scholarly journals The RNA-Binding Chaperone Hfq Is an Important Global Regulator of Gene Expression in Pasteurella multocida and Plays a Crucial Role in Production of a Number of Virulence Factors, Including Hyaluronic Acid Capsule

2016 ◽  
Vol 84 (5) ◽  
pp. 1361-1370 ◽  
Author(s):  
Marianne Mégroz ◽  
Oded Kleifeld ◽  
Amy Wright ◽  
David Powell ◽  
Paul Harrison ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Virulence Factors ◽  
Crucial Role ◽  
Pasteurella Multocida ◽  
Rna Binding ◽  
Content Type ◽  
Protein Levels ◽  
Filamentous Hemagglutinin ◽  
Proteomic Analyses ◽  
Hyaluronic Acid Capsule

The Gram-negative bacteriumPasteurella multocidais the causative agent of a number of economically important animal diseases, including avian fowl cholera. NumerousP. multocidavirulence factors have been identified, including capsule, lipopolysaccharide (LPS), and filamentous hemagglutinin, but little is known about how the expression of these virulence factors is regulated. Hfq is an RNA-binding protein that facilitates riboregulation via interaction with small noncoding RNA (sRNA) molecules and their mRNA targets. Here, we show that aP. multocidahfqmutant produces significantly less hyaluronic acid capsule during all growth phases and displays reducedin vivofitness. Transcriptional and proteomic analyses of thehfqmutant during mid-exponential-phase growth revealed altered transcript levels for 128 genes and altered protein levels for 78 proteins. Further proteomic analyses of thehfqmutant during the early exponential growth phase identified 106 proteins that were produced at altered levels. Both the transcript and protein levels for genes/proteins involved in capsule biosynthesis were reduced in thehfqmutant, as were the levels of the filamentous hemagglutinin protein PfhB2 and its secretion partner LspB2. In contrast, there were increased expression levels of three LPS biosynthesis genes, encoding proteins involved in phosphocholine and phosphoethanolamine addition to LPS, suggesting that these genes are negatively regulated by Hfq-dependent mechanisms. Taken together, these data provide the first evidence that Hfq plays a crucial role in regulating the global expression ofP. multocidagenes, including the regulation of keyP. multocidavirulence factors, capsule, LPS, and filamentous hemagglutinin.

scholarly journals Borrelia burgdorferiSpoVG DNA- and RNA-Binding Protein Modulates the Physiology of the Lyme Disease Spirochete

2018 ◽  
Vol 200 (12) ◽  
Author(s):  
Christina R. Savage ◽  
Brandon L. Jutras ◽  
Aaron Bestor ◽  
Kit Tilly ◽  
Patricia A. Rosa ◽  
...  
Keyword(s):  
Lyme Disease ◽  
Rna Binding ◽  
Culture Conditions ◽  
Altered Expression ◽  
Content Type ◽  
Protein Levels ◽  
Dna And Rna ◽  
Physiological Alterations ◽  
Bacterial Replication ◽  
Dna And Rna Binding

ABSTRACTThe SpoVG protein ofBorrelia burgdorferi, the Lyme disease spirochete, binds to specific sites of DNA and RNA. The bacterium regulates transcription ofspoVGduring the natural tick-mammal infectious cycle and in response to some changes in culture conditions. Bacterial levels ofspoVGmRNA and SpoVG protein did not necessarily correlate, suggesting that posttranscriptional mechanisms also control protein levels. Consistent with this, SpoVG binds to its own mRNA, adjacent to the ribosome-binding site. SpoVG also binds to two DNA sites in theglpFKDoperon and to two RNA sites inglpFKDmRNA; that operon encodes genes necessary for glycerol catabolism and is important for colonization in ticks. In addition, spirochetes engineered to dysregulatespoVGexhibited physiological alterations.IMPORTANCEB. burgdorferipersists in nature by cycling between ticks and vertebrates. Little is known about how the bacterium senses and adapts to each niche of the cycle. The present studies indicate thatB. burgdorfericontrols production of SpoVG and that this protein binds to specific sites of DNA and RNA in the genome and transcriptome, respectively. Altered expression ofspoVGexerts effects on bacterial replication and other aspects of the spirochete's physiology.

