scholarly journals Construction of a complete set of Neisseria meningitidis defined mutants – the NeMeSys 2.0 collection – and its use for the phenotypic profiling of the genome of an important human pathogen

2020 ◽  
Author(s):  
Alastair Muir ◽  
Ishwori Gurung ◽  
Ana Cehovin ◽  
Adelme Bazin ◽  
David Vallenet ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Bacterial Species ◽  
Bacterial Pathogen ◽  
Essential Genes ◽  
Human Pathogen ◽  
Gene Encoding ◽  
Complete Collection ◽  
Protein Coding ◽  
Type Iv ◽  
Genome Information

AbstractOne of the great challenges in biology is to determine the function of millions of genes of unknown function. Even in model bacterial species, there is a sizeable proportion of such genes, which has fundamental and practical consequences. Here, we constructed a complete collection of defined mutants in protein-coding genes – named NeMeSys 2.0 – in the human pathogen Neisseria meningitidis, consisting of individual mutants in 1,584 non-essential genes. This effort identified 391 essential genes – broadly conserved in other bacteria – leading to a full overview of the essential meningococcal genome, associated with just four underlying basic biological functions: 1) expression of genome information, 2) preservation of genome information, 3) cell membrane structure/function, and 4) cytosolic metabolism. Subsequently, we illustrated the utility of the NeMeSys 2.0 collection for determining gene function by identifying 1) a novel and conserved family of histidinol-phosphatase, 2) 20 genes, including three new ones, involved in the biology of type IV pili, a widespread virulence factor, and 3) several conditionally essential genes found in regions of genome plasticity encoding antitoxins and/or immunity proteins, which become dispensable when the gene encoding the cognate toxin is deleted. These findings have implications beyond the meningococcus. The NeMeSys 2.0 collection is an invaluable resource paving the way for a global phenotypic landscape in a major human bacterial pathogen.

scholarly journals Construction of a complete set of Neisseria meningitidis mutants and its use for the phenotypic profiling of this human pathogen

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Alastair Muir ◽  
Ishwori Gurung ◽  
Ana Cehovin ◽  
Adelme Bazin ◽  
David Vallenet ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Bacterial Pathogen ◽  
Essential Genes ◽  
Gene Encoding ◽  
Complete Collection ◽  
Protein Coding ◽  
Type Iv ◽  
Membrane Structure And Function ◽  
Genes Encoding ◽  
Information Cell

Abstract The bacterium Neisseria meningitidis causes life-threatening meningitis and sepsis. Here, we construct a complete collection of defined mutants in protein-coding genes of this organism, identifying all genes that are essential under laboratory conditions. The collection, named NeMeSys 2.0, consists of individual mutants in 1584 non-essential genes. We identify 391 essential genes, which are associated with basic functions such as expression and preservation of genome information, cell membrane structure and function, and metabolism. We use this collection to shed light on the functions of diverse genes, including a gene encoding a member of a previously unrecognised class of histidinol-phosphatases; a set of 20 genes required for type IV pili function; and several conditionally essential genes encoding antitoxins and/or immunity proteins. We expect that NeMeSys 2.0 will facilitate the phenotypic profiling of a major human bacterial pathogen.

scholarly journals Genomic Analysis of Chilean Strains of Campylobacter jejuni from Human Faeces

2019 ◽  
Vol 2019 ◽  
pp. 1-12 ◽  
Author(s):  
Arturo Levican ◽  
Ignacio Ramos-Tapia ◽  
Isabel Briceño ◽  
Francisco Guerra ◽  
Benjamin Mena ◽  
...  
Keyword(s):  
Latin American ◽  
Bacterial Species ◽  
Bacterial Pathogen ◽  
Acute Diarrhoea ◽  
Genomic Analysis ◽  
Relevant Information ◽  
Human Infection ◽  
Secretion Systems ◽  
Association Analyses ◽  
Type Iv

Campylobacter spp., especially C. jejuni, are recognized worldwide as the bacterial species that most commonly cause food-related diarrhea. C. jejuni possesses many different virulence factors, has the ability to survive in different reservoirs, and has shown among isolates the emergence of Antimicrobial Resistance (AMR). Genome association analyses of this bacterial pathogen have contributed to a better understanding of its pathogenic and AMR associated determinants. However, the epidemiological information of these bacteria in Latin American countries is scarce and no genomic information is available in public databases from isolates in these countries. Considering this, the present study is aimed to describe the genomic traits from representative Campylobacter spp. strains recovered from faecal samples of patients with acute diarrhoea from Valparaíso, Chile. Campylobacter spp. was detected from the faeces of 28 (8%) out of 350 patients with acute diarrhoea, mainly from young adults and children, and 26 (93%) of the isolates corresponded to C. jejuni. 63% of the isolates were resistant to ciprofloxacin, 25.9% to tetracycline, and 3.5% to erythromycin. Three isolates were selected for WGS on the basis of their flaA-RFLP genotype. They belonged to the multilocus sequence typing (MLST) clonal clomplex (CC) 21(PUCV-1), CC-48 (PUCV-3), and CC-353 (PUCV-2) and presented several putative virulence genes, including the Type IV and Type VI Secretion Systems, as well as AMR-associated genes in agreement with their susceptibility pattern. On the basis of the wgMLST, they were linked to strains from poultry and ruminants. These are the first genomes of Chilean C. jejuni isolates available in public databases and they provide relevant information about the C. jejuni isolates associated with human infection in this country.

