scholarly journals IHF regulates host colonization factors in the bee gut symbiont Frischella perrara

2021 ◽  
Author(s):  
K. Schmidt ◽  
S. Leopold-Messer ◽  
O. Emery ◽  
Y. El-Chazli ◽  
T. Steiner ◽  
...  
Keyword(s):  
Point Mutations ◽  
Biosynthetic Gene Cluster ◽  
Integration Host Factor ◽  
Secretion Systems ◽  
Genetic Determinants ◽  
Host Colonization ◽  
Individual Gene ◽  
Gut Colonization ◽  
Genes Encoding ◽  
Colonization Factors

AbstractGut bacteria colonize specific niches in the digestive tract of animals. Yet, the genetic basis of these associations often remains elusive. The gut symbiont Frischella perrara colonizes the anterior hindgut of honey bees, where it causes a characteristic immune response leading to the formation of the scab phenotype. Genetic determinants required for the establishment of this specific association are currently unknown. Here, we independently isolated three point mutations in the two genes encoding the DNA-binding protein integration host factor (IHF). The mutations resulted in the formation of larger colonies on agar plates and the absence of an aryl polyene metabolite conferring the yellow color to colonies of F. perrara. Inoculation of microbiota-free bees with one of these mutants drastically decreased gut colonization of F. perrara and abolished scab development. Using RNAseq we show that IHF affects the expression of potential colonization factors, including a colibactin biosynthetic gene cluster, two Type 6 secretion systems, pili genes, and the aryl polyene biosynthesis pathway. Individual gene deletions of these components revealed different colonization defects indicating that these genetic determinants of F. perrara have distinct roles in the interaction with the host. IHF is conserved across many bacteria and may regulate host colonization also in other animal symbionts.

scholarly journals RegA, an AraC-Like Protein, Is a Global Transcriptional Regulator That Controls Virulence Gene Expression in Citrobacter rodentium

2008 ◽  
Vol 76 (11) ◽  
pp. 5247-5256 ◽  
Author(s):  
Emily Hart ◽  
Ji Yang ◽  
Marija Tauschek ◽  
Michelle Kelly ◽  
Matthew J. Wakefield ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Virulence Gene ◽  
Virulence Determinants ◽  
Intestinal Colonization ◽  
Citrobacter Rodentium ◽  
Promoter Regions ◽  
Reading Frame ◽  
Virulence Gene Expression ◽  
Genes Encoding ◽  
Colonization Factors

ABSTRACT Citrobacter rodentium is an attaching and effacing pathogen which causes transmissible colonic hyperplasia in mice. Infection with C. rodentium serves as a model for infection of humans with enteropathogenic and enterohemorrhagic Escherichia coli. To identify novel colonization factors of C. rodentium, we screened a signature-tagged mutant library of C. rodentium in mice. One noncolonizing mutant had a single transposon insertion in an open reading frame (ORF) which we designated regA because of its homology to genes encoding members of the AraC family of transcriptional regulators. Deletion of regA in C. rodentium resulted in markedly reduced colonization of the mouse intestine. Examination of lacZ transcriptional fusions using promoter regions of known and putative virulence-associated genes of C. rodentium revealed that RegA strongly stimulated transcription of two newly identified genes located close to regA, which we designated adcA and kfcC. The cloned adcA gene conferred autoaggregation and adherence to mammalian cells to E. coli strain DH5α, and a kfc mutation led to a reduction in the duration of intestinal colonization, but the kfc mutant was far less attenuated than the regA mutant. These results indicated that other genes of C. rodentium whose expression required activation by RegA were required for colonization. Microarray analysis revealed a number of RegA-regulated ORFs encoding proteins homologous to known colonization factors. Transcription of these putative virulence determinants was activated by RegA only in the presence of sodium bicarbonate. Taken together, these results show that RegA is a global regulator of virulence in C. rodentium which activates factors that are required for intestinal colonization.

scholarly journals Genetic determinants of Pseudomonas aeruginosa biofilm establishment

