Carbon and clay nanoparticles induce minimal stress responses in gram negative bacteria and eukaryotic fish cells

2012 ◽  
Vol 29 (8) ◽  
pp. 961-968 ◽  
Author(s):  
Alicia A. Taylor ◽  
Gary M. Aron ◽  
Gary W. Beall ◽  
Nihal Dharmasiri ◽  
Yixin Zhang ◽  
...  
Keyword(s):  
Stress Responses ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Clay Nanoparticles ◽  
Fish Cells ◽  
Minimal Stress

scholarly journals The Rcs Phosphorelay Is a Cell Envelope Stress Response Activated by Peptidoglycan Stress and Contributes to Intrinsic Antibiotic Resistance

2008 ◽  
Vol 190 (6) ◽  
pp. 2065-2074 ◽  
Author(s):  
Mary E. Laubacher ◽  
Sarah E. Ades
Keyword(s):  
Outer Membrane ◽  
Single Molecule ◽  
Stress Responses ◽  
Structural Integrity ◽  
Cell Envelope ◽  
Gram Negative Bacteria ◽  
Intrinsic Resistance ◽  
Gram Negative ◽  
Envelope Stress ◽  
Peptidoglycan Layer

ABSTRACTGram-negative bacteria possess stress responses to maintain the integrity of the cell envelope. Stress sensors monitor outer membrane permeability, envelope protein folding, and energization of the inner membrane. The systems used by gram-negative bacteria to sense and combat stress resulting from disruption of the peptidoglycan layer are not well characterized. The peptidoglycan layer is a single molecule that completely surrounds the cell and ensures its structural integrity. During cell growth, new peptidoglycan subunits are incorporated into the peptidoglycan layer by a series of enzymes called the penicillin-binding proteins (PBPs). To explore how gram-negative bacteria respond to peptidoglycan stress, global gene expression analysis was used to identifyEscherichia colistress responses activated following inhibition of specific PBPs by the β-lactam antibiotics amdinocillin (mecillinam) and cefsulodin. Inhibition of PBPs with different roles in peptidoglycan synthesis has different consequences for cell morphology and viability, suggesting that not all perturbations to the peptidoglycan layer generate equivalent stresses. We demonstrate that inhibition of different PBPs resulted in both shared and unique stress responses. The regulation of capsular synthesis (Rcs) phosphorelay was activated by inhibition of all PBPs tested. Furthermore, we show that activation of the Rcs phosphorelay increased survival in the presence of these antibiotics, independently of capsule synthesis. Both activation of the phosphorelay and survival required signal transduction via the outer membrane lipoprotein RcsF and the response regulator RcsB. We propose that the Rcs pathway responds to peptidoglycan damage and contributes to the intrinsic resistance ofE. colito β-lactam antibiotics.

scholarly journals A Stress Response Monitoring Lipoprotein Trafficking to the Outer Membrane

mBio ◽  
2019 ◽  
Vol 10 (3) ◽  
Author(s):  
Kerrie L. May ◽  
Kelly M. Lehman ◽  
Angela M. Mitchell ◽  
Marcin Grabowicz
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Outer Membrane ◽  
Stress Responses ◽  
Stress System ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Content Type ◽  
Essential Components ◽  
Trafficking Defects