scholarly journals Emergence of a New Highly Successful Acapsular Group A Streptococcus Clade of Genotype emm89 in the United Kingdom

mBio ◽  
2015 ◽  
Vol 6 (4) ◽  
Author(s):  
Claire E. Turner ◽  
James Abbott ◽  
Theresa Lamagni ◽  
Matthew T. G. Holden ◽  
Sophia David ◽  
...  
Keyword(s):  
United Kingdom ◽  
Hyaluronic Acid ◽  
Genome Sequencing ◽  
Virulence Factors ◽  
Invasive Disease ◽  
Whole Genome ◽  
The United Kingdom ◽  
Streptolysin O ◽  
Group A ◽  
Hyaluronic Acid Capsule

ABSTRACTGroup AStreptococcus(GAS) genotypeemm89 is increasingly recognized as a leading cause of disease worldwide, yet factors that underlie the success of thisemmtype are unknown. Surveillance identified a sustained nationwide increase inemm89 invasive GAS disease in the United Kingdom, prompting longitudinal investigation of this genotype. Whole-genome sequencing revealed a recent dramatic shift in theemm89 population with the emergence of a new clade that increased to dominance over previousemm89 variants. Temporal analysis indicated that the clade arose in the early 1990s but abruptly increased in prevalence in 2008, coinciding with an increased incidence ofemm89 infections. Although standard variable typing regions (emmsubtype,teetype,softype, and multilocus sequence typing [MLST]) remained unchanged, uniquely the emergent clade had undergone six distinct regions of homologous recombination across the genome compared to the rest of the sequencedemm89 population. Two of these regions affected known virulence factors, the hyaluronic acid capsule and the toxins NADase and streptolysin O. Unexpectedly, and in contrast to the rest of the sequencedemm89 population, the emergent clade-associated strains were genetically acapsular, rendering them unable to produce the hyaluronic acid capsule. The emergent clade-associated strains had also acquired an NADase/streptolysin O locus nearly identical to that found inemm12 and modernemm1 strains but different from the rest of the sequencedemm89 population. The emergent clade-associated strains had enhanced expression of NADase and streptolysin O. The genome remodeling in the new clade variant and the resultant altered phenotype appear to have conferred a selective advantage over otheremm89 variants and may explain the changes observed inemm89 GAS epidemiology.IMPORTANCESudden upsurges or epidemic waves are common features of group A streptococcal disease. Although the mechanisms behind such changes are largely unknown, they are often associated with an expansion of a single genotype within the population. Using whole-genome sequencing, we investigated a nationwide increase in invasive disease caused by the genotypeemm89 in the United Kingdom. We identified a new clade variant that had recently emerged in theemm89 population after having undergone several core genomic recombination-related changes, two of which affected known virulence factors. An unusual finding of the new variant was the loss of the hyaluronic acid capsule, previously thought to be essential for causing invasive disease. A further genomic adaptation in the NADase/streptolysin O locus resulted in enhanced production of these toxins. Recombination-related genome remodeling is clearly an important mechanism in group AStreptococcusthat can give rise to more successful and potentially more pathogenic variants.

M-protein gene-type distribution and hyaluronic acid capsule in group AStreptococcusclinical isolates in Chile: association ofemmgene markers withcsrRalleles

2011 ◽  
Vol 140 (7) ◽  
pp. 1286-1295 ◽  
Author(s):  
A. WOZNIAK ◽  
P. ROJAS ◽  
C. RODRÍGUEZ ◽  
A. UNDABARRENA ◽  
C. GARATE ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Virulence Factors ◽  
Protein Gene ◽  
Developed Countries ◽  
M Protein ◽  
Pacific Island ◽  
Non Invasive ◽  
Sterile Site ◽  
Hyaluronic Acid Capsule ◽  
The Relationship

SUMMARYStreptococcus pyogenescauses a variety of infections because of virulence factors such as capsular hyaluronic acid and M protein. The aim of this study was to determineemmtypes and capsule phenotype in 110 isolates ofS. pyogenesfrom patients with invasive (sterile sites) and non-invasive (mainly pharyngitis) infections in Chile, and the relationship between both virulence factors. The most abundant types found wereemm12,emm1,emm4andemm28and their distribution was similar to that seen in Latin America and developed countries, but very different from that in Asia and Pacific Island countries. Ten of 16emmtypes identified in pharyngeal isolates were found in sterile-site isolates, and three of nineemmtypes of sterile-site isolates occurred in pharyngeal isolates; threeemmsubtypes were novel. The amount of hyaluronic acid was significantly higher in sterile-site isolates but did not differ substantially amongemmtypes. Only three isolates were markedly capsulate and two of them had mutations in thecsrRgene that codes for a repressor of capsule synthesis genes. We found a non-random association betweenemmtypes andcsrRgene alleles suggesting that horizontal gene transfer is not freely occurring in the population.

