review

[MINIREIVEW] Anti-MRSA agent discovery using Caenorhabditis elegans-based high-throughput screening: Soo Min Kim , Iliana Escorbar , Kiho Lee , Beth Burgwyn Fuchs , Eleftherios Mylonakis , Wooseong Kim; J. Microbiol. 2020;58(6):431-444. Published online May 27, 2020; DOI: https://doi.org/10.1007/s12275-020-0163-8

Abstract: Staphylococcus aureus is a leading cause of hospital- and community- acquired infections. Despite current advances in antimicrobial chemotherapy, the infections caused by S. aureus remain challenging due to their ability to readily develop resistance. Indeed, antibiotic resistance, exemplified by methicillin- resistant S. aureus (MRSA) is a top threat to global health security. Furthermore, the current rate of antibiotic discovery is much slower than the rate of antibiotic-resistance development. It seems evident that the conventional in vitro bacterial growth-based screening strategies can no longer effectively supply new antibiotics at the rate needed to combat bacterial antibiotic-resistance. To overcome this antibiotic resistance crisis, screening assays based on host–pathogen interactions have been developed. In particular, the free-living nematode Caenorhabditis elegans has been used for drug screening against MRSA. In this review, we will discuss the general principles of the C. elegans-based screening platform and will highlight its unique strengths by comparing it with conventional antibiotic screening platforms. We will outline major hits from high-throughput screens of more than 100,000 small molecules using the C. elegans–MRSA infection assay and will review the mode-of-action of the identified hit compounds. Lastly, we will discuss the potential of a C. elegansbased screening strategy as a paradigm shift screening platform.

Journal Article

Cyclooxygenase Inhibitors Reduce Biofilm Formation and Yeast-Hypha Conversion of Fluconazole Resistant Candida albicans: E. Abdelmegeed , Mona Ibrahim Shaaban; J. Microbiol. 2013;51(5):598-604. Published online September 14, 2013; DOI: https://doi.org/10.1007/s12275-013-3052-6

Abstract: The incidence of fluconazole-resistant Candida albicans has been increasing worldwide. Both biofilm and fungal morphogenesis are main virulence factors of C. albicans cells. Extracellular fungal prostaglandins are synthesized during biofilm adhesion and development and through yeast-hypha conversion. Hence, we targeted prostaglandin synthesis with various cyclooxygenase (COX) inhibitors (aspirin, diclofenac, ketoprofen, tenoxicam, and ketorolac) and assessed their effect on fungal adhesion, biofilm formation, and yeast-hypha conversion in clinical isolates of Fluconazole resistant C. albicans. Significant reduction in fungal adhesion and detachment of mature biofilm was attained down to 1 mM concentrations of anti-inflammatory agents. Microscopical examination of fungal cells in the presence of the tested drugs showed significant reduction of germ tube formation. Therefore, COX inhibitors have a significant effect on reduction of Candida adhesion and biofilm development in correlation with fungal morphogenesis. Moreover, inhibition of C. albicans by COX inhibitors gave synergistic activity with fluconazole suggesting that combination therapeutic strategies may be fruitful for management of infection of Fluconazole resistant C. albicans.

Partial purification and characterization of β-ketothiolase from Alcaligenes sp. SH-69: Oh, Deok Hwan , Chung, Chung Wook , Kim, Jeong Yoon , Rhee, Young Ha; J. Microbiol. 1997;35(4):360-364.

Abstract: A β-ketothiolase was purified 180-fold from the cell extracts of Alcaligenes sp. SH-69 by a series of chromatography on DEAE-Dephadex A-50, Sephacryl S-200, and hydrozyapatitie columns, The optimum pH values of the partially purified enzyme were 7.5 for condensation reaction and 8.3 for thiolysis reaction. The K_m valued for acetoacetyl-CoA and free CoASH in the thiolusis in the condensation reaction was 0.70mM. The condensation reaction of the β-ketothiolase was inhibited even by low concentrations of free CoASH(K_I= 30.4 uM). Pretreatment of the enzyme with NADH and NADPH markedly inhibited the thiolysis reaction of the enzyme. The potent inhibition of the enzyme by sulfhydryl reagents suggests the involvement of cystein residue in the active site.

A Recombinant Human [alpha]_1-Antitrypsin Variant, M_malton, Undergoes a Spontaneous Conformational Conversion into a Latent Form: Chan-Hun Jung , Hana Im; J. Microbiol. 2003;41(4):335-339.

Abstract: Many genetic variants of [alpha]_1-antitrypsin have been associated with early onset emphysema and liver cirrhosis. However, the detailed structural basis of pathogenic [alpha]_1-antitrypsin molecules is rarely known. Here we found that a recombinant M_malton variant (Phe52-deleted) lost inhibitory activity by spontaneous conformational conversion into a more stable, inactive form under physiological conditions. Biochemical and spectroscopic data suggested that the variant converts into a reactive center loop-inserted conformation, resembling the latent form of plasminogen activator inhibitor-1.

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