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Kelei Zhao, Xikun Zhou, Wujiao Li, Xiuyue Zhang, Bisong Yue
Bacteria use a cell-cell communication system termed quorum-sensing (QS) to adjust population size by coordinating the costly but beneficial cooperative behaviors. It has long been suggested that bacterial social conflict for expensive extracellular products may drive QS divergence and cause the "tragedy of the commons". However, the underlying molecular mechanism of social divergence and its evolutionary consequences for the bacterial ecology still remain largely unknown. By using the model bacterium Pseudomonas aeruginosa PAO1, here we show that nutrient reduction can promote QS divergence for population fitness during evolution but requiring adequate cell density...
October 7, 2016: Scientific Reports
John B Feltner, Daniel J Wolter, Christopher E Pope, Marie-Christine Groleau, Nicole E Smalley, E Peter Greenberg, Nicole Mayer-Hamblett, Jane Burns, Eric Déziel, Lucas R Hoffman, Ajai A Dandekar
: Chronic Pseudomonas aeruginosa infections cause significant morbidity in patients with cystic fibrosis (CF). Over years to decades, P. aeruginosa adapts genetically as it establishes chronic lung infections. Nonsynonymous mutations in lasR, the quorum-sensing (QS) master regulator, are common in CF. In laboratory strains of P. aeruginosa, LasR activates transcription of dozens of genes, including that for another QS regulator, RhlR. Despite the frequency with which lasR coding variants have been reported to occur in P...
October 4, 2016: MBio
Damien Maura, Ronen Hazan, Tomoe Kitao, Alicia E Ballok, Laurence G Rahme
Pseudomonas aeruginosa defies eradication by antibiotics and is responsible for acute and chronic human infections due to a wide variety of virulence factors. Currently, it is believed that MvfR (PqsR) controls the expression of many of these factors indirectly via the pqs and phnAB operons. Here we provide strong evidence that MvfR may also bind and directly regulate the expression of additional 35 loci across the P. aeruginosa genome, including major regulators and virulence factors, such as the quorum sensing (QS) regulators lasR and rhlR, and genes involved in protein secretion, translation, and response to oxidative stress...
September 28, 2016: Scientific Reports
Chao Wang, John R McPherson, Lian-Hui Zhang, Steve Rozen, Kanaga Sabapathy
Pseudomonas aeruginosa is an opportunistic pathogen which infects cystic fibrosis and cancer patients with compromised immune systems. LasR is a master regulator which controls the virulence of P. aeruginosa in response to bacterial cell-density and host signals. During infection, lasR is frequently mutated, conferring P. aeruginosa a growth advantage in hosts and enhances resistance to widely used antibiotics. However, the mechanistic basis of lasR mutation is not well understood. We have tested here the hypothesis that transcription strength is a contributory determinant of lasR mutagenesis...
October 2016: DNA Repair
John H Hammond, Wesley P Hebert, Amanda Naimie, Kathryn Ray, Rachel D Van Gelder, Antonio DiGiandomenico, Prajna Lalitha, Muthiah Srinivasan, Nisha R Acharya, Thomas Lietman, Deborah A Hogan, Michael E Zegans
The Steroids for Corneal Ulcers Trial (SCUT) was a multicenter, international study of bacterial keratitis in which 101 Pseudomonas aeruginosa infections were treated. Twenty-two of 101 P. aeruginosa isolates collected had a colony morphology characteristic of a loss-of-function mutation in lasR, the gene encoding a quorum-sensing master regulator. Ulcers caused by these 22 strains were associated with larger areas of corneal opacification, worse vision, and a lower rate of vision recovery in response to treatment than ulcers caused by the other isolates...
September 2016: MSphere
Önder Kimyon, Zehra I Ulutürk, Shashidhar Nizalapur, Matthew Lee, Samuel K Kutty, Sabrina Beckmann, Naresh Kumar, Mike Manefield
N-acetyl glucosamine, the monomer of chitin, is an abundant source of carbon and nitrogen in nature as it is the main component and breakdown product of many structural polymers. Some bacteria use N-acyl-L-homoserine lactone (AHL) mediated quorum sensing (QS) to regulate chitinase production in order to catalyze the cleavage of chitin polymers into water soluble N-acetyl-D-glucosamine (NAG) monomers. In this study, the impact of NAG on QS activities of LuxR, LasR, and CviR regulated gene expression was investigated by examining the effect of NAG on QS regulated green fluorescent protein (GFP), violacein and extracellular chitinase expression...
2016: Frontiers in Microbiology
Vimal B Maisuria, Yossef Lopez-de Los Santos, Nathalie Tufenkji, Eric Déziel
Bacteria have evolved multiple strategies for causing infections that include producing virulence factors, undertaking motility, developing biofilms, and invading host cells. N-acylhomoserine lactone (AHL)-mediated quorum sensing (QS) tightly regulates the expression of multiple virulence factors in the opportunistic pathogenic bacterium Pseudomonas aeruginosa. Thus, inhibiting QS could lead to health benefits. In this study, we demonstrate an anti-virulence activity of a cranberry extract rich in proanthocyanidins (cerPAC) against P...