Microbiology ◽  
2010 ◽  
Vol 156 (2) ◽  
pp. 431-441 ◽  
Author(s):  
Mathias Müsken ◽  
Stefano Di Fiore ◽  
Andreas Dötsch ◽  
Rainer Fischer ◽  
Susanne Häussler
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Laser Scanning ◽  
Growth Conditions ◽  
Confocal Laser Scanning Microscope ◽  
Confocal Laser ◽  
Repair System ◽  
Ph Homeostasis ◽  
Genetic Determinants ◽  
Complex Process ◽  
Genes Encoding

The establishment of bacterial biofilms on surfaces is a complex process that requires various factors for each consecutive developmental step. Here we report the screening of the comprehensive Harvard Pseudomonas aeruginosa PA14 mutant library for mutants exhibiting an altered biofilm phenotype. We analysed the capability of all mutants to form biofilms at the bottom of a 96-well plate by the use of an automated confocal laser-scanning microscope and found 394 and 285 genetic determinants of reduced and enhanced biofilm production, respectively. Overall, 67 % of the identified mutants were affected within genes encoding hypothetical proteins, indicating that novel developmental pathways are likely to be dissected in the future. Nevertheless, a common theme that emerged from the analysis of the genes with a predicted function is that the establishment of a biofilm requires regulatory components that are involved in survival under microaerophilic growth conditions, arginine metabolism, alkyl-quinolone signalling, pH homeostasis and the DNA repair system.

scholarly journals The Primary Causes of Muscle Dysfunction Associated with the Point Mutations in Tpm3.12; Conformational Analysis of Mutant Proteins as a Tool for Classification of Myopathies

2018 ◽  
Vol 19 (12) ◽  
pp. 3975 ◽  
Author(s):  
Yurii Borovikov ◽  
Olga Karpicheva ◽  
Armen Simonyan ◽  
Stanislava Avrova ◽  
Elena Rogozovets ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Molecular Mechanisms ◽  
Fiber Type ◽  
Point Mutations ◽  
Nemaline Myopathy ◽  
Muscle Dysfunction ◽  
Thin Filaments ◽  
Mutant Proteins ◽  
Strong Binding ◽  
Genes Encoding

Point mutations in genes encoding isoforms of skeletal muscle tropomyosin may cause nemaline myopathy, cap myopathy (Cap), congenital fiber-type disproportion (CFTD), and distal arthrogryposis. The molecular mechanisms of muscle dysfunction in these diseases remain unclear. We studied the effect of the E173A, R90P, E150A, and A155T myopathy-causing substitutions in γ-tropomyosin (Tpm3.12) on the position of tropomyosin in thin filaments, and the conformational state of actin monomers and myosin heads at different stages of the ATPase cycle using polarized fluorescence microscopy. The E173A, R90P, and E150A mutations produced abnormally large displacement of tropomyosin to the inner domains of actin and an increase in the number of myosin heads in strong-binding state at low and high Ca2+, which is characteristic of CFTD. On the contrary, the A155T mutation caused a decrease in the amount of such heads at high Ca2+ which is typical for mutations associated with Cap. An increase in the number of the myosin heads in strong-binding state at low Ca2+ was observed for all mutations associated with high Ca2+-sensitivity. Comparison between the typical conformational changes in mutant proteins associated with different myopathies observed with α-, β-, and γ-tropomyosins demonstrated the possibility of using such changes as tests for identifying the diseases.

scholarly journals Comparative Analysis of Genetic Determinants Encoding Cadmium, Arsenic, and Benzalkonium Chloride Resistance in Listeria monocytogenes of Human, Food, and Environmental Origin

2021 ◽  
Vol 11 ◽  
Author(s):  
Tereza Gelbicova ◽  
Martina Florianova ◽  
Lucie Hluchanova ◽  
Alžběta Kalova ◽  
Kristýna Korena ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Benzalkonium Chloride ◽  
Extensive Study ◽  
Whole Genome Sequencing Data ◽  
Production Environment ◽  
Sequencing Data ◽  
Genetic Determinants ◽  
Cadmium Resistance ◽  
Chloride Resistance ◽  
Genes Encoding