Molecular pathogenesis of the hyaluronic acid capsule of Pasteurella multocida

2020 ◽  
Vol 149 ◽  
pp. 104380
Author(s):  
Lijun Guan ◽  
Lin Zhang ◽  
Yun Xue ◽  
Jinqian Yang ◽  
Zhanqin Zhao
Keyword(s):  
Hyaluronic Acid ◽  
Pasteurella Multocida ◽  
Molecular Pathogenesis ◽  
Hyaluronic Acid Capsule

scholarly journals Vitamin D and the Human Antimicrobial Peptide LL-37 Enhance Group A Streptococcus Resistance to Killing by Human Cells

mBio ◽  
2012 ◽  
Vol 3 (5) ◽  
Author(s):  
John F. Love ◽  
Hien J. Tran-Winkler ◽  
Michael R. Wessels
Keyword(s):  
Vitamin D ◽  
Hyaluronic Acid ◽  
Antimicrobial Peptide ◽  
Virulence Factors ◽  
Regulatory System ◽  
Innate Immune ◽  
Invasive Infection ◽  
Streptolysin O ◽  
Group A ◽  
Hyaluronic Acid Capsule

ABSTRACTThe CsrRS two-component regulatory system of group AStreptococcus(GAS;Streptococcus pyogenes) responds to subinhibitory concentrations of the human antimicrobial peptide LL-37. LL-37 signaling through CsrRS results in upregulation of genes that direct synthesis of virulence factors, including the hyaluronic acid capsule and streptolysin O (SLO). Here, we demonstrate that a consequence of this response is augmented GAS resistance to killing by human oropharyngeal keratinocytes, neutrophils, and macrophages. LL-37-induced upregulation of SLO and hyaluronic acid capsule significantly reduced internalization of GAS by keratinocytes and phagocytic killing by neutrophils and macrophages. Because vitamin D induces LL-37 production by macrophages, we tested its effect on macrophage killing of GAS. In contrast to the reported enhancement of macrophage function in relation to other pathogens, treatment of macrophages with 1α,25-dihydroxy-vitamin D3 paradoxically reduced the ability of macrophages to control GAS infection. These observations demonstrate that LL-37 signals through CsrRS to induce a virulence phenotype in GAS characterized by heightened resistance to ingestion and killing by both epithelial cells and phagocytes. By inducing LL-37 production in macrophages, vitamin D may contribute to this paradoxical exacerbation of GAS infection.IMPORTANCEIt remains poorly understood why group AStreptococcus(GAS) causes asymptomatic colonization or localized throat inflammation in most individuals but rarely progresses to invasive infection. The human antimicrobial peptide LL-37, which is produced as part of the innate immune response to GAS infection, signals through the GAS CsrRS two-component regulatory system to upregulate expression of multiple virulence factors. This study reports that two CsrRS-regulated GAS virulence factors—streptolysin O and the hyaluronic acid capsule—are critical in LL-37-induced resistance of GAS to killing by human throat epithelial cells and by neutrophils and macrophages. Vitamin D, which increases LL-37 production in macrophages, has the paradoxical effect of increasing GAS resistance to macrophage-mediated killing. In this way, the human innate immune response may promote the transition from GAS colonization to invasive infection.

scholarly journals E1210, a New Broad-Spectrum Antifungal, Suppresses Candida albicans Hyphal Growth through Inhibition of Glycosylphosphatidylinositol Biosynthesis

