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https://www.readbyqxmd.com/read/29335824/broad-spectrum-resistance-of-pseudomonas-aeruginosa-from-shellfish-infrequent-acquisition-of-novel-resistance-mechanisms
#1
Ana Maravić, Ivica Šamanić, Matilda Šprung, Željana Fredotović, Nada Ilić, Josipa Dragičević, Jasna Puizina
Pseudomonas aeruginosa is one the most common multidrug-resistant pathogens worldwide. It has been previously detected in marine shellfish, but its antibiotic resistance in such environment has not been explored. By combining PCR detection of acquired genes, and resistance-nodulation-cell division (RND) efflux studying, we investigated the multifactorial resistance traits of 108 P. aeruginosa isolates recovered from wild-growing Mediterranean mussels (Mytilus galloprovincialis) in Croatia. Eleven different resistance profiles were found, with the main mechanism being the overexpression of intrinsic efflux pump(s), particularly MexAB-OprM...
January 15, 2018: Environmental Monitoring and Assessment
https://www.readbyqxmd.com/read/29304169/the-vibrio-cholera-rnd-efflux-systems-impact-virulence-factor-production-and-adaptive-responses-via-periplasmic-sensor-proteins
#2
X Renee Bina, Mondraya F Howard, Dawn L Taylor-Mulneix, Vanessa M Ante, Dillon E Kunkle, James E Bina
Resistance-nodulation-division (RND) efflux systems are ubiquitous transporters in Gram-negative bacteria that are essential for antibiotic resistance. The RND efflux systems also contribute to diverse phenotypes independent of antimicrobial resistance, but the mechanism by which they affect most of these phenotypes is unclear. This is the case in Vibrio cholerae where the RND systems function in antimicrobial resistance and virulence factor production. Herein, we investigated the linkage between RND efflux and V...
January 5, 2018: PLoS Pathogens
https://www.readbyqxmd.com/read/29299916/towards-eco-friendly-and-highly-efficient-solar-water-splitting-using-in2s3-anatase-rutile-tio2-dual-staggered-heterojunction-nanodendrite-array-photoanode
#3
Jih-Sheng Yang, Jih-Jen Wu
The TiO2-based heterojunction nanodendrite (ND) array composed of anatase NPs (ANP) on the surface of rutile ND (RND) array is selected as the model photoanode to demonstrate the strategies towards eco-friendly and efficient solar water splitting using neutral electrolyte and seawater. Compared to the performances in alkaline electrolyte, non-negligible potential drop across the electrolyte as well as impeded charge injection and charge separation are monitored in the ANP/RND array photoanode with neutral electrolyte, which are respectively ascribed to the series resistance of neutral electrolyte, the fundamentally pH-dependent water oxidation mechanism on TiO2 surface, as well as the less band bending at the interface of TiO2 and neutral electrolyte...
January 4, 2018: ACS Applied Materials & Interfaces
https://www.readbyqxmd.com/read/29276505/contribution-of-raeb-a-putative-rnd-type-transporter-to-aminoglycoside-and-detergent-resistance-in-riemerella-anatipestifer
#4
Xin Zhang, Ming-Shu Wang, Ma-Feng Liu, De-Kang Zhu, Francis Biville, Ren-Yong Jia, Shun Chen, Kun-Feng Sun, Qiao Yang, Ying Wu, Xin-Xin Zhao, Xiao-Yue Chen, An-Chun Cheng
Riemerella anatipestifer is an important pathogenic bacterium that infects ducks. It exhibits resistance to multiple classes of antibiotics. Multidrug efflux pumps play a major role as a mechanism of antimicrobial resistance in Gram-negative pathogens and they are poorly understood in R. anatipestifer. In this study, a gene encoding the B739_0873 protein in R. anatipestifer CH-1, which belongs to the resistance-nodulation-cell division (RND) efflux pump family, was identified. With respect to the substrate specificity of B739_0873, the antibiotic susceptibility testing showed that the B739_0873 knockout strain was more sensitive to aminoglycosides and detergents than the wild-type strain...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/29246087/in-silico-interaction-studies-suggest-rnd-efflux-pump-mediates-polymyxin-resistance-in-acinetobacter-baumannii
#5
Privita Verma, Pramila Maurya, Monalisa Tiwari, Vishvanath Tiwari
Bacterial efflux pumps have emerged as antibiotic resistance determinants and confers multi-drug resistance to a broad range of antimicrobials as well as non-antibiotic substances. A study about translocation of antibiotic molecules through the efflux transporter, will contribute in determining substrate specificity. In the present study, we have explored RND family efflux pump extensively found in Acinetobacter baumannii i.e. AdeABC. Besides, another well studied RND efflux pump, AcrAB-TolC together with a non-RND efflux pump, NorM were investigated for comparative analysis...
