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https://www.readbyqxmd.com/read/28717043/tandem-amplification-of-sccmec-can-drive-high-level-methicillin-resistance-in-mrsa
#1
Laura A Gallagher, Simone Coughlan, Nikki S Black, Pierce Lalor, Elaine M Waters, Bryan Wee, Mick Watson, Tim Downing, J Ross Fitzgerald, Gerard T A Fleming, James P O'Gara
Hospital-associated methicillin-resistant Staphylococcus aureus strains typically express high level, homogenous (HoR) β-lactam resistance, whereas community-associated MRSA (CA-MRSA) more commonly express low level heterogeneous (HeR) resistance. Expression of the HoR phenotype typically requires both increased expression of the mecA gene, carried on the Staphylococcus cassette chromosome SCCmec element, and additional mutational event(s) elsewhere on the chromosome. Here the oxacillin concentration in a chemostat culture of the CA-MRSA strain USA300 was increased from 8 μg/ml to 130 μg/ml over 13 days to isolate highly oxacillin resistant derivatives...
July 17, 2017: Antimicrobial Agents and Chemotherapy
https://www.readbyqxmd.com/read/28659890/pre-cultivation-with-selected-prebiotics-enhances-the-survival-and-the-stress-response-of-lactobacillus-rhamnosus-strains-in-simulated-gastrointestinal-transit
#2
Mariantonietta Succi, Patrizio Tremonte, Gianfranco Pannella, Luca Tipaldi, Autilia Cozzolino, Rossana Romaniello, Elena Sorrentino, Raffaele Coppola
In our study, we dwelled upon combinations of lactobacilli/prebiotics, considering four different strains belonging to the Lactobacillus rhamnosus species, including Lactobacillus rhamnosus GG (LGG), and different prebiotics often found in commercial synbiotic products, such as inulin, lactulose and polyols mannitol and sorbitol. In the first step of the research, the survival, the growth kinetic parameters and the protein expression of Lb. rhamnosus strains cultivated in presence of the different prebiotics as a unique carbon source were evaluated...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28536693/the-essential-role-of-clpxp-in-caulobacter-crescentus-requires-species-constrained-substrate-specificity
#3
Robert H Vass, Jacob Nascembeni, Peter Chien
The ClpXP protease is a highly conserved AAA+ degradation machine that is present throughout bacteria and in eukaryotic organelles. ClpXP is essential in some bacteria, such as Caulobacter crescentus, but dispensible in others, such as Escherichia coli. In Caulobacter, ClpXP normally degrades the SocB toxin and increased levels of SocB result in cell death. ClpX can be deleted in cells lacking this toxin, but these ΔclpX strains are still profoundly deficient in morphology and growth supporting the existence of additional important functions for ClpXP...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28523271/the-protein-chaperone-clpx-targets-native-and-non-native-aggregated-substrates-for-remodeling-disassembly-and-degradation-with-clpp
#4
Christopher J LaBreck, Shannon May, Marissa G Viola, Joseph Conti, Jodi L Camberg
ClpX is a member of the Clp/Hsp100 family of ATP-dependent chaperones and partners with ClpP, a compartmentalized protease, to degrade protein substrates bearing specific recognition signals. ClpX targets specific proteins for degradation directly or with substrate-specific adaptor proteins. Native substrates of ClpXP include proteins that form large oligomeric assemblies, such as MuA, FtsZ, and Dps in Escherichia coli. To remodel large oligomeric substrates, ClpX utilizes multivalent targeting strategies and discriminates between assembled and unassembled substrate conformations...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28490437/high-throughput-crispri-phenotyping-identifies-new-essential-genes-in-streptococcus-pneumoniae
#5
Xue Liu, Clement Gallay, Morten Kjos, Arnau Domenech, Jelle Slager, Sebastiaan P van Kessel, Kèvin Knoops, Robin A Sorg, Jing-Ren Zhang, Jan-Willem Veening
Genome-wide screens have discovered a large set of essential genes in the opportunistic human pathogen Streptococcus pneumoniae However, the functions of many essential genes are still unknown, hampering vaccine development and drug discovery. Based on results from transposon sequencing (Tn-seq), we refined the list of essential genes in S. pneumoniae serotype 2 strain D39. Next, we created a knockdown library targeting 348 potentially essential genes by CRISPR interference (CRISPRi) and show a growth phenotype for 254 of them (73%)...