2011 ◽  
Vol 56 (2) ◽  
pp. 960-971 ◽  
Author(s):  
Nao-aki Watanabe ◽  
Mamiko Miyazaki ◽  
Takaaki Horii ◽  
Koji Sagane ◽  
Kappei Tsukahara ◽  
...  
Keyword(s):  
Candida Albicans ◽  
Virulence Factors ◽  
Inhibitory Activity ◽  
Biofilm Formation ◽  
Protein A ◽  
Hyphal Growth ◽  
Tube Formation ◽  
Protein Maturation ◽  
Content Type ◽  
Protein Levels

ABSTRACTContinued research toward the development of new antifungals that act via inhibition of glycosylphosphatidylinositol (GPI) biosynthesis led to the design of E1210. In this study, we assessed the selectivity of the inhibitory activity of E1210 againstCandida albicansGWT1(Orf19.6884) protein,Aspergillus fumigatusGWT1(AFUA_1G14870) protein, and humanPIG-Wprotein, which can catalyze the inositol acylation of GPI early in the GPI biosynthesis pathway, and then we assessed the effects of E1210 on keyC. albicansvirulence factors. E1210 inhibited the inositol acylation activity ofC. albicansGwt1p andA. fumigatusGwt1p with 50% inhibitory concentrations (IC50s) of 0.3 to 0.6 μM but had no inhibitory activity against human Pig-Wp even at concentrations as high as 100 μM. To confirm the inhibition of fungal GPI biosynthesis, expression ofALS1protein, a GPI-anchored protein, on the surfaces ofC. albicanscells treated with E1210 was studied and shown to be significantly lower than that on untreated cells. However, theALS1protein levels in the crude extract and theRHO1protein levels on the cell surface were found to be almost the same. Furthermore, E1210 inhibited germ tube formation, adherence to polystyrene surfaces, and biofilm formation ofC. albicansat concentrations above its MIC. These results suggested that E1210 selectively inhibited inositol acylation of fungus-specific GPI which would be catalyzed by Gwt1p, leading to the inhibition of GPI-anchored protein maturation, and also that E1210 suppressed the expression of some important virulence factors ofC. albicans, through its GPI biosynthesis inhibition.

scholarly journals Staphylococcus aureus Hyaluronidase Is a CodY-Regulated Virulence Factor

2014 ◽  
Vol 82 (10) ◽  
pp. 4253-4264 ◽  
Author(s):  
Carolyn B. Ibberson ◽  
Crystal L. Jones ◽  
Shweta Singh ◽  
Matthew C. Wise ◽  
Mark E. Hart ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Hyaluronic Acid ◽  
Virulence Factor ◽  
Bacterial Infections ◽  
Lung Pathology ◽  
Diverse Range ◽  
Content Type ◽  
Global Regulators ◽  
Protein Levels ◽  
Unit Reduction

ABSTRACTStaphylococcus aureusis a Gram-positive pathogen that causes a diverse range of bacterial infections. InvasiveS. aureusstrains secrete an extensive arsenal of hemolysins, immunomodulators, and exoenzymes to cause disease. Our studies have focused on the secreted enzyme hyaluronidase (HysA), which cleaves the hyaluronic acid polymer at the β-1,4 glycosidic bond. In the study described in this report, we have investigated the regulation and contribution of this enzyme toS. aureuspathogenesis. Using the Nebraska Transposon Mutant Library (NTML), we identified eight insertions that modulate extracellular levels of HysA activity. Insertions in thesigBoperon, as well as in genes encoding the global regulators SarA and CodY, significantly increased HysA protein levels and activity. By altering the availability of branched-chain amino acids, we further demonstrated CodY-dependent repression of HysA activity. Additionally, through mutation of the CodY binding box upstream ofhysA, the repression of HysA production was lost, suggesting that CodY is a direct repressor ofhysAexpression. To determine whether HysA is a virulence factor, a ΔhysAmutant of a community-associated methicillin-resistantS. aureus(CA-MRSA) USA300 strain was constructed and found to be attenuated in a neutropenic, murine model of pulmonary infection. Mice infected with this mutant strain exhibited a 4-log-unit reduction in bacterial burden in their lungs, as well as reduced lung pathology and increased levels of pulmonary hyaluronic acid, compared to mice infected with the wild-type, parent strain. Taken together, these results indicate thatS. aureushyaluronidase is a CodY-regulated virulence factor.

