Methionine aminopeptidase as a novel Target for antibiotic therapy against staphylococcus aureus: a proteomic approach

Key Messages 1. Methionine aminopeptidase (MetAP) is an essential enzyme in Staphylococcus aureus and a potential target for novel antibiotics. 2. Two-dimensional electrophoresis gel identified more than 100 differences in protein expression between wild type and MetAP-deficient strains of S aureus. 3. Using mass spectroscopic techniques, 63 differentially expressed proteins were identified, of which some were related to purine biosynthesis and methionine metabolism.published_or_final_versio

Identification of Novel Small Organic Compounds with Diverse Structures for the Induction of Epstein-Barr Virus (EBV) Lytic Cycle in EBV-Positive Epithelial Malignancies

Phorbol esters, which are protein kinase C (PKC) activators, and histone deacetylase (HDAC) inhibitors, which cause enhanced acetylation of cellular proteins, are the main classes of chemical inducers of Epstein-Barr virus (EBV) lytic cycle in latently EBV-infected cells acting through the PKC pathway. Chemical inducers which induce EBV lytic cycle through alternative cellular pathways may aid in defining the mechanisms leading to lytic cycle reactivation and improve cells’ responsiveness towards lytic induction. We performed a phenotypic screening on a chemical library of 50,240 novel small organic compounds to identify novel class(es) of strong inducer(s) of EBV lytic cycle in gastric carcinoma (GC) and nasopharyngeal carcinoma (NPC) cells. Five hit compounds were selected after three successive rounds of increasingly stringent screening. All five compounds are structurally diverse from each other and distinct from phorbol esters or HDAC inhibitors. They neither cause hyperacetylation of histone proteins nor significant PKC activation at their working concentrations, suggesting that their biological mode of action are distinct from that of the known chemical inducers. Two of the five compounds with rapid lytic-inducing action were further studied for their mechanisms of induction of EBV lytic cycle. Unlike HDAC inhibitors, lytic induction by both compounds was not inhibited by rottlerin, a specific inhibitor of PKCδ. Interestingly, both compounds could cooperate with HDAC inhibitors to enhance EBV lytic cycle induction in EBV-positive epithelial cancer cells, paving way for the development of strategies to increase cells’ responsiveness towards lytic reactivation. One of the two compounds bears structural resemblance to iron chelators and the other strongly activates the MAPK pathways. These structurally diverse novel organic compounds may represent potential new classes of chemicals that can be used to investigate any alternative mechanism(s) leading to EBV lytic cycle reactivation from latency.published_or_final_versio

Construction of a Multiplex Promoter Reporter Platform to Monitor Staphylococcus aureus Virulence Gene Expression and the Identification of Usnic Acid as a Potent Suppressor of psm Gene Expression

As antibiotic resistance becomes phenomenal, alternative therapeutic strategies for bacterial infections such as anti-virulence treatments have been advocated. We have constructed a total of 20 gfp-luxABCDE dual-reporter plasmids with selected promoters from S. aureus virulence-associated genes. The plasmids were introduced into various S. aureus strains to establish a gfp-lux based multiplex promoter reporter platform for monitoring S. aureus virulence gene expressions in real time to identify factors or compounds that may perturb virulence of S. aureus. The gene expression profiles monitored by luminescence correlated well with qRT-PCR results and extrinsic factors including carbon dioxide and some antibiotics were shown to suppress or induce the expression of virulence factors in this platform. Using this platform, sub-inhibitory ampicillin was shown to be a potent inducer for the expression of many virulence factors in S. aureus. Bacterial adherence and invasion assays using mammalian cells were employed to measure S. aureus virulence induced by ampicillin. The platform was used for screening of natural extracts that perturb the virulence of S. aureus and usnic acid was identified to be a potent repressor for the expression of psm.published_or_final_versio

Structural Characterization of H1N1 Nucleoprotein-Nucleozin Binding Sites

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Improving quality of life through reducing post-operative bacterial infections

Session: Functionalization of Cells and Biomaterials: abstract no. 483INTRODUCTION: Metallic implants such as titanium alloy have been widely used in orthopaedic surgeries1. 2-5% of the patients acquire post-operative bacterial infections at implant site though prescription of antibiotics2. Patients may suffer from surgeries like debridement of wound, removal of problematic implant and insertion of new implant. To reduce bacterial infections and improve quality of life of patients, implant surfaces loaded with …postprintThe 2010 North America Conference of the Tissue Engineering and Regenerative Medicine International Society (TERMIS-NA 2010), Orlando, FL., 5-8 December 2010

A DNA vaccine targeting TcdA and TcdB induces protective immunity against Clostridium difficile

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HKOCl-3: a fluorescent hypochlorous acid probe for live-cell and in vivo imaging and quantitative application in flow cytometry and a 96-well microplate assay

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Natural products triptolide, celastrol, and withaferin A inhibit the chaperone activity of peroxiredoxin I

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Identification of catabolite control protein A from Staphylococcus aureus as a target of silver ions

Staphylococcus aureus is one of the most common pathogenic bacteria that causes human infectious diseases. The emergence of antibiotic-resistant strains of S. aureus promotes the development of new anti-bacterial strategies. Silver ions (Ag+) have attracted profound attention due to their broad-spectrum antimicrobial activities. Although the antibacterial properties of silver have been well known for many centuries, its mechanism of action remains unclear and its protein targets are rarely reported. Herein, we identify the catabolite control protein A (CcpA) of S. aureus as a putative target for Ag+. CcpA binds 2 molar equivalents of Ag+ via its two cysteine residues (Cys216 and Cys242). Importantly, Ag+ binding induces CcpA oligomerization and abolishes its DNA binding capability, which further attenuates S. aureus growth and suppresses a-hemolysin toxicity. This study extends our understanding of the bactericidal effects of silver.published_or_final_versio

Immunotherapy Targeting Adenosine Synthase A Decreases Severity of Staphylococcus aureus Infection in Mouse Model

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