Environmental adaptation of Listeria monocytogenes is a complex process involving various mechanisms that can contribute to their survival in the environment, further spreading throughout the food chain and the development of listeriosis. The aim of this study was to analyze whole-genome sequencing data in a set of 270 strains of L. monocytogenes derived from human listeriosis cases and food and environmental sources in order to compare the prevalence and type of genetic determinants encoding cadmium, arsenic, and benzalkonium chloride resistance. Most of the detected genes of cadmium (27.8%), arsenic (15.6%), and benzalkonium chloride (7.0%) resistance were located on mobile genetic elements, even in phylogenetically distant lineages I and II, which indicates the possibility of their horizontal spread. Although no differences were found in the prevalence of these genes between human and food strains, they have been detected sporadically in strains from the environment. Regarding cadmium resistance genes, cadA1C1_Tn5422 predominated, especially in clonal complexes (CCs) 121, 8, and 3 strains. At the same time, qacH_Tn6188-encoding benzalkonium chloride resistance was most frequently detected in the genome of CC121 strains. Genes encoding arsenic resistance were detected mainly in strains CC2 (located on the chromosomal island LGI2) and CC9 (carried on Tn554). The results indicated a relationship between the spread of genes encoding resistance to cadmium, arsenic, and benzalkonium chloride in certain serotypes and CCs and showed the need for a more extensive study of L. monocytogenes strains to better understand their ability to adapt to the food production environment.

scholarly journals A family of T6SS antibacterial effectors related to L,D-transpeptidases targets the Peptidoglycan

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Stephanie Sibinelli de Sousa ◽  
Julia Takuno Hespanhol ◽  
Bruno Matsuyama ◽  
Stephane Mesnage ◽  
Gianlucca Nicastro ◽  
...  
Keyword(s):  
Cell Envelope ◽  
Point Mutations ◽  
Time Lapse ◽  
Secretion Systems ◽  
Bacterial Antagonism ◽  
New Family ◽  
Type Vi Secretion ◽  
Altered Cell ◽  
Bacterial Effectors ◽  
Insight Into

Type VI secretion systems (T6SSs) are contractile nanomachines widely used by bacteria to intoxicate competitors. Salmonella Typhimurium encodes a T6SS within the Salmonella pathogenicity island 6 (SPI-6) that is used during competition against species of the gut microbiota. We characterized a new SPI-6 T6SS antibacterial effector named Tlde1 (type VI L,D-transpeptidase effector 1). Tlde1 is toxic in target-cell periplasm and its toxicity is neutralized by co-expression with immunity protein Tldi1 (type VI L,D-transpeptidase immunity 1). Time-lapse microscopy revealed that intoxicated cells display altered cell division and lose cell envelope integrity. Bioinformatics analysis showed that Tlde1 is evolutionarily related to L,D-transpeptidases. Point mutations on conserved histidine121 and cysteine131 residues eliminated toxicity. Co-incubation of purified recombinant Tlde1 and peptidoglycan tetrapeptides showed that Tlde1 displays both L,D-carboxypeptidase activity by cleaving GM-tetrapeptides between meso-diaminopimelic acid3 and D-alanine4, and L,D-transpeptidase exchange activity by replacing D-alanine4 for a non-canonical D-amino acid. Tlde1 constitutes a new family of T6SS effectors widespread in Proteobacteria. This work increases our knowledge about the bacterial effectors used in interbacterial competitions and provides molecular insight into a new mechanism of bacterial antagonism.

scholarly journals From genomes to systems: the path with yeast

2006 ◽  
Vol 361 (1467) ◽  
pp. 477-482 ◽  
Author(s):  
Stephen G Oliver
Keyword(s):  
Eukaryotic Cell ◽  
Metabolic Control Analysis ◽  
Coarse Grained ◽  
Control Analysis ◽  
Individual Gene ◽  
Metabolic Systems ◽  
Genes Encoding ◽  
Balance Analysis ◽  
Definition Of ◽  
The Impact