scholarly journals Neisseria meningitidis Polynucleotide Phosphorylase Affects Aggregation, Adhesion, and Virulence

2016 ◽  
Vol 84 (5) ◽  
pp. 1501-1513 ◽  
Author(s):  
Jakob Engman ◽  
Aurel Negrea ◽  
Sara Sigurlásdóttir ◽  
Miriam Geörg ◽  
Jens Eriksson ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Posttranslational Modifications ◽  
Human Cells ◽  
Bacterial Attachment ◽  
Polynucleotide Phosphorylase ◽  
Gene Encoding ◽  
Content Type ◽  
Type Iv ◽  
Transcriptional Changes

Neisseria meningitidisautoaggregation is an important step during attachment to human cells. Aggregation is mediated by type IV pili and can be modulated by accessory pilus proteins, such as PilX, and posttranslational modifications of the major pilus subunit PilE. The mechanisms underlying the regulation of aggregation remain poorly characterized. Polynucleotide phosphorylase (PNPase) is a 3′–5′ exonuclease that is involved in RNA turnover and the regulation of small RNAs. In this study, we biochemically confirm that NMC0710 is theN. meningitidisPNPase, and we characterize its role inN. meningitidispathogenesis. We show that deletion of the gene encoding PNPase leads to hyperaggregation and increased adhesion to epithelial cells. The aggregation induced was found to be dependent on pili and to be mediated by excessive pilus bundling. PNPase expression was induced following bacterial attachment to human cells. Deletion of PNPase led to global transcriptional changes and the differential regulation of 469 genes. We also demonstrate that PNPase is required for full virulence in anin vivomodel ofN. meningitidisinfection. The present study shows that PNPase negatively affects aggregation, adhesion, and virulence inN. meningitidis.

scholarly journals Oxygen depletion and nitric oxide stimulate type IV MSHA pilus retraction in Vibrio cholerae via activation of the phosphodiesterase CdpA

2021 ◽  
Author(s):  
Hannah Q Hughes ◽  
Kyle A Floyd ◽  
Sajjad Hossain ◽  
Sweta Anantharaman ◽  
David T Kysela ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Bacterial Species ◽  
Bacterial Pathogen ◽  
Dna Uptake ◽  
Dynamic Activity ◽  
Regulatory Pathways ◽  
Type Iv ◽  
Microaerobic Conditions

Bacteria use surface appendages called type IV pili to perform diverse activities including DNA uptake, twitching motility, and attachment to surfaces. Dynamic extension and retraction of pili is often required for these activities, but the stimuli that regulate these dynamics remain poorly characterized. To study this question, we use the bacterial pathogen Vibrio cholerae, which uses mannose-sensitive hemagglutinin (MSHA) pili to attach to surfaces in aquatic environments as the first step in biofilm formation. Here, we find that V. cholerae cells retract MSHA pili and detach from a surface in microaerobic conditions. This response is dependent on the phosphodiesterase CdpA, which decreases intracellular levels of cyclic-di-GMP (c-di-GMP) under microaerobic conditions to induce MSHA pilus retraction. CdpA contains a putative NO-sensing NosP domain, and we demonstrate that nitric oxide (NO) is necessary and sufficient to stimulate CdpA-dependent detachment. Thus, we hypothesize that microaerobic conditions result in endogenous production of NO (or an NO-like molecule) in V. cholerae. Together, these results describe a regulatory pathway that allows V. cholerae to rapidly abort biofilm formation. More broadly, these results show how environmental cues can be integrated into the complex regulatory pathways that control pilus dynamic activity and attachment in bacterial species.

scholarly journals Cooperative Role for Tetraspanins in Adhesin-Mediated Attachment of Bacterial Species to Human Epithelial Cells