December 15, 2017: Journal of Biomolecular Structure & Dynamics
https://www.readbyqxmd.com/read/29238744/energy-coupling-mechanisms-of-acrb-like-rnd-transporters
#6
Xuejun C Zhang, Min Liu, Lei Han
Prokaryotic AcrB-like proteins belong to a family of transporters of the RND superfamily, and as main contributing factor to multidrug resistance pose a tremendous threat to future human health. A unique feature of AcrB transporters is the presence of two separate domains responsible for carrying substrate and generating energy. Significant progress has been made in elucidating the three-dimensional structures of the homo-trimer complexes of AcrB-like transporters, and a three-step functional rotation was identified for this class of transporters...
2017: Biophysics Reports
https://www.readbyqxmd.com/read/29235508/genetic-adaptation-of-microbial-populations-present-in-high-intensity-catfish-production-systems-with-therapeutic-oxytetracycline-treatment
#7
Qifan Zeng, Xiangli Tian, Luxin Wang
Microbial communities that are present in aquaculture production systems play significant roles in degrading organic matter, controlling diseases, and formation of antibiotic resistance. It is important to understand the diversity and abundance of microbial communities and their genetic adaptations associated with environmental physical and chemical changes. Here we collected water and sediment samples from a high-intensity catfish production system and its original water reservoir. The metagenomic analysis showed that Proteobacteria, Actinobacteria, Bacteroidetes, Cyanobacteria, and Firmicutes were the top five phyla identified from all samples...
December 13, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29217371/reconstitution-of-the-activity-of-rnd-efflux-pumps-a-bottoms-up-approach
#8
Dhenesh Puvanendran, Quentin Cece, Martin Picard
Efflux pumps are systems devoted to the extrusion of noxious compounds. In this review, we discuss the various strategies that have thus far been undertaken for the investigation of efflux pumps after reconstitution into liposomes. It is challenging to uncover mechanisms and dynamics of efflux pumps due to a number of characteristics: their function depends on the correct assembly of three components and they span two adjacent membranes whose lipid compositions are very different. In addition, efflux pumps are active transporters that need energy to work...
December 4, 2017: Research in Microbiology
https://www.readbyqxmd.com/read/29208490/fluorescence-enlightens-rnd-pump-activity-and-the-intrabacterial-concentration-of-antibiotics
#9
Muriel Masi, Estelle Dumont, Julia Vergalli, Jelena Pajovic, Matthieu Réfrégiers, Jean-Marie Pagès
To understand antibiotic resistance in Gram-negative bacteria, a key point is to investigate antibiotic accumulation, which is defined by influx and efflux. Several methods exist to evaluate membrane permeability and efflux pump activity, but they present disadvantages and limitations. An optimized spectrofluorimetric method using intrinsic tryptophan fluorescence as an internal standard, as well as a complementary microfluorimetric assay following time-course accumulation in intact individual cells, have been developed...
December 2, 2017: Research in Microbiology
https://www.readbyqxmd.com/read/29203487/role-of-smeu1vwu2x-operon-in-the-alleviation-of-oxidative-stresses-and-the-occurrence-of-sulfamethoxazole-trimethoprim-resistant-mutants-in-stenotrophomonas-maltophilia
#10
Chao-Jung Wu, Tsu-Ting Chiu, Yi-Tsung Lin, Yi-Wei Huang, Li-Hua Li, Tsuey-Ching Yang
Overexpression of resistance-nodulation-division (RND)-type efflux pumps is an important mechanism for bacteria to combat antimicrobials. RND efflux pumps are also critical for bacterial physiology such as oxidative stress tolerance. Stenotrophomonas maltophilia, a multi-drug resistant opportunistic pathogen, harbors eight RND-type efflux pump operons. Of them, smeU1VWU2X operon is unique for its possession of two additional genes, smeU1 and smeU2, which encode proteins of short-chain dehydrogenase/reductase (SDR) family...