scholarly journals Trading Capsule for Increased Cytotoxin Production: Contribution to Virulence of a Newly Emerged Clade of emm89 Streptococcus pyogenes

mBio ◽  
2015 ◽  
Vol 6 (5) ◽  
Author(s):  
Luchang Zhu ◽  
Randall J. Olsen ◽  
Waleed Nasser ◽  
Ivan de la Riva Morales ◽  
James M. Musser
Keyword(s):  
Hyaluronic Acid ◽  
Streptococcus Pyogenes ◽  
Molecular Mechanisms ◽  
Great Majority ◽  
Whole Genome Sequence ◽  
Phylogenetic Groups ◽  
Content Type ◽  
Genetic Features ◽  
Clade 1 ◽  
Hyaluronic Acid Capsule

ABSTRACTStrains ofemm89Streptococcus pyogeneshave become one of the major causes of invasive infections worldwide in the last 10 years. We recently sequenced the genome of 1,125emm89strains and identified three major phylogenetic groups, designated clade 1, clade 2, and the epidemic clade 3. Epidemic clade 3 strains, which now cause the great majority of infections, have two distinct genetic features compared to clade 1 and clade 2 strains. First, all clade 3 organisms have a variant 3ngapromoter region pattern, which is associated with increased production of secreted cytolytic toxins SPN (S. pyogenesNADase) and SLO (streptolysin O). Second, all clade 3 strains lack thehasABClocus mediating hyaluronic acid capsule synthesis, whereas this locus is intact in clade 1 and clade 2 strains. We constructed isogenic mutant strains that produce different levels of SPN and SLO toxins and capsule (none, low, or high). Here we report thatemm89strains with elevated toxin production are significantly more virulent than low-toxin producers. Importantly, we also show that capsule production is dispensable for virulence in strains that already produce high levels of SPN and SLO. Our results provide new understanding about the molecular mechanisms contributing to the rapid emergence and molecular pathogenesis of epidemic clade 3emm89S. pyogenes.IMPORTANCES. pyogenes(group A streptococcus [GAS]) causes pharyngitis (“strep throat”), necrotizing fasciitis, and other human infections. Serious infections caused byemm89S. pyogenesstrains have recently increased in frequency in many countries. Based on whole-genome sequence analysis of 1,125 strains recovered from patients on two continents, we discovered that a newemm89clone, termed clade 3, has two distinct genetic features compared to its predecessors: (i) absence of the genes encoding antiphagocytic hyaluronic acid capsule virulence factor and (ii) increased production of the secreted cytolytic toxins SPN and SLO.emm89S. pyogenesstrains with the clade 3 phenotype (absence of capsule and high expression of SPN and SLO) are highly virulent in mice. These findings provide new understanding of how new virulent clones emerge and cause severe infections worldwide. This newfound knowledge ofS. pyogenesvirulence can be used to help understand future epidemics and conduct new translational research.

scholarly journals M Protein and Hyaluronic Acid Capsule Are Essential for In Vivo Selection of covRS Mutations Characteristic of Invasive Serotype M1T1 Group A Streptococcus

mBio ◽  
2010 ◽  
Vol 1 (4) ◽  
Author(s):  
Jason N. Cole ◽  
Morgan A. Pence ◽  
Maren von Köckritz-Blickwede ◽  
Andrew Hollands ◽  
Richard L. Gallo ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Virulence Factors ◽  
Gene Knockout ◽  
Genetic Switch ◽  
Host Defense Peptides ◽  
M1 Protein ◽  
Wide Range ◽  
Group A ◽  
Hyaluronic Acid Capsule