2016: Scientific Reports
Soha El-Shaer, Mona Shaaban, Rasha Barwa, Ramadan Hassan
The spread of multiple drug resistance Pseudomonas aeruginosa isolates constitutes a serious clinical challenge. Bacterial efflux machinery is a crucial mechanism of resistance among P. aeruginosa. Efflux inhibitors such as phenylalanine arginyl -naphthylamide (PAN) promote the bacterial susceptibility to antimicrobial agents. The pathogenesis of P. aeruginosa is co-ordinated via quorum sensing (QS). This study aims to find out the impact of efflux pump inhibitor, PAN, on QS and virulence attributes in clinical isolates of P...
August 5, 2016: Journal of Medical Microbiology
Lucy D Burr, Geraint B Rogers, Alice C-H Chen, Brett R Hamilton, Gertruida F Pool, Steven L Taylor, Deon Venter, Simon D Bowler, Sally Biga, Michael A McGuckin
RATIONALE: The mechanism by which low-dose macrolide therapy reduces exacerbations in non-cystic fibrosis bronchiectasis is not known. Pseudomonas aeruginosa quorum sensing controls the expression of a range of pathogenicity traits and is inhibited by macrolide in vitro. Quorum sensing inhibition renders P. aeruginosa less pathogenic, potentially reducing its contribution to airway damage. OBJECTIVES: The aim of this study was to determine whether long-term low-dose erythromycin inhibits P...
October 2016: Annals of the American Thoracic Society
Shuang Sun, Lian Zhou, Kaiming Jin, Haixia Jiang, Ya-Wen He
Pseudomonas aeruginosa strain PA1201 is a newly identified rhizobacterium that produces high levels of the secondary metabolite phenazine-1-carboxylic acid (PCA), the newly registered biopesticide Shenqinmycin. PCA production in liquid batch cultures utilizing a specialized PCA-promoting medium (PPM) typically occurs after the period of most rapid growth, and production is regulated in a quorum sensing (QS)-dependent manner. PA1201 contains two PCA biosynthetic gene clusters phz1 and phz2; both clusters contribute to PCA production, with phz2 making a greater contribution...
2016: Scientific Reports
Ramadan Hassan, Mona I Shaaban, Fatma M Abdel Bar, Areej M El-Mahdy, Shadi Shokralla
Quorum sensing (QS) systems communicate bacterial population and stimulate microbial pathogenesis through signaling molecules. Inhibition of QS signals potentially suppresses microbial infections. Antimicrobial properties of Streptomyces have been extensively studied, however, less is known about quorum sensing inhibitory (QSI) activities of Streptomyces. This study explored the QSI potential of Streptomyces isolated from soil. Sixty-five bacterial isolates were purified from soil samples with morphological characteristics of Streptomyces...
2016: Frontiers in Microbiology
Satyanarayana Swamy Vyshnava, Dileep Kumar Kanderi, Shiva Prasad Panjala, Kamesh Pandian, Rajasekhar Reddy Bontha, Praveen Kumar Reddy Goukanapalle, Babajan Banaganapalli
Studies were undertaken to examine the mechanism of mediation of silver nanoparticles in inhibiting biofilm formation by Pseudomonas aeruginosa through LuxI/LuxR system of signal transduction. This study includes the basic signaling transduction mechanism LasR, QscR, RhlR, and Vfr signaling model systems. The arbitrary homology models built with the I-TASSER server were evaluated and validated with the Qmean web server. Based on the Z-score and the relative square mean distance (RMSD) values, the structures were validated...
May 21, 2016: Applied Biochemistry and Biotechnology
Manon Ruffin, Claudia Bilodeau, Émilie Maillé, Shantelle L LaFayette, Geoffrey A McKay, Nguyen Thu Ngan Trinh, Trevor Beaudoin, Martin-Yvon Desrosiers, Simon Rousseau, Dao Nguyen, Emmanuelle Brochiero
Chronic Pseudomonas aeruginosa lung infections are associated with progressive epithelial damage and lung function decline. In addition to its role in tissue injury, the persistent presence of P. aeruginosa-secreted products may also affect epithelial repair ability, raising the need for new antivirulence therapies. The purpose of our study was to better understand the outcomes of P. aeruginosa exoproducts exposure on airway epithelial repair processes to identify a strategy to counteract their deleterious effect...
September 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Venkadesaperumal Gopu, Prathapkumar Halady Shetty
Quorum sensing (QS) is the process of population dependent cell to cell communication used by bacteria to regulate their phenotypic characteristics. Key virulence factors that determine the bacterial pathogenicity and food spoilage were found to be regulated by QS mechanism. Hence, disrupting the QS signaling pathway could be an attractive strategy to manage food borne pathogens. In the current study, QS inhibitory activity of a naturally occurring anthocyanin-cyanidin and its anti-biofilm property were assessed against an opportunistic pathogen Klebsiella pneumoniae, using a bio-sensor strain...
