A5023619053- Antibiotic Resistance in Bacteria
- Bacterial Genetics and Biotechnology
- Antibiotics Pharmacokinetics and Efficacy
- Microbial infections and disease research
- Pneumonia and Respiratory Infections
- RNA and protein synthesis mechanisms
- Antimicrobial Resistance in Staphylococcus
- Bacteriophages and microbial interactions
- Bacterial biofilms and quorum sensing
- Evolution and Genetic Dynamics
- Antibiotic Use and Resistance
- Pharmaceutical and Antibiotic Environmental Impacts
- Photosynthetic Processes and Mechanisms
- Veterinary medicine and infectious diseases
- Plant nutrient uptake and metabolism
- Antimicrobial Peptides and Activities
- Origins and Evolution of Life
- CRISPR and Genetic Engineering
- Biochemical and Molecular Research
- Protein Structure and Dynamics
- Drug Transport and Resistance Mechanisms
- Microbial Natural Products and Biosynthesis
- RNA modifications and cancer
- Blood groups and transfusion
- Enzyme Structure and Function
Roche (Switzerland)
2018-2024
Purdue University West Lafayette
1996-2003
Harvard University
1996-1998
Oregon Health & Science University
1998
University of Bern
1991-1994
ABSTRACT We have developed a series of powerful and versatile conditional-replication, integration, modular (CRIM) plasmids. CRIM plasmids can be replicated at medium or high copy numbers in different hosts for making gene (or mutant) libraries. They integrated single copies into the chromosomes Escherichia coli related bacteria to study function under normal physiological conditions. excised from chromosome, e.g., verify that phenotypes are caused by their presence. Furthermore, they...
Abstract Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a major global pathogen with limited treatment options 1 . No new antibiotic chemical class activity against A. reached patients in over 50 years Here we report the identification and optimization of tethered macrocyclic peptide (MCP) antibiotics potent antibacterial CRAB. The mechanism action this molecule involves blocking transport bacterial lipopolysaccharide from inner membrane to its destination on outer...
ABSTRACT Escherichia coli genes regulated by environmental inorganic phosphate (P i ) levels form the (Pho) regulon. This regulation requires seven proteins, whose synthesis is under autogenous control, including response regulator PhoB, its partner, histidine sensor kinase PhoR, all four components of P -specific transport (Pst) system (PstA, PstB, PstC, and PstS), a protein unknown function called PhoU. Here we examined effects uncoupling PhoB PhoR from their normal controls placing each...
Iclaprim is a novel 2,4-diaminopyrimidine that exhibits potent, rapid bactericidal activity against major Gram-positive pathogens, including methicillin-susceptible Staphylococcus aureus and methicillin-resistant S. aureus, currently in clinical development for the treatment of complicated skin structure infections. An understanding known mechanism resistance to trimethoprim led design this new inhibitor, with improved affinity towards dihydrofolate reductase (DHFR) from clinically useful...
Diazabicyclooctanes (DBOs) are promising β-lactamase inhibitors. Some, including nacubactam (OP0595/RG6080), also bind PBP2 and have an enhancer effect, allowing activity against Enterobacteriaceae with MBLs, which DBOs do not inhibit. We tested the of nacubactam/β-lactam combinations MBL-producing Enterobacteriaceae.Test panels comprised (i) 210 consecutive NDM or VIM as referred by UK diagnostic laboratories, (ii) 99 supplementary Enterobacteriaceae, representing less prevalent phenotypes,...
Carbapenem-resistant Enterobacteriaceae (CRE) are resistant to most antibiotics, making CRE infections extremely difficult treat with available agents. Klebsiella pneumoniae carbapenemases (KPC-2 and KPC-3) predominant in the United States. Nacubactam is a bridged diazabicyclooctane (DBO) β-lactamase inhibitor that inactivates class A C β-lactamases exhibits intrinsic antibiotic β-lactam "enhancer" activity against In this study, we examined collection of meropenem-resistant K. isolates...
Abstract Beta-lactamase inhibitors are increasingly used to counteract antibiotic resistance mediated by beta-lactamase enzymes. These compete with the beta-lactam for same binding site on beta-lactamase, thus generating an evolutionary tradeoff: mutations that increase enzyme’s activity tend also its susceptibility inhibitor. Here, we investigate how common and accessible mutants escape this adaptive tradeoff. Screening a deep mutant library of bla ampC gene Escherichia coli , identified...
An Escherichia coli K-12 model system was developed for studying the VanS-VanR two-component regulatory required high-level inducible vancomycin resistance in Enterococcus faecium BM4147. Our is based on use of reporter strains with lacZ transcriptional and translational fusions to PvanR or PvanH promoter vanRSHAX gene cluster. These also express vanR vanS behind native promoter, arabinose-inducible ParaB rhamnose-inducible PrhaB promoter. have respective stably recombined onto chromosome...