ABSTRACTGram-negative bacteria produce lipid-anchored lipoproteins that are trafficked to their outer membrane (OM). These lipoproteins are essential components in each of the molecular machines that build the OM, including the Bam machine that assembles β-barrel proteins and the Lpt pathway that transports lipopolysaccharide. Stress responses are known to monitor Bam and Lpt function, yet no stress system has been found that oversees the fundamental process of lipoprotein trafficking. We used genetic and chemical biology approaches to induce several different lipoprotein trafficking stresses inEscherichia coli. Our results identified the Cpx two-component system as a stress response for monitoring trafficking. Cpx is activated by trafficking defects and is required to protect the cell against the consequence of the resulting stress. The OM-targeted lipoprotein NlpE acts as a sensor that allows Cpx to gauge trafficking efficiency. We reveal that NlpE signals to Cpx while it is transiting the inner membrane (IM)en routeto the OM and that only a small highly conserved N-terminal domain is required for signaling. We propose that defective trafficking causes NlpE to accumulate in the IM, activating Cpx to mount a transcriptional response that protects cells. Furthermore, we reconcile this new role of NlpE in signaling trafficking defects with its previously proposed role in sensing copper (Cu) stress by demonstrating that Cu impairs acylation of lipoproteins and, consequently, their trafficking to the OM.IMPORTANCEThe outer membrane built by Gram-negative bacteria such asEscherichia coliforms a barrier that prevents antibiotics from entering the cell, limiting clinical options at a time of prevalent antibiotic resistance. Stress responses ensure that barrier integrity is continuously maintained. We have identified the Cpx signal transduction system as a stress response that monitors the trafficking of lipid-anchored lipoproteins to the outer membrane. These lipoproteins are needed by every machine that builds the outer membrane. Cpx monitors just one lipoprotein, NlpE, to detect the efficiency of lipoprotein trafficking in the cell. NlpE and Cpx were previously shown to play a role in resistance to copper. We show that copper blocks lipoprotein trafficking, reconciling old and new observations. Copper is an important element in innate immunity against pathogens, and our findings suggest that NlpE and Cpx helpE. colisurvive the assault of copper on a key outer membrane assembly pathway.

scholarly journals Surviving Reactive Chlorine Stress: Responses of Gram-Negative Bacteria to Hypochlorous Acid

2020 ◽  
Vol 8 (8) ◽  
pp. 1220 ◽  
Author(s):  
Waleska Stephanie da Cruz Nizer ◽  
Vasily Inkovskiy ◽  
Joerg Overhage
Keyword(s):  
Conformational Changes ◽  
Stress Responses ◽  
Adaptive Response ◽  
Molecular Mechanisms ◽  
Hypochlorous Acid ◽  
Transcriptional Regulators ◽  
Cellular Damage ◽  
Membrane Properties ◽  
Gram Negative Bacteria ◽  
Gram Negative

Sodium hypochlorite (NaOCl) and its active ingredient, hypochlorous acid (HOCl), are the most commonly used chlorine-based disinfectants. HOCl is a fast-acting and potent antimicrobial agent that interacts with several biomolecules, such as sulfur-containing amino acids, lipids, nucleic acids, and membrane components, causing severe cellular damage. It is also produced by the immune system as a first-line of defense against invading pathogens. In this review, we summarize the adaptive responses of Gram-negative bacteria to HOCl-induced stress and highlight the role of chaperone holdases (Hsp33, RidA, Cnox, and polyP) as an immediate response to HOCl stress. We also describe the three identified transcriptional regulators (HypT, RclR, and NemR) that specifically respond to HOCl. Besides the activation of chaperones and transcriptional regulators, the formation of biofilms has been described as an important adaptive response to several stressors, including HOCl. Although the knowledge on the molecular mechanisms involved in HOCl biofilm stimulation is limited, studies have shown that HOCl induces the formation of biofilms by causing conformational changes in membrane properties, overproducing the extracellular polymeric substance (EPS) matrix, and increasing the intracellular concentration of cyclic-di-GMP. In addition, acquisition and expression of antibiotic resistance genes, secretion of virulence factors and induction of the viable but nonculturable (VBNC) state has also been described as an adaptive response to HOCl. In general, the knowledge of how bacteria respond to HOCl stress has increased over time; however, the molecular mechanisms involved in this stress response is still in its infancy. A better understanding of these mechanisms could help understand host-pathogen interactions and target specific genes and molecules to control bacterial spread and colonization.

scholarly journals BING, a novel antimicrobial peptide isolated from Japanese medaka plasma, targets bacterial envelope stress response by suppressing cpxR expression