Metabolic Control Analysis (MCA) is a conceptual and mathematical formalism that models the relative contributions of individual effectors in a pathway to both the flux through the pathway and the concentrations of individual intermediates within it. To exploit MCA in an initial Systems Biology analysis of the eukaryotic cell, two categories of experiments are required. In category 1 experiments, flux is changed and the impact on the levels of the direct and indirect products of gene action is measured. We have measured the impact of changing the flux on the transcriptome, proteome and metabolome of Saccharomyces cerevisiae . In this whole-cell analysis, flux equates to growth rate. In category 2 experiments, the levels of individual gene products are altered, and the impact on the flux is measured. We have used competition analyses between the complete set of heterozygous yeast deletion mutants to reveal genes encoding proteins with high flux control coefficients. These genes may be exploited, in a top-down analysis, to build a coarse-grained model of the eukaryotic cell, as exemplified by yeast. More detailed modelling requires that ‘natural’ biological systems be identified. The combination of flux balance analysis with both genetics and metabolomics in the definition of metabolic systems is discussed.

Formula-fed and Clostridium difficile infected neonatal piglets carry a highly diverse and abundant set of antimicrobial resistance genes

2020 ◽  
Author(s):  
Robert Pieper ◽  
Temesgen Dadi ◽  
Lukasz Grzeskowiak ◽  
Laura Pieper ◽  
Britta Siegmund ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Antimicrobial Resistance ◽  
Resistance Genes ◽  
Microbial Colonization ◽  
Metagenomic Data ◽  
Neonatal Piglets ◽  
Gut Colonization ◽  
Antimicrobial Resistance Genes ◽  
Antimicrobial Resistance Gene ◽  
Genes Encoding

Abstract Background: Clostridium difficile infection (CDI) is an increasing zoonotic health threat and has also been documented as a cause of enteritis outbreaks in neonatal pigs. Furthermore, CDI in neonatal piglets cause changes in microbial gut colonization. We hypothesized that an imbalanced microbial colonization in piglets with CDI could be associated with an altered abundance of antimicrobial resistance genes. Results: We analyzed fecal metagenomic data of lactating sows (S), their piglets during suckling (SP), the same piglets two weeks after weaning (WP), 5-day old artificially reared and formula-fed siblings (FP) and FP infected with C. difficile (FP-CD) for microbiota composition and antimicrobial resistance gene abundance. FP and FP-CD piglets had an immature-type microbiota and increased abundance of antimicrobial resistance genes. A co-occurrence of genes encoding for resistance against aminoglycosides (e.g. aph(3”)-lb, aph(6)-ld, ant(2”)-la), β-lactams (blaCTX-M, blaTEM), fluoroquinolones (pat(A) macrolides (mph(A)), sulfonamides (sul1, sul2), polypeptides (e.g. pmrB, pmrC, arnA, bac(A)) and tetracyclines (e.g. tet(A-D),) was observed. Conclusion: Increased abundance of antimicrobial resistance genes in formula feeding and concomitant CDI may be associated with therapeutic resistance later in life and warrant further studies.

scholarly journals Accelerated Electro-Fermentation of Acetoin in Escherichia coli by Identifying Physiological Limitations of the Electron Transfer Kinetics and the Central Metabolism

2020 ◽  
Vol 8 (11) ◽  
pp. 1843
Author(s):  
Sebastian Beblawy ◽  
Laura-Alina Philipp ◽  
Johannes Gescher
Keyword(s):  
Escherichia Coli ◽  
Electron Transfer ◽  
Point Mutations ◽  
Selective Adaptation ◽  
Space Time ◽  
Transport Chain ◽  
Whole Cell Biocatalyst ◽  
Genes Encoding ◽  
Space Time Yield ◽  
Respiratory Conditions