2011 ◽  
Vol 79 (6) ◽  
pp. 2241-2249 ◽  
Author(s):  
Luke R. Green ◽  
Peter N. Monk ◽  
Lynda J. Partridge ◽  
Paul Morris ◽  
Andrew R. Gorringe ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Neisseria Meningitidis ◽  
Bacterial Species ◽  
Small Interfering Rnas ◽  
Content Type ◽  
Type Iv ◽  
Bacterial Adhesins ◽  
Optimal Function ◽  
Specific Receptors ◽  
Multiple Species

ABSTRACTThe tetraspanins are a superfamily of transmembrane proteins with diverse functions and can form extended microdomains within the plasma membrane in conjunction with partner proteins, which probably includes receptors for bacterial adhesins.Neisseria meningitidis, the causative agent of meningococcal disease, attaches to host nasopharyngeal epithelial cells via type IV pili and opacity (Opa) proteins. We examined the role of tetraspanin function inNeisseria meningitidisadherence to epithelial cells. Tetraspanins CD9, CD63, and CD151 were expressed by HEC-1-B and DETROIT 562 cells. Coincubation of cells with antibodies against all three tetraspanin molecules used individually or in combination, with recombinant tetraspanin extracellular domains (EC2), or with small interfering RNAs (siRNAs) significantly reduced adherence ofNeisseria meningitidis. In contrast, recombinant CD81, a different tetraspanin, had no effect on meningococcal adherence. Antitetraspanin antibodies reduced the adherence to epithelial cells ofNeisseria meningitidisstrain derivatives expressing Opa and pili significantly more than isogenic strains lacking these determinants. Adherence to epithelial cells of strains ofStaphylococcus aureus,Neisseria lactamica,Escherichia coli, andStreptococcus pneumoniaewas also reduced by pretreatment of cells with tetraspanin antibodies and recombinant proteins. These data suggest that tetraspanins are required for optimal function of epithelial adhesion platforms containing specific receptors forNeisseria meningitidisand potentially for multiple species of bacteria.

scholarly journals Contribution of Type IV Pili to the Virulence of Aeromonas salmonicida subsp. salmonicida in Atlantic Salmon (Salmo salar L.)

2008 ◽  
Vol 76 (4) ◽  
pp. 1445-1455 ◽  
Author(s):  
Jessica M. Boyd ◽  
Andrew Dacanay ◽  
Leah C. Knickle ◽  
Ahmed Touhami ◽  
Laura L. Brown ◽  
...  
Keyword(s):  
Atlantic Salmon ◽  
Bacterial Pathogen ◽  
Aeromonas Salmonicida ◽  
Type Iv Pili ◽  
Wild Type ◽  
Gene Encoding ◽  
Force Microscopy ◽  
Type Iv ◽  
Atomic Force ◽  
Pilin Subunit

ABSTRACT Aeromonas salmonicida subsp. salmonicida, a bacterial pathogen of Atlantic salmon, has no visible pili, yet its genome contains genes for three type IV pilus systems. One system, Tap, is similar to the Pseudomonas aeruginosa Pil system, and a second, Flp, resembles the Actinobacillus actinomycetemcomitans Flp pilus, while the third has homology to the mannose-sensitive hemagglutinin pilus of Vibrio cholerae. The latter system is likely nonfunctional since eight genes, including the gene encoding the main pilin subunit, are deleted compared with the orthologous V. cholerae locus. The first two systems were characterized to investigate their expression and role in pathogenesis. The pili of A. salmonicida subsp. salmonicida were imaged using atomic force microscopy and Tap- and Flp-overexpressing strains. The Tap pili appeared to be polar, while the Flp pili appeared to be peritrichous. Strains deficient in tap and/or flp were used in live bacterial challenges of Atlantic salmon, which showed that the Tap pilus made a moderate contribution to virulence, while the Flp pilus made little or no contribution. Delivery of the tap mutant by immersion resulted in reduced cumulative morbidity compared with the cumulative morbidity observed with the wild-type strain; however, delivery by intraperitoneal injection resulted in cumulative morbidity similar to that of the wild type. Unlike the pili of other piliated bacterial pathogens, A. salmonicida subsp. salmonicida type IV pili are not absolutely required for virulence in Atlantic salmon. Significant differences in the behavior of the two mutant strains indicated that the two pilus systems are not redundant.