February 2016: Journal of Food Science and Technology
Andrey Damianov, Yi Ying, Chia-Ho Lin, Ji-Ann Lee, Diana Tran, Ajay A Vashisht, Emad Bahrami-Samani, Yi Xing, Kelsey C Martin, James A Wohlschlegel, Douglas L Black
Rbfox proteins control alternative splicing and posttranscriptional regulation in mammalian brain and are implicated in neurological disease. These proteins recognize the RNA sequence (U)GCAUG, but their structures and diverse roles imply a variety of protein-protein interactions. We find that nuclear Rbfox proteins are bound within a large assembly of splicing regulators (LASR), a multimeric complex containing the proteins hnRNP M, hnRNP H, hnRNP C, Matrin3, NF110/NFAR-2, NF45, and DDX5, all approximately equimolar to Rbfox...
April 21, 2016: Cell
Lei Feng, Qingqing Xiang, Qing Ai, Zhengli Wang, Yunhui Zhang, Qi Lu
BACKGROUND: Quorum sensing (QS) systems play an important role in modulating biofilm formation. Recent studies have found that the QS molecules had complex effects on the host immune systems. In addition, regulatory T cells (Tregs), known as important negative regulators in the immune system, have been found upregulated in multiple chronic infections. Therefore, the QS systems were hypothesized to be involved in modulating Tregs in biofilm-associated infections. Object. To explore the effects of QS systems on Tregs in catheter-related Pseudomonas aeruginosa biofilm infection rat models...
2016: Mediators of Inflammation
Ghazaleh Rostaminia, Jennifer D Peck, Kim Van Delft, Ranee Thakar, Abdul Sultan, S Abbas Shobeiri
OBJECTIVES: The aim of this study was to establish the predictive role of obstetric variables for obstetric outcomes and birth related levator ani muscle (LAM) trauma. METHODS: In this prospective study, women underwent 3-dimensional pelvic floor ultrasound at their first appointment at 36 weeks and also 3 months postpartum. The measurements included minimal levator hiatus circumference (MLHC) and the ratio of fetal head circumference to MLHC = head-induced stretch ratio (HISR) as an indicator of the discrepancy between passage and passing canal...
September 2016: Female Pelvic Medicine & Reconstructive Surgery
Prapti Kafle, Amanda N Amoh, Jocelyn M Reaves, Emma G Suneby, Kathryn A Tutunjian, Reed L Tyson, Tanya L Schneider
The LasR regulator protein functions at the top of the Pseudomonas aeruginosa quorum-sensing hierarchy and is implicated in promoting bacterial virulence. Of note is recent evidence that this transcription factor may also respond to oxidative stress. Here, all cysteines in LasR were inspected to deduce their redox sensitivity and to probe the connection between stress response and LasR activity using purified LasR and individual LasR domains. Cys(79) in the ligand binding domain of LasR appears to be important for ligand recognition and folding of this domain to potentiate DNA binding but does not seem to be sensitive to oxidative stress when bound to its native ligand...
May 27, 2016: Journal of Biological Chemistry
Benedict Wu, Joseph Capilato, Michelle P Pham, Jean Walker, Bernd Spur, Ana Rodriguez, Lark J Perez, Kingsley Yin
Bacterial infections can quickly turn into sepsis, with its attendant clinical sequelae of inflammation, tissue injury, and organ failure. Paradoxically, sustained inflammation in sepsis may lead to immune suppression, because of which the host is unable to clear the existing infection. Use of agents that suppress the inflammatory response may accelerate host immune suppression, whereas use of traditional antibiotics does not significantly affect inflammation. In this study, we investigated whether lipoxin A4 (LXA4), a specialized, proresolution lipid mediator, could increase neutrophil phagocytic activity as well as reduce bacterial virulence...
June 2016: FASEB Journal: Official Publication of the Federation of American Societies for Experimental Biology
Wenyuan Li, Bo Guan, Xinxin Zhang, Jianhua Yan, Yue Zhou, Xingbo Liu
Ruddlesden-Popper (R-P) phase materials have been investigated widely as cathode candidates for IT-SOFCs. However, widespread application of R-P phase cathodes demands further improvement in electrode activity whose progress is hindered by the limited information in the oxygen reduction reaction (ORR). The ORR mechanism for the R-P phase is therefore investigated in this paper using (LaSr)2NiO(4±δ) as an example. Accurate characterization of the surface oxygen exchange process is realized by developing thin and dense polycrystalline LSNO layers via a versatile spray-modified pressing method we invented before to avoid perceptible bulk diffusion contribution, surface enrichment and geometry complication...
March 28, 2016: Physical Chemistry Chemical Physics: PCCP
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