May 10, 2017: Molecular Systems Biology
https://www.readbyqxmd.com/read/28467184/multilocus-genetic-characterization-of-lactobacillus-fermentum-isolated-from-ready-to-eat-canned-food
#6
Irshad M Sulaiman, Emily Jacobs, Steven Simpson, Khalil Kerdahi
The primary mission of the U.S. Food and Drug Administration is to enforce the Food, Drug, and Cosmetic Act and regulate food, drug, and cosmetic products. Thus, this agency monitors the presence of pathogenic microorganisms in these products, including canned foods, as one of the regulatory action criteria and also ensures that these products are safe for human consumption. This study was carried out to investigate the effectiveness of pathogen control and integrity of ready-to-eat canned food containing Black Bean Corn Poblano Salsa...
June 2017: Journal of Food Protection
https://www.readbyqxmd.com/read/28451288/insights-into-clpxp-proteolysis-heterooligomerization-and-partial-deactivation-enhance-chaperone-affinity-and-substrate-turnover-in-listeria-monocytogenes
#7
Dóra Balogh, Maria Dahmen, Matthias Stahl, Marcin Poreba, Malte Gersch, Marcin Drag, Stephan A Sieber
Caseinolytic proteases (ClpP) are important for recognition and controlled degradation of damaged proteins. While the majority of bacterial organisms utilize only a single ClpP, Listeria monocytogenes expresses two isoforms (LmClpP1 and LmClpP2). LmClpPs assemble into either a LmClpP2 homocomplex or a LmClpP1/2 heterooligomeric complex. The heterocomplex in association with the chaperone ClpX, exhibits a boost in proteolytic activity for unknown reasons. Here, we use a combined chemical and biochemical strategy to unravel two activation principles of LmClpPs...
February 1, 2017: Chemical Science
https://www.readbyqxmd.com/read/28421184/the-proteasomal-atpases-use-a-slow-but-highly-processive-strategy-to-unfold-proteins
#8
Aaron Snoberger, Raymond T Anderson, David M Smith
All domains of life have ATP-dependent compartmentalized proteases that sequester their peptidase sites on their interior. ATPase complexes will often associate with these compartmentalized proteases in order to unfold and inject substrates into the protease for degradation. Significant effort has been put into understanding how ATP hydrolysis is used to apply force to proteins and cause them to unfold. The unfolding kinetics of the bacterial ATPase, ClpX, have been shown to resemble a fast motor that traps unfolded intermediates as a strategy to unfold proteins...
2017: Frontiers in Molecular Biosciences
https://www.readbyqxmd.com/read/28186774/quantitative-map-of-%C3%AE-lactone-induced-virulence-regulation
#9
Joanna Krysiak, Matthias Stahl, Jan Vomacka, Christian Fetzer, Markus Lakemeyer, Anja Fux, Stephan A Sieber
β-Lactones have recently been introduced as the first selective ClpP inhibitors that attenuate virulence of both sensitive Staphylococcus aureus and multiresistant strains (MRSA). Although previous knockout studies showed that ClpP is essential for S. aureus alpha-toxin production, a link between β-lactone inhibition and molecular virulence mechanisms has been lacking so far. We here perform a chemical-proteomic approach to elucidate antivirulence pathways. First, we demonstrate by gel-free activity-based protein profiling that ClpP is the predominant target of β-lactones...
February 10, 2017: Journal of Proteome Research
https://www.readbyqxmd.com/read/28114338/proteolysis-dependent-remodeling-of-the-tubulin-homolog-ftsz-at-the-division-septum-in-escherichia-coli
#10
Marissa G Viola, Christopher J LaBreck, Joseph Conti, Jodi L Camberg
During bacterial cell division a dynamic protein structure called the Z-ring assembles at the septum. The major protein in the Z-ring in Escherichia coli is FtsZ, a tubulin homolog that polymerizes with GTP. FtsZ is degraded by the two-component ATP-dependent protease ClpXP. Two regions of FtsZ, located outside of the polymerization domain in the unstructured linker and at the C-terminus, are important for specific recognition and degradation by ClpXP. We engineered a synthetic substrate containing green fluorescent protein (Gfp) fused to an extended FtsZ C-terminal tail (residues 317-383), including the unstructured linker and the C-terminal conserved region, but not the polymerization domain, and showed that it is sufficient to target a non-native substrate for degradation in vitro...
2017: PloS One
https://www.readbyqxmd.com/read/28112428/specific-glutamic-acid-residues-in-targeted-proteins-induce-exaggerated-retardations-in-phos-tag-sds-page-migration
#11
Eiji Kinoshita, Emiko Kinoshita-Kikuta, Kiyonobu Karata, Toshiki Kawano, Atsuhiro Nishiyama, Morihisa Yamato, Tohru Koike
We describe two unique proteins, Escherichia coli ClpX and human histone H2A, that show extremely retarded migrations relative to their molecular weights in Phos-tag SDS-PAGE, despite being nonphosphorylated. Although ClpX separated into multiple migration bands in Phos-tag gels, the separation was not due to phosphorylation. The N-terminal 47-61 region of ClpX was responsible for producing multiple phosphorylation-independent structural variants, even under denaturing conditions, and some of these variants were detected as highly up-shifted bands...
