Bacterial survival is fraught with antagonism, including that deriving from viruses and competing bacterial cells. It is now appreciated that bacteria mount complex antiviral responses; however, whether a coordinated defense against bacterial threats is undertaken is not well understood. Previously, we showed that possess a danger-sensing pathway that is a critical fitness determinant during competition against other bacteria.
View Article and Find Full Text PDFWe report that there is a recent global expansion of numerous independent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with mutation L452R in the receptor-binding domain (RBD) of the spike protein. The massive emergence of L452R variants was first linked to lineage B.1.
View Article and Find Full Text PDFObjective: Sudantha® (SUD), a natural proprietary mixture of herbal extracts that has been incorporated into toothpaste, has been shown in two separate placebo controlled human clinical studies to promote gingival health; and reduce gingival bleeding and plaque formation. However, the herbal based anti-gingivitis mechanisms of Sudantha are not fully understood. The objective of this study was to determine the effect of Sudantha on dental plaque biofilms by investigating its effect on mono-culture biofilms of a primary colonizer, , .
View Article and Find Full Text PDFAbstract: The SARS-CoV-2 pandemic has presented new challenges to food manufacturers. During the early phase of the pandemic, several large outbreaks of coronavirus disease 2019 (COVID-19) occurred in food manufacturing plants resulting in deaths and economic loss, with approximately 15% of personnel diagnosed as asymptomatic for COVID-19. Spread by asymptomatic and presymptomatic individuals has been implicated in large outbreaks of COVID-19.
View Article and Find Full Text PDFThe outer membrane (OM) of Gram-negative bacteria serves as a selective permeability barrier that allows entry of essential nutrients while excluding toxic compounds, including antibiotics. The OM is asymmetric and contains an outer leaflet of lipopolysaccharides (LPS) or lipooligosaccharides (LOS) and an inner leaflet of glycerophospholipids (GPL). We screened transposon mutants and identified a number of mutants with OM defects, including an ABC transporter system homologous to the Mla system in We further show that this opportunistic, antibiotic-resistant pathogen uses this multicomponent protein complex and ATP hydrolysis at the inner membrane to promote GPL export to the OM.
View Article and Find Full Text PDFThe outer membranes of Gram-negative bacteria and mitochondria contain proteins with a distinct β-barrel tertiary structure that could function as a molecular pattern recognized by the innate immune system. Here, we report that purified outer membrane proteins (OMPs) from different bacterial and mitochondrial sources triggered the induction of autophagy-related endosomal acidification, LC3B lipidation, and p62 degradation. Furthermore, OMPs reduced the phosphorylation and therefore activation of the multiprotein complex mTORC2 and its substrate Akt in macrophages and epithelial cells.
View Article and Find Full Text PDFThe bacterial second messenger cyclic diguanosine monophosphate (c-di-GMP) is a key regulator of cellular motility, the cell cycle, and biofilm formation with its resultant antibiotic tolerance, which can make chronic infections difficult to treat. Therefore, diguanylate cyclases, which regulate the spatiotemporal production of c-di-GMP, might be attractive drug targets for control of biofilm formation that is part of chronic infections. We present a FRET-based biochemical high-throughput screening approach coupled with detailed structure-activity studies to identify synthetic small-molecule modulators of the diguanylate cyclase DgcA from Caulobacter crescentus.
View Article and Find Full Text PDFBacteria in polymicrobial habitats contend with a persistent barrage of competitors, often under rapidly changing environmental conditions . The direct antagonism of competitor cells is thus an important bacterial survival strategy . Towards this end, many bacterial species employ an arsenal of antimicrobial effectors with multiple activities; however, the benefits conferred by the simultaneous deployment of diverse toxins are unknown.
View Article and Find Full Text PDFThe Firmicutes are a phylum of bacteria that dominate numerous polymicrobial habitats of importance to human health and industry. Although these communities are often densely colonized, a broadly distributed contact-dependent mechanism of interbacterial antagonism utilized by Firmicutes has not been elucidated. Here we show that proteins belonging to the LXG polymorphic toxin family present in mediate cell contact- and Esx secretion pathway-dependent growth inhibition of diverse Firmicute species.
View Article and Find Full Text PDFThe nosocomial pathogen Acinetobacter baumannii is a frequent cause of hospital-acquired infections worldwide and is a challenge for treatment due to its evolved resistance to antibiotics, including carbapenems. Here, to gain insight on A. baumannii antibiotic resistance mechanisms, we analyse the protein interaction network of a multidrug-resistant A.
View Article and Find Full Text PDFWhen bacterial lineages make the transition from free-living to permanent association with hosts, they can undergo massive gene losses, for which the selective forces within host tissues are unknown. We identified here melanogenic clinical isolates of Pseudomonas aeruginosa with large chromosomal deletions (66 to 270 kbp) and characterized them to investigate how they were selected. When compared with their wild-type parents, melanogenic mutants (i) exhibited a lower fitness in growth conditions found in human tissues, such as hyperosmolarity and presence of aminoglycoside antibiotics, (ii) narrowed their metabolic spectrum with a growth disadvantage with particular carbon sources, including aromatic amino acids and acyclic terpenes, suggesting a reduction of metabolic flexibility.