December 4, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/29177837/high-throughput-flow-cytometry-screening-of-multidrug-efflux-systems
#11
Mark K Haynes, Matthew Garcia, Ryan Peters, Anna Waller, Pietro Tedesco, Oleg Ursu, Cristian G Bologa, Radleigh G Santos, Clemencia Pinilla, Terry H Wu, Julie A Lovchik, Tudor I Oprea, Larry A Sklar, George P Tegos
The resistance nodulation cell division (RND) family of proteins are inner membrane transporters that associate with periplasmic adaptor proteins and outer membrane porins to affect substrate transport from the cytosol and periplasm in Gram-negative bacteria. Various structurally diverse compounds are substrates of RND transporters. Along with their notable role in antibiotic resistance, these transporters are essential for niche colonization, quorum sensing, and virulence as well as for the removal of fatty acids and bile salts...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29177832/molecular-modeling-of-multidrug-properties-of-resistance-nodulation-division-rnd-transporters
#12
Pierpaolo Cacciotto, Venkata K Ramaswamy, Giuliano Malloci, Paolo Ruggerone, Attilio V Vargiu
Efflux pumps of the resistance nodulation division (RND) superfamily are among the major contributors to intrinsic and acquired multidrug resistance in Gram-negative bacteria. Structural information on AcrAB-TolC and MexAB-OprM, major efflux pumps of Escherichia coli and Pseudomonas aeruginosa respectively, boosted intensive research aimed at understanding the molecular mechanisms ruling the active extrusion processes. In particular, several studies were devoted to the understanding of the determinants behind the extraordinary broad specificity of the RND transporters AcrB and MexB...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29177830/covalently-linked-trimers-of-rnd-resistance-nodulation-division-efflux-transporters-to-study-their-mechanism-of-action-escherichia-coli-acrb-multidrug-exporter-as-an-example
#13
Hiroshi Nikaido
Transporters undergo large conformational changes in their functional cycle. RND (Resistance-Nodulation-Division) family efflux transporters usually exist as homotrimers, and each protomer was proposed to undergo a cycle of conformational changes in succession so that at any given time the trimer would contain three protomers of different conformations, the functionally rotating mechanism of transport. This mechanism implies that the inactivation of one protomer among three will inactivate the entire trimeric ensemble by blocking the functional rotation...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29177829/biochemical-reconstitution-and-characterization-of-multicomponent-drug-efflux-transporters
#14
Martin Picard, Elena B Tikhonova, Isabelle Broutin, Shuo Lu, Alice Verchère, Helen I Zgurskaya
Efflux pumps are the major determinants in bacterial multidrug resistance. In Gram-negative bacteria, efflux transporters are organized as macromolecular tripartite machineries that span the two-membrane cell envelope of the bacterium. Biochemical data on purified proteins are essential to draw a mechanistic picture of this highly dynamical, multicomponent, efflux system. We describe protocols for the reconstitution and the in vitro study of transporters belonging to RND and ABC superfamilies: the AcrAB-TolC and MacAB-TolC efflux systems from Escherichia coli and the MexAB-OprM efflux pump from Pseudomonas aeruginosa...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29177825/crystallographic-analysis-of-the-cusba-heavy-metal-efflux-complex-of-escherichia-coli
#15
Jared A Delmar, Edward W Yu
Crystallization is one of the most successful techniques used to determine protein structure, especially for membrane proteins. However, the application of this technique is not straightforward and often hampered by the difficulties associated with expression, purification, and crystallization. Here we present our protocol and methodology for crystallizing the CusBA adaptor-transporter complex of Escherichia coli. Using these procedures, we were able to produce the first co-crystal structure of a resistance-nodulation-cell division (RND) transporter in complex with its associated membrane fusion protein...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29177823/crystallographic-analysis-of-drug-and-inhibitor-binding-structure-of-rnd-type-multidrug-exporter-acrb-in-physiologically-relevant-asymmetric-crystals
#16
Ryosuke Nakashima, Keisuke Sakurai, Akihito Yamaguchi
Xenobiotic extruding pumps have recently been known to be widely distributed in living organisms from mammalian to bacteria as a host-defense mechanism in cellular level. These pumps not only confer multidrug resistance of cancer cells and pathogenic bacteria but also cause hereditary diseases through the mutation. Our purposes are to elucidate the molecular structures and mechanisms of these xenobiotic exporters.We had succeeded to determine the crystal structure of bacterial major multidrug exporter AcrB at 3...