April 2017: Electrophoresis
https://www.readbyqxmd.com/read/28039103/itraq-based-proteome-analysis-of-fluoroquinolone-resistant-staphylococcus-aureus
#12
Van Chi Thai, Teck Kwang Lim, Kim Phuong Uyen Le, Qingsong Lin, Thi Thu Hoai Nguyen
OBJECTIVES: The aim of this study was to compare global protein expression changes during fluoroquinolone (FQ) exposure of Staphylococcus aureus. METHODS: Total protein extracts of wild-type S. aureus ATCC 29213 and six multidrug-resistant (MDR) strains derived from the wild-type under different FQ exposures were analysed using the 8-plex isobaric tag for relative and absolute quantitation (iTRAQ) method combined with LC-MS/MS analysis. Differentially expressed proteins were searched for their Gene Ontology (GO) annotation (UniProt database) and protein-protein interaction network (STRING v...
December 27, 2016: Journal of Global Antimicrobial Resistance
https://www.readbyqxmd.com/read/27981232/strain-dependent-recognition-of-a-unique-degradation-motif-by-clpxp-in-streptococcus-mutans
#13
Biswanath Jana, Liang Tao, Indranil Biswas
Streptococcus mutans, a dental pathogen, has a remarkable ability to cope with environmental stresses. Under stress conditions, cytoplasmic proteases play a major role in controlling the stability of regulatory proteins and preventing accumulation of damaged and misfolded proteins. ClpXP, a well-conserved cytoplasmic proteolytic system, is crucial in maintaining cellular homeostasis in bacteria. ClpX is primarily responsible for recognition of substrates and subsequent translocation of unfolded substrates into the ClpP proteolytic compartment for degradation...
November 2016: MSphere
https://www.readbyqxmd.com/read/27978916/-analysis-of-virulence-factors-of-porphyromonas-endodontalis-based-on-comparative-proteomics-technique
#14
H Li, H Ji, S S Wu, B X Hou
Objective: To analyze the protein expression profile and the potential virulence factors of Porphyromonas endodontalis (Pe) via comparison with that of two strains of Porphyromonas gingivalis (Pg) with high and low virulences, respectively. Methods: Whole cell comparative proteomics of Pe ATCC35406 was examined and compared with that of high virulent strain Pg W83 andlow virulent strain Pg ATCC33277, respectively. Isobaric tags for relative and absolute quantitation (iTRAQ) combined with nano liquid chromatography-tandem mass spectrometry (Nano-LC-MS/MS) were adopted to identify and quantitate the proteins of Pe and two strains of Pg with various virulences by using the methods of isotopically labeled peptides, mass spectrometric detection and bioinformatics analysis...
December 9, 2016: Zhonghua Kou Qiang Yi Xue za Zhi, Zhonghua Kouqiang Yixue Zazhi, Chinese Journal of Stomatology
https://www.readbyqxmd.com/read/27849175/two-isoforms-of-clp-peptidase-in-pseudomonas-aeruginosa-control-distinct-aspects-of-cellular-physiology
#15
Branwen M Hall, Elena B M Breidenstein, César de la Fuente-Núñez, Fany Reffuveille, Gina D Mawla, Robert E W Hancock, Tania A Baker
Caseinolytic peptidases (ClpPs) regulate diverse aspects of cellular physiology in bacteria. Some species have multiple ClpPs including opportunistic pathogen Pseudomonas aeruginosa in which there is an archetypical isoform, ClpP1, and a second isoform, ClpP2, about which little is known. Here we use phenotypic assays to investigate biological roles of ClpP1 and ClpP2 and biochemical assays to characterize purified ClpP1, ClpP2, ClpX and ClpA. Interestingly ClpP1 and ClpP2 have distinct intracellular roles for motility, pigment production, iron scavenging and biofilm formation...
November 14, 2016: Journal of Bacteriology
https://www.readbyqxmd.com/read/27669037/substrate-translocating-loops-regulate-mechanochemical-coupling-and-power-production-in-aaa-protease-clpxp
#16
Piere Rodriguez-Aliaga, Luis Ramirez, Frank Kim, Carlos Bustamante, Andreas Martin
ATP-dependent proteases of the AAA+ family, including Escherichia coli ClpXP and the eukaryotic proteasome, contribute to maintenance of cellular proteostasis. ClpXP unfolds and translocates substrates into an internal degradation chamber, using cycles of alternating dwell and burst phases. The ClpX motor performs chemical transformations during the dwell and translocates the substrate in increments of 1-4 nm during the burst, but the processes occurring during these phases remain unknown. Here we characterized the complete mechanochemical cycle of ClpXP, showing that ADP release and ATP binding occur nonsequentially during the dwell, whereas ATP hydrolysis and phosphate release occur during the burst...