Anode-assisted fermentations offer the benefit of an anoxic fermentation routine that can be applied to produce end-products with an oxidation state independent from the substrate. The whole cell biocatalyst transfers the surplus of electrons to an electrode that can be used as a non-depletable electron acceptor. So far, anode-assisted fermentations were shown to provide high carbon efficiencies but low space-time yields. This study aimed at increasing space-time yields of an Escherichia coli-based anode-assisted fermentation of glucose to acetoin. The experiments build on an obligate respiratory strain, that was advanced using selective adaptation and targeted strain development. Several transfers under respiratory conditions led to point mutations in the pfl, aceF and rpoC gene. These mutations increased anoxic growth by three-fold. Furthermore, overexpression of genes encoding a synthetic electron transport chain to methylene blue increased the electron transfer rate by 2.45-fold. Overall, these measures and a medium optimization increased the space-time yield in an electrode-assisted fermentation by 3.6-fold.

scholarly journals Sugar-mediated regulation of a c-di-GMP phosphodiesterase in Vibrio cholerae

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Kyoo Heo ◽  
Young-Ha Park ◽  
Kyung-Ah Lee ◽  
Joonwon Kim ◽  
Hyeong-In Ham ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Biofilm Formation ◽  
Carbon Sources ◽  
Phosphotransferase System ◽  
Host Colonization ◽  
Host Immune Responses ◽  
Gut Colonization ◽  
Host Diet ◽  
Underlying Mechanisms ◽  
Cyclic Dinucleotide

AbstractBiofilm formation protects bacteria from stresses including antibiotics and host immune responses. Carbon sources can modulate biofilm formation and host colonization in Vibrio cholerae, but the underlying mechanisms remain unclear. Here, we show that EIIAGlc, a component of the phosphoenolpyruvate (PEP):carbohydrate phosphotransferase system (PTS), regulates the intracellular concentration of the cyclic dinucleotide c-di-GMP, and thus biofilm formation. The availability of preferred sugars such as glucose affects EIIAGlc phosphorylation state, which in turn modulates the interaction of EIIAGlc with a c-di-GMP phosphodiesterase (hereafter referred to as PdeS). In a Drosophila model of V. cholerae infection, sugars in the host diet regulate gut colonization in a manner dependent on the PdeS-EIIAGlc interaction. Our results shed light into the mechanisms by which some nutrients regulate biofilm formation and host colonization.

scholarly journals Frequency and expression of mutacin biosynthesis genes in isolates of Streptococcus mutans with different mutacin-producing phenotypes

2008 ◽  
Vol 57 (5) ◽  
pp. 626-635 ◽  
Author(s):  
Regianne Umeko Kamiya ◽  
José Francisco Höfling ◽  
Reginaldo Bruno Gonçalves
Keyword(s):  
Streptococcus Mutans ◽  
Staphylococcus Epidermidis ◽  
High Frequency ◽  
Phenotypic Diversity ◽  
Genetic Determinants ◽  
Rt Pcr ◽  
Expression Of Genes ◽  
Genes Encoding ◽  
Spearman Correlation Test ◽  
Expression Frequency

The aim of this study was to analyse the frequency and expression of biosynthesis genes in 47 Streptococcus mutans isolates with different mutacin-producing phenotypes. Detection of the frequency and expression of genes encoding mutacin types I, II, III and IV were carried out by PCR and semi-quantitative RT-PCR, respectively, using primers specific for each type of biosynthesis gene. In addition, a further eight genes encoding putative bacteriocins, designated bsm 283, bsm 299, bsm 423, bsm 1889c, bsm 1892c, bsm 1896, bsm 1906c and bsm 1914, were also screened. There was a high phenotypic diversity; some Streptococcus mutans isolates presented broad antimicrobial spectra against other Streptococcus mutans clinical isolates, including bacteria resistant to common antibiotics, as well as Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and Streptococcus pyogenes. The expression frequency of the bsm gene was higher than that of the previously characterized mutacins (I–IV). There was no positive correlation between the number of indicator strains inhibited (antimicrobial spectra) and the number of biosynthesis genes expressed (Spearman correlation test, r=−0.03, P>0.05). In conclusion, the high diversity of mutacin-producing phenotypes, associated with high frequency of expression of the biosynthesis genes screened, reveals a broad repertoire of genetic determinants encoding antimicrobial peptides that can act in different combinations.

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