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Miao Dong ◽  
Shu Hin Kwok ◽  
Joseph L. Humble ◽  
Yimin Liang ◽  
Sze Wing Tang ◽  
...  
Keyword(s):  
Stress Responses ◽  
Pathogenic Bacteria ◽  
Efflux Pump ◽  
Gram Negative Bacteria ◽  
Promising Alternative ◽  
Gram Negative ◽  
Upstream Regulator ◽  
Mammalian Cell Lines ◽  
Envelope Stress ◽  
Peptidyl Prolyl Isomerases

AbstractAntimicrobial peptides (AMPs) have emerged as a promising alternative to small molecule antibiotics. Although AMPs have previously been isolated in many organisms, efforts on the systematic identification of AMPs in fish have been lagging. Here, we collected peptides from the plasma of medaka (Oryzias latipes) fish. By using mass spectrometry, 6399 unique sequences were identified from the isolated peptides, among which 430 peptides were bioinformatically predicted to be potential AMPs. One of them, a thermostable 13-residue peptide named BING, shows a broad-spectrum toxicity against pathogenic bacteria including drug-resistant strains, at concentrations that presented relatively low toxicity to mammalian cell lines and medaka. Proteomic analysis indicated that BING treatment induced a deregulation of periplasmic peptidyl-prolyl isomerases in gram-negative bacteria. We observed that BING reduced the RNA level of cpxR, an upstream regulator of envelope stress responses. cpxR is known to play a crucial role in the development of antimicrobial resistance, including the regulation of genes involved in drug efflux. BING downregulated the expression of efflux pump components mexB, mexY and oprM in P. aeruginosa and significantly synergised the toxicity of antibiotics towards these bacteria. In addition, exposure to sublethal doses of BING delayed the development of antibiotic resistance. To our knowledge, BING is the first AMP shown to suppress cpxR expression in Gram-negative bacteria. This discovery highlights the cpxR pathway as a potential antimicrobial target.

scholarly journals Correlated transcriptional responses provide insights into the synergy mechanisms of the furazolidone, vancomycin and sodium deoxycholate triple combination in Escherichia coli

2021 ◽  
Author(s):  
Catrina Olivera ◽  
Murray P. Cox ◽  
Gareth J Rowlands ◽  
Jasna Rakonjac
Keyword(s):  
Escherichia Coli ◽  
Antibiotic Resistance ◽  
Stress Responses ◽  
Sodium Deoxycholate ◽  
Resistance Mechanisms ◽  
World Health ◽  
Gram Negative Bacteria ◽  
Iron Starvation ◽  
Transcriptional Responses ◽  
Gram Negative

Effective therapeutic options are urgently needed to tackle antibiotic resistance. Furazolidone (FZ), vancomycin (VAN), and sodium deoxycholate (DOC) show promise as their combination can synergistically inhibit the growth of, and kill, multidrug-resistant Gram-negative bacteria that are classified as critical priority by the World Health Organization. Here, we investigated the mechanisms of action and synergy of this drug combination using a transcriptomics approach in the model bacterium Escherichia coli. We show that FZ and DOC elicit highly similar gene perturbations indicative of iron starvation, decreased respiration and metabolism, and translational stress. In contrast, VAN induced envelope stress responses, in agreement with its known role in peptidoglycan synthesis inhibition. FZ induced the SOS response consistent with its DNA damaging effects, but we demonstrate that using FZ in combination with the other two compounds enables use of lower dosages and largely mitigates its mutagenic effects. Based on the gene expression changes identified, we propose a synergy mechanism where the combined effects of FZ, VAN, and DOC amplify damage to Gram-negative bacteria while simultaneously suppressing antibiotic resistance mechanisms.

scholarly journals Recognition of β-Strand Motifs by RseB Is Required for σEActivity in Escherichia coli