November 2016: Nature Structural & Molecular Biology
https://www.readbyqxmd.com/read/27558626/borrelia-mayonii-sp-nov-a-member-of-the-borrelia-burgdorferi-sensu-lato-complex-detected-in-patients-and-ticks-in-the-upper-midwestern-united-states
#17
Bobbi S Pritt, Laurel B Respicio-Kingry, Lynne M Sloan, Martin E Schriefer, Adam J Replogle, Jenna Bjork, Gongping Liu, Luke C Kingry, Paul S Mead, David F Neitzel, Elizabeth Schiffman, Diep K Hoang Johnson, Jeffrey P Davis, Susan M Paskewitz, David Boxrud, Alecia Deedon, Xia Lee, Tracy K Miller, Michelle A Feist, Christopher R Steward, Elitza S Theel, Robin Patel, Cole L Irish, Jeannine M Petersen
Lyme borreliosis (LB) is a multisystem disease caused by spirochetes in the Borrelia burgdorferisensu lato (Bbsl) genospecies complex. We previously described a novel Bbsl genospecies (type strain MN14-1420T) that causes LB among patients with exposures to ticks in the upper midwestern USA. Patients infected with the novel Bbsl genospecies demonstrated higher levels of spirochetemia and somewhat differing clinical symptoms as compared with those infected with other Bbsl genospecies. The organism was detected from human specimens using PCR, microscopy, serology and culture...
November 2016: International Journal of Systematic and Evolutionary Microbiology
https://www.readbyqxmd.com/read/27507828/the-cell-wall-polymer-lipoteichoic-acid-becomes-nonessential-in-staphylococcus-aureus-cells-lacking-the-clpx-chaperone
#18
Kristoffer T Bæk, Lisa Bowman, Charlotte Millership, Mia Dupont Søgaard, Volkhard Kaever, Pia Siljamäki, Kirsi Savijoki, Pekka Varmanen, Tuula A Nyman, Angelika Gründling, Dorte Frees
UNLABELLED: Lipoteichoic acid (LTA) is an important cell wall component of Gram-positive bacteria and a promising target for the development of vaccines and antimicrobial compounds against Staphylococcus aureus Here we demonstrate that mutations in the conditionally essential ltaS (LTA synthase) gene arise spontaneously in an S. aureus mutant lacking the ClpX chaperone. A wide variety of ltaS mutations were selected, and among these, a substantial portion resulted in premature stop codons and other changes predicted to abolish LtaS synthesis...
August 9, 2016: MBio
https://www.readbyqxmd.com/read/27496948/novel-mechanisms-for-heme-dependent-degradation-of-alas1-protein-as-a-component-of-negative-feedback-regulation-of-heme-biosynthesis
#19
Yoshiko Kubota, Kazumi Nomura, Yasutake Katoh, Rina Yamashita, Kiriko Kaneko, Kazumichi Furuyama
In eukaryotic cells, heme production is tightly controlled by heme itself through negative feedback-mediated regulation of nonspecific 5-aminolevulinate synthase (ALAS1), which is a rate-limiting enzyme for heme biosynthesis. However, the mechanism driving the heme-dependent degradation of the ALAS1 protein in mitochondria is largely unknown. In the current study, we provide evidence that the mitochondrial ATP-dependent protease ClpXP, which is a heteromultimer of CLPX and CLPP, is involved in the heme-dependent degradation of ALAS1 in mitochondria...
September 23, 2016: Journal of Biological Chemistry
https://www.readbyqxmd.com/read/27389535/the-mitochondrial-unfoldase-peptidase-complex-clpxp-controls-bioenergetics-stress-and-metastasis
#20
Jae Ho Seo, Dayana B Rivadeneira, M Cecilia Caino, Young Chan Chae, David W Speicher, Hsin-Yao Tang, Valentina Vaira, Silvano Bosari, Alessandro Palleschi, Paolo Rampini, Andrew V Kossenkov, Lucia R Languino, Dario C Altieri
Mitochondria must buffer the risk of proteotoxic stress to preserve bioenergetics, but the role of these mechanisms in disease is poorly understood. Using a proteomics screen, we now show that the mitochondrial unfoldase-peptidase complex ClpXP associates with the oncoprotein survivin and the respiratory chain Complex II subunit succinate dehydrogenase B (SDHB) in mitochondria of tumor cells. Knockdown of ClpXP subunits ClpP or ClpX induces the accumulation of misfolded SDHB, impairing oxidative phosphorylation and ATP production while activating "stress" signals of 5' adenosine monophosphate-activated protein kinase (AMPK) phosphorylation and autophagy...
July 2016: PLoS Biology
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