ABSTRACTThe initiation of hyperinvasive disease in group AStreptococcus(GAS) serotype M1T1 occurs by mutation within thecovRStwo-component regulon (namedcovRSforcontrolofvirulenceregulatorysensor kinase), which promotes resistance to neutrophil-mediated killing through the upregulation of bacteriophage-encoded Sda1 DNase. To determine whether other virulence factors contribute to this phase-switching phenomenon, we studied a panel of 10 isogenic GAS serotype M1T1 virulence gene knockout mutants. While loss of several individual virulence factors did not prevent GAScovRSswitchingin vivo, we found that M1 protein and hyaluronic acid capsule are indispensable for the switching phenotype, a phenomenon previously attributed uniquely to the Sda1 DNase. We demonstrate that like M1 protein and Sda1, capsule expression enhances survival of GAS serotype M1T1 within neutrophil extracellular traps. Furthermore, capsule shares with M1 protein a role in GAS resistance to human cathelicidin antimicrobial peptide LL-37. We conclude that a quorum of GAS serotype M1T1 virulence genes with cooperative roles in resistance to neutrophil extracellular killing is essential for the switch to a hyperinvasive phenotypein vivo.IMPORTANCEThe pathogen group AStreptococcus(GAS) causes a wide range of human infections ranging from the superficial “strep throat” to potentially life-threatening conditions, such as necrotizing fasciitis, also known as “flesh-eating disease.” A marked increase in the number of cases of severe invasive GAS infection during the last 30 years has been traced to the emergence and spread of a single clone of the M1T1 serotype. Recent studies have shown that GAS serotype M1T1 bacteria undergo a genetic “switch”in vivoto a hypervirulent state that allows dissemination into the bloodstream. The present study was undertaken to identify specific GAS serotype M1T1 virulence factors required for this switch to hypervirulence. The surface-anchored GAS M1 protein and hyaluronic acid capsule are found to be essential for the switching phenotype, and a novel role for capsule in GAS resistance to host defense peptides and neutrophil extracellular killing is revealed.

scholarly journals The Emergence of Successful Streptococcus pyogenes Lineages through Convergent Pathways of Capsule Loss and Recombination Directing High Toxin Expression

mBio ◽  
2019 ◽  
Vol 10 (6) ◽  
Author(s):  
Claire E. Turner ◽  
Matthew T. G. Holden ◽  
Beth Blane ◽  
Carolyne Horner ◽  
Sharon J. Peacock ◽  
...  
Keyword(s):  
Hyaluronic Acid ◽  
Gene Transfer ◽  
Homologous Recombination ◽  
Streptococcus Pyogenes ◽  
High Expression ◽  
Data Set ◽  
Altered Expression ◽  
Content Type ◽  
Hyaluronic Acid Capsule ◽  
Inactivating Mutations

ABSTRACT Gene transfer and homologous recombination in Streptococcus pyogenes has the potential to trigger the emergence of pandemic lineages, as exemplified by lineages of emm1 and emm89 that emerged in the 1980s and 2000s, respectively. Although near-identical replacement gene transfer events in the nga (NADase) and slo (streptolysin O) loci conferring high expression of these toxins underpinned the success of these lineages, extension to other emm genotype lineages is unreported. The emergent emm89 lineage was characterized by five regions of homologous recombination additional to nga-slo, including complete loss of the hyaluronic acid capsule synthesis locus hasABC, a genetic trait replicated in two other leading emm types and recapitulated by other emm types by inactivating mutations. We hypothesized that other leading genotypes may have undergone similar recombination events. We analyzed a longitudinal data set of genomes from 344 clinical invasive disease isolates representative of locations across England, dating from 2001 to 2011, and an international collection of S. pyogenes genomes representing 54 different genotypes and found frequent evidence of recombination events at the nga-slo locus predicted to confer higher toxin genotype. We identified multiple associations between recombination at this locus and inactivating mutations within hasAB, suggesting convergent evolutionary pathways in successful genotypes. This included common genotypes emm28 and emm87. The combination of no or low capsule and high expression of nga and slo may underpin the success of many emergent S. pyogenes lineages of different genotypes, triggering new pandemics, and could change the way S. pyogenes causes disease. IMPORTANCE Streptococcus pyogenes is a genetically diverse pathogen, with over 200 different genotypes defined by emm typing, but only a minority of these genotypes are responsible for the majority of human infection in high-income countries. Two prevalent genotypes associated with disease rose to international dominance following recombination of a toxin locus that conferred increased expression. Here, we found that recombination of this locus and promoter has occurred in other diverse genotypes, events that may allow these genotypes to expand in the population. We identified an association between the loss of hyaluronic acid capsule synthesis and high toxin expression, which we propose may be associated with an adaptive advantage. As S. pyogenes pathogenesis depends both on capsule and toxin production, new variants with altered expression may result in abrupt changes in the molecular epidemiology of this pathogen in the human population over time.

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