2011 ◽  
Vol 193 (22) ◽  
pp. 6179-6186 ◽  
Author(s):  
Adam Kulp ◽  
Meta J. Kuehn
Keyword(s):  
Stress Response ◽  
Stress Responses ◽  
Outer Membrane Proteins ◽  
Harsh Environments ◽  
Gram Negative Bacteria ◽  
Dependent Manner ◽  
Gram Negative ◽  
Stress Response Pathway ◽  
Envelope Stress ◽  
Different Types

Gram-negative bacteria react to misfolded proteins in the envelope through a myriad of different stress response pathways. This cohort of pathways allows the bacteria to specifically respond to different types of damage, and many of these have been discovered to have key roles in the virulence of bacterial pathogens. Misfolded outer membrane proteins (OMPs) are typically recognized by the σEpathway, a highly conserved envelope stress response pathway. We examined the features of misfolded OMPs with respect to their ability to generate envelope stress responses. We determined that the secondary structure, particularly the potential to form β strands, is critical to inducing the σEresponse in an RseB-dependent manner. The sequence of the potential β-strand motif modulates the strength of the σEresponse generated by the constructs. By understanding the details of how such stress response pathways are activated, we can gain a greater understanding of how bacteria survive in harsh environments.

Bacterial-Mucosal Cell Junctional Complexes

1974 ◽  
Vol 32 ◽  
pp. 144-145
Author(s):  
Roger C. Wagner
Keyword(s):  
Intestinal Wall ◽  
Rat Colon ◽  
Mucosal Cell ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Mucosal Cells ◽  
Mucosal Lining ◽  
Degenerative Alterations ◽  
Junctional Complexes ◽  
Intestinal Mucosal Cells

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.

Rapid demonstration of septic or infectious arthritis due to Gram-negative bacteria

1992 ◽  
Vol 50 (1) ◽  
pp. 686-687
Author(s):  
Jacob S. Hanker ◽  
Paul R. Gross ◽  
Beverly L. Giammara
Keyword(s):  
Chronic Arthritis ◽  
Blood Cultures ◽  
Gram Negative Bacteria ◽  
Infectious Arthritis ◽  
Bacterial Arthritis ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria

Blood cultures are positive in approximately only 50 per cent of the patients with nongonococcal bacterial infectious arthritis and about 20 per cent of those with gonococcal arthritis. But the concept that gram-negative bacteria could be involved even in chronic arthritis is well-supported. Gram stains are more definitive in staphylococcal arthritis caused by gram-positive bacteria than in bacterial arthritis due to gram-negative bacteria. In the latter situation where gram-negative bacilli are the problem, Gram stains are helpful for 50% of the patients; they are only helpful for 25% of the patients, however, where gram-negative gonococci are the problem. In arthritis due to gram-positive Staphylococci. Gramstained smears are positive for 75% of the patients.

Ultrastructure of periplasmic bodies in gram-negative bacteria

1990 ◽  
Vol 48 (3) ◽  
pp. 640-641
Author(s):  
Xie Nianming ◽  
Ding Shaoqing ◽  
Wang Luping ◽  
Yuan Zenglin ◽  
Zhan Guolai ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Campylobacter Jejuni ◽  
Proteus Mirabilis ◽  
Shigella Flexneri ◽  
Morphological Description ◽  
Gram Negative Bacteria ◽  
Periplasmic Space ◽  
Clostridium Tetani ◽  
Gram Negative ◽  
Brucella Canis

Perhaps the data about periplasmic enzymes are obtained through biochemical methods but lack of morphological description. We have proved the existence of periplasmic bodies by electron microscope and described their ultrastructures. We hope this report may draw the attention of biochemists and mrophologists to collaborate on researches in periplasmic enzymes or periplasmic bodies with each other.One or more independent bodies may be seen in the periplasmic space between outer and inner membranes of Gram-negative bacteria, which we called periplasmic bodies. The periplasmic bodies have been found in seven species of bacteria at least, including the Pseudomonas aeroginosa. Shigella flexneri, Echerichia coli. Yersinia pestis, Campylobacter jejuni, Proteus mirabilis, Clostridium tetani. Vibrio cholerae and Brucella canis.

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