View Article and Find Full Text PDFRationale: Pseudomonas aeruginosa undergoes phenotypic changes during cystic fibrosis (CF) lung infection. Although mucoidy is traditionally associated with transition to chronic infection, we hypothesized that additional in vitro phenotypes correlate with this transition and contribute to disease.
Objectives: To characterize the relationships between in vitro P.
Background: Pseudomonas aeruginosa is a key respiratory pathogen in people with cystic fibrosis (CF). Due to its association with lung disease progression, initial detection of P. aeruginosa in CF respiratory cultures usually results in antibiotic treatment with the goal of eradication.
View Article and Find Full Text PDFTransposon-based mutagenesis of bacterial genomes is a powerful method to identify genetic elements that control specific phenotypes. The most frequently used transposon tools in Pseudomonas aeruginosa are based either on Himar1 mariner or Tn5 transposases, both of which have been used to generate nonredundant mutant libraries in P. aeruginosa.
View Article and Find Full Text PDFIndividual cell heterogeneity is commonly observed within populations, although its molecular basis is largely unknown. Previously, using FRET-based microscopy, we observed heterogeneity in cellular c-di-GMP levels. In this study, we show that c-di-GMP heterogeneity in Pseudomonas aeruginosa is promoted by a specific phosphodiesterase partitioned after cell division.
View Article and Find Full Text PDFPseudomonas aeruginosa is a Gram-negative bacterium found in natural environments including plants, soils and warm moist surfaces. This organism is also in the top ten of nosocomial pathogens, and prevalent in cystic fibrosis (CF) lung infections. The ability of P.
View Article and Find Full Text PDFc-di-GMP is a bacterial second messenger that is enzymatically synthesized and degraded in response to environmental signals. Cellular processes are affected when c-di-GMP binds to receptors which include proteins that contain the PilZ domain. Although each c-di-GMP synthesis or degradation enzyme metabolizes the same molecule, many of these enzymes can be linked to specific downstream processes.
View Article and Find Full Text PDFBacterial resistance to β-lactams may rely on acquired β-lactamases encoded by class 1 integron-borne genes. Rearrangement of integron cassette arrays is mediated by the integrase IntI1. It has been previously established that integrase expression can be activated by the SOS response in vitro, leading to speculation that this is an important clinical mechanism of acquiring resistance.
View Article and Find Full Text PDFCyclic-di-GMP (c-di-GMP) regulates many important bacterial processes. Freely diffusible intracellular c-di-GMP is determined by the action of metabolizing enzymes that allow integration of numerous input signals. c-di-GMP specifically regulates multiple cellular processes by binding to diverse target molecules.
View Article and Find Full Text PDFThe bacterial second messenger cyclic diguanosine monophosphate (c-di-GMP) regulates cellular motility and the synthesis of organelles and molecules that promote adhesion to a variety of biological and nonbiological surfaces. These properties likely require tight spatial and temporal regulation of c-di-GMP concentration. We have developed genetically encoded fluorescence resonance energy transfer (FRET)-based biosensors to monitor c-di-GMP concentrations within single bacterial cells by microscopy.
View Article and Find Full Text PDFMicrobes are subjected to selective pressures during chronic infections of host tissues. Pseudomonas aeruginosa isolates with inactivating mutations in the transcriptional regulator LasR are frequently selected within the airways of people with cystic fibrosis (CF), and infection with these isolates has been associated with poorer lung function outcomes. The mechanisms underlying selection for lasR mutation are unknown but have been postulated to involve the abundance of specific nutrients within CF airway secretions.
View Article and Find Full Text PDFData-dependent precursor ion selection is widely used in shotgun proteomics to profile the protein components of complex samples. Although very popular, this bottom-up method presents major drawbacks in terms of detectable dynamic range. Here, we demonstrate the superior performance of a data-independent method we term precursor acquisition independent from ion count (PAcIFIC).
View Article and Find Full Text PDFBackground: Pseudomonas aeruginosa with mutations in the transcriptional regulator LasR chronically infect the airways of people with cystic fibrosis (CF), yet the prevalence and clinical implications of lasR mutant infection are unknown.
Methods: In an exploratory study, we screened 166 P. aeruginosa isolates from 58 CF patients for LasR inactivation and mucoidy, and compared clinical characteristics among source patients.
Gas-phase fractionation (GPF) is an efficient and straightforward method to increase proteome coverage. In this report, optimal m/z ranges were calculated based on genomic complexity and experimental data. Then, theoretical precursor ion densities were calculated in silico from various organisms' genomes and found to corroborate the empirical selection of m/z ranges based on ion density mapping.
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