Escherichia coli reporter strains modeling the high-level type A and B vancomycin resistances of Enterococcus faecium BM4147 Ent. faecalis have been developed to study respective VanR-VanS two-component regulatory systems. PvanH-, PvanRa-, PvanY-, PvanRb-lacZ fusions report on expression from vancomycin-resistant enterococci promoters vanRSHAXYZ vanRSYWHBX gene clusters. These also express single-copy chromosomal genes vanRa, vanRb, or vanRSb behind their promoter (PvanRa PvanRb) vanSa vanSb...
Two-component regulatory systems require highly specific interactions between histidine kinase (transmitter) and response regulator (receiver) proteins. We have developed a novel genetic strategy that is based on tightly regulated synthesis of given protein to identify domains residues an interacting are critical for them. Using reporter strain synthesizing the nonpartner VanS under tight arabinose control carrying promoter- lacZ fusion activated by phospho-PhoB, we isolated altered...
An enzymatic pathway for synthesis of 5-phospho-D-ribosyl alpha-1-diphosphate (PRPP) without the participation PRPP synthase was analyzed in Escherichia coli. This revealed by selection suppression NAD requirement strains with a deletion prs gene, gene encoding (B. Hove-Jensen, J. Bacteriol. 178:714-722, 1996). The new requires three enzymes: phosphopentomutase, ribose 1-phosphokinase, and 1,5-bisphosphokinase. latter activity is encoded phnN; product this required phosphonate degradation,...
Restriction enzyme digestion and field inversion gel electrophoresis were used to analyze the chromosomes of strains Mycoplasma hyopneumoniae related organism flocculare. The chromosome size for M. type strain was calculated from individual fragments be 1,011.3 +/- 32.9 kbp. approximately same size. restriction patterns obtained phenotypically similar quite different. Therefore, species seems very heterogeneous. A analysis entire allowed us distinguish easily hence characterize further...
The DNA sequence of the gene encoding early and specific immunogenic protein P36 Mycoplasma hyopneumoniae has been determined. Comparison deduced amino acid with known genes proteins in data banks indicated that is a L-lactate dehydrogenase (LDH) (EC 1.1.1.27). Biochemical analysis expressed from cloned Escherichia coli confirmed activity. Protein M. therefore termed LDH its ldh. was shown to contain typical domains other bacterial species. Immunologically however, we have polyclonal...
Diazabicyclooctanes (DBOs) are an increasingly important group of non β-lactam β-lactamase inhibitors, employed clinically in combinations such as ceftazidime/avibactam. The dose finding is complicated using the traditional pharmacokinetic/pharmacodynamic (PK/PD) index approach, especially if inhibitor has antibiotic effect its own.To develop a novel mechanism-based pharmacokinetic-pharmacodynamic (PKPD) model for ceftazidime/avibactam against Gram-negative pathogens, with potential...
Abstract Background Nacubactam (NAC, OP0595, RG6080) is a novel member of the diazabicyclooctane inhibitor family with dual mode action, acting as β-lactamase and an antibacterial agent by means PBP2 inactivation. NAC restores extends activity β-lactam antibiotics, such meropenem (MEM), when used in combination against variety carbapenem-resistant Enterobacteriaceae (CRE). The first year results ROSCO surveillance study for MEM/NAC contemporary clinical isolates are presented here. Methods...
ABSTRACT Iclaprim is a novel diaminopyrimidine antibiotic that active against methicillin-resistant Staphylococcus aureus (MRSA). However, it known the activity of diaminopyrimidines S. antagonized by thymidine through uptake and conversion to thymidylate kinase. Unlike with humans, for whom levels are low, in rodents high, thus precluding accurate evaluation iclaprim efficacy animal models. We have studied bactericidal an isogenic pair MRSA isolates, wild-type parent AW6 its...
Guanine or hypoxanthine, physiological corepressors of the Escherichia coli purine repressor (PurR), promote formation ternary PurR−corepressor−operator DNA complex that functions to repress pur operon gene expression. Structure-based predictions on importance Arg190 in determining 6−oxopurine specificity and corepressor binding affinity were tested by mutagenesis, analysis vivo function, vitro measurements. Replacements with Ala Gln resulted functional repressors which guanine hypoxanthine...
Abstract Beta-lactamase inhibitors are increasingly used to counteract microbial resistance beta-lactam antibiotics mediated by beta-lactamase enzymes. These compete with the drug for same binding site of beta-lactamase, thereby generating an inherent evolutionary tradeoff: enzyme mutations that increase its activity against also susceptibility towards inhibitor. It is unclear how common and accessible mutants escape this adaptive tradeoff. Here, systematically constructing phenotyping a...