Phylogeny Characterization of Seb Gene Encoding Enterotoxins in Staphylococcus aureus Isolated from Raw Milk and Cheese

2019 ◽  
Vol 9 (o3) ◽  
Author(s):  
Fatima N. Aziz ◽  
Laith Abdul Hassan Mohammed-Jawad
Keyword(s):  
Staphylococcus Aureus ◽  
Food Poisoning ◽  
Raw Milk ◽  
Staphylococcal Enterotoxin B ◽  
Human Pathogen ◽  
Conventional Pcr ◽  
Biochemical Tests ◽  
Specific Primers ◽  
Gene Encoding

Food poisoning due to the bacteria is a big global problem in economically and human's health. This problem refers to an illness which is due to infection or the toxin exists in nature and the food that use. Milk is considered a nutritious food because it contains proteins and vitamins. The aim of this study is to detect and phylogeny characterization of staphylococcal enterotoxin B gene (Seb). A total of 200 milk and cheese samples were screened. One hundred ten isolates of Staphylococcus aureus pre-confirmed using selective and differential media with biochemical tests. Genomic DNA was extracted from the isolates and the SEB gene detects using conventional PCR with specific primers. Three staphylococcus aureus isolates were found to be positive for Seb gene using PCR and confirmed by sequencing. Sequence homology showed variety range of identity starting from (100% to 38%). Phylogenetic tree analyses show that samples (6 and 5) are correlated with S. epidermidis. This study discovered that isolates (A6-RLQ and A5-RLQ) are significantly clustered in a group with non- human pathogen Staphylococcus agnetis.

scholarly journals Legionella pneumophila DotU and IcmF Are Required for Stability of the Dot/Icm Complex

2004 ◽  
Vol 72 (10) ◽  
pp. 5983-5992 ◽  
Author(s):  
Jessica A. Sexton ◽  
Jennifer L. Miller ◽  
Aki Yoneda ◽  
Thomas E. Kehl-Fie ◽  
Joseph P. Vogel
Keyword(s):  
Cell Surface ◽  
Legionella Pneumophila ◽  
Bacterial Species ◽  
Wide Distribution ◽  
Host Cells ◽  
Growth Defect ◽  
Intracellular Growth ◽  
Homologous Proteins ◽  
Type Iv ◽  
Cell Surface Structure

ABSTRACT Legionella pneumophila utilizes a type IV secretion system (T4SS) encoded by 26 dot/icm genes to replicate inside host cells and cause disease. In contrast to all other L. pneumophila dot/icm genes, dotU and icmF have homologs in a wide variety of gram-negative bacteria, none of which possess a T4SS. Instead, dotU and icmF orthologs are linked to a locus encoding a conserved cluster of proteins designated IcmF-associated homologous proteins, which has been proposed to constitute a novel cell surface structure. We show here that dotU is partially required for L. pneumophila intracellular growth, similar to the known requirement for icmF. In addition, we show that dotU and icmF are necessary for optimal plasmid transfer and sodium sensitivity, two additional phenotypes associated with a functional Dot/Icm complex. We found that these effects are due to the destabilization of the T4SS at the transition into the stationary phase, the point at which L. pneumophila becomes virulent. Specifically, three Dot proteins (DotH, DotG, and DotF) exhibit decreased stability in a ΔdotU ΔicmF strain. Furthermore, overexpression of just one of these proteins, DotH, is sufficient to suppress the intracellular growth defect of the ΔdotU ΔicmF mutant. This suggests a model where the DotU and IcmF proteins serve to prevent DotH degradation and therefore function to stabilize the L. pneumophila T4SS. Due to their wide distribution among bacterial species and their genetic linkage to known or predicted cell surface structures, we propose that this function in complex stabilization may be broadly conserved.

scholarly journals Colonization of dermal arterioles by Neisseria meningitidis provides a safe haven from neutrophils

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Valeria Manriquez ◽  
Pierre Nivoit ◽  
Tomas Urbina ◽  
Hebert Echenique-Rivera ◽  
Keira Melican ◽  
...  
Keyword(s):  
Neisseria Meningitidis ◽  
Inflammatory Infiltrate ◽  
Immune Escape ◽  
Systemic Disease ◽  
Neutrophil Recruitment ◽  
Vascular Damage ◽  
Bacterial Burden ◽  
Human Pathogen ◽  
Humanized Mouse ◽  
Humanized Mouse Model

AbstractThe human pathogen Neisseria meningitidis can cause meningitis and fatal systemic disease. The bacteria colonize blood vessels and rapidly cause vascular damage, despite a neutrophil-rich inflammatory infiltrate. Here, we use a humanized mouse model to show that vascular colonization leads to the recruitment of neutrophils, which partially reduce bacterial burden and vascular damage. This partial effect is due to the ability of bacteria to colonize capillaries, venules and arterioles, as observed in human samples. In venules, potent neutrophil recruitment allows efficient bacterial phagocytosis. In contrast, in infected capillaries and arterioles, adhesion molecules such as E-Selectin are not expressed on the endothelium, and intravascular neutrophil recruitment is minimal. Our results indicate that the colonization of capillaries and arterioles by N. meningitidis creates an intravascular niche that precludes the action of neutrophils, resulting in immune escape and progression of the infection.

Sign in / Sign up

Export Citation Format

Share Document