2018: Methods in Molecular Biology
https://www.readbyqxmd.com/read/29146106/the-hydrophobic-trap-the-achilles-heel-of-rnd-efflux-pumps
#17
Zachary Aron, Timothy J Opperman
Resistance-nodulation-division (RND) superfamily efflux pumps play a major role in multidrug resistance (MDR) of Gram-negative pathogens by extruding diverse classes of antibiotics from the cell. There has been considerable interest in developing efflux pump inhibitors (EPIs) of RND pumps as adjunctive therapies. The primary challenge in EPI discovery has been the highly hydrophobic, poly-specific substrate binding site of the target. Recent findings have identified the hydrophobic trap, a narrow phenylalanine-lined groove in the substrate-binding site, as the "Achilles heel" of the RND efflux pumps...
November 13, 2017: Research in Microbiology
https://www.readbyqxmd.com/read/29133936/the-rho-gtpase-signalling-pathway-in-urothelial-carcinoma
#18
REVIEW
Solomon L Woldu, Ryan C Hutchinson, Laura-Maria Krabbe, Oner Sanli, Vitaly Margulis
Urothelial carcinoma remains a clinical challenge: non-muscle-invasive disease has a high rate of recurrence and risk of progression, and outcomes for patients with advanced disease are poor, owing to a lack of effective systemic therapies. The Rho GTPase family of enzymes was first identified >30 years ago and contains >20 members, which are divided into eight subfamilies: Cdc42, Rac, Rho, RhoUV, RhoBTB, RhoDF, RhoH, and Rnd. Rho GTPases are molecular on-off switches, which are increasingly being understood to have a critical role in a number of cellular processes, including cell migration, cell polarity, cell adhesion, cell cycle progression, and regulation of the cytoskeleton...
November 14, 2017: Nature Reviews. Urology
https://www.readbyqxmd.com/read/29128951/insights-from-the-genomes-of-microbes-thriving-in-uranium-enriched-sediments
#19
Brodie Sutcliffe, Anthony A Chariton, Andrew J Harford, Grant C Hose, Sarah Stephenson, Paul Greenfield, David J Midgley, Ian T Paulsen
Elevated uranium dose (4 g kg(-1)) causes a shift in billabong sediment communities that result in the enrichment of five bacterial species. These taxa include Geobacter, Geothrix and Dyella species, as well as a novel-potentially predatory-Bacteroidetes species, and a new member of class Anaerolineae (Chloroflexi). Additionally, a population of methanogenic Methanocella species was also identified. Genomic reconstruction and metabolic examination of these taxa reveal a host of divergent life strategies and putative niche partitioning...
November 11, 2017: Microbial Ecology
https://www.readbyqxmd.com/read/29128373/regulation-of-the-acrab-tolc-efflux-pump-in-enterobacteriaceae
#20
Natasha Weston, Prateek Sharma, Vito Ricci, Laura J V Piddock
Bacterial multidrug efflux systems are a major mechanism of antimicrobial resistance and are fundamental to the physiology of Gram-negative bacteria. The resistance-nodulation-division (RND) family of efflux pumps is the most clinically significant, as it is associated with multidrug resistance. Expression of efflux systems is subject to multiple levels of regulation, involving local and global transcriptional regulation as well as post-transcriptional and post-translational regulation. The best-characterised RND system is AcrAB-TolC, which is present in Enterobacteriaceae...
November 8, 2017: Research in Microbiology
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