scholarly journals Two Zinc Uptake Systems Contribute to the Full Virulence of Listeria monocytogenes during GrowthIn VitroandIn Vivo

2011 ◽  
Vol 80 (1) ◽  
pp. 14-21 ◽  
Author(s):  
David Corbett ◽  
Jiahui Wang ◽  
Stephanie Schuler ◽  
Gloria Lopez-Castejon ◽  
Sarah Glenn ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Zinc Uptake ◽  
Detectable Effect ◽  
Intracellular Growth ◽  
Content Type ◽  
Zinc Sensing ◽  
Identification And Characterization ◽  
Cell Deletion

ABSTRACTWe report here the identification and characterization of two zinc uptake systems, ZurAM and ZinABC, in the intracellular pathogenListeria monocytogenes. Transcription of both operons was zinc responsive and regulated by the zinc-sensing repressor Zur. Deletion of eitherzurAMorzinAhad no detectable effect on growth in defined media, but a doublezurAM zinAmutant was unable to grow in the absence of zinc supplementation. Deletion ofzinAhad no detectable effect on intracellular growth in HeLa epithelial cells. In contrast, growth of thezurAMmutant was significantly impaired in these cells, indicating the importance of the ZurAM system during intracellular growth. Notably, the deletion of bothzinAandzurAMseverely attenuated intracellular growth, with the double mutant being defective in actin-based motility and unable to spread from cell to cell. Deletion of eitherzurAMorzinAhad a significant effect on virulence in an oral mouse model, indicating that both zinc uptake systems are importantin vivoand establishing the importance of zinc acquisition during infection byL. monocytogenes. The presence of two zinc uptake systems may offer a mechanism by whichL. monocytogenescan respond to zinc deficiency within a variety of environments and during different stages of infection, with each system making distinct contributions under different stress conditions.

scholarly journals Characterization of Intracellular Growth RegulatoricgRby Utilizing Transcriptomics To Identify Mediators of Pathogenesis in Shigella flexneri

2013 ◽  
Vol 81 (9) ◽  
pp. 3068-3076 ◽  
Author(s):  
Carolyn R. Morris ◽  
Christen L. Grassel ◽  
Julia C. Redman ◽  
Jason W. Sahl ◽  
Eileen M. Barry ◽  
...  
Keyword(s):  
High Throughput ◽  
High Throughput Sequencing ◽  
Diarrheal Disease ◽  
Intracellular Growth ◽  
Bioinformatics Analyses ◽  
Content Type ◽  
Regulatory Pathways

ABSTRACTShigellaspecies Gram-negative bacteria which cause a diarrheal disease, known as shigellosis, by invading and destroying the colonic mucosa and inducing a robust inflammatory response. With no vaccine available, shigellosis annually kills over 600,000 children in developing countries. This study demonstrates the utility of combining high-throughput bioinformatic methods within vitroandin vivoassays to provide new insights into pathogenesis. Comparisons ofin vivoandin vitrogene expression identified genes associated with intracellular growth. Additional bioinformatics analyses identified genes that are present inS. flexneriisolates but not in the three otherShigellaspecies. Comparison of these two analyses revealed nine genes that are differentially expressed during invasion and that are specific toS. flexneri. One gene, a DeoR family transcriptional regulator with decreased expression during invasion, was further characterized and is now designatedicgR, forintracellulargrowthregulator. Deletion oficgRcaused no difference in growthin vitrobut resulted in increased intracellular replication in HCT-8 cells. Furtherin vitroandin vivostudies using high-throughput sequencing of RNA transcripts (RNA-seq) of an isogenic ΔicgRmutant identified 34 genes that were upregulated under both growth conditions. This combined informatics and functional approach has allowed the characterization of a gene and pathway previously unknown inShigellapathogenesis and provides a framework for further identification of novel virulence factors and regulatory pathways.

scholarly journals Identification and Characterization of UndAHRCR-6, an Outer Membrane Endecahemec-Type Cytochrome of Shewanella sp. Strain HRCR-6

2011 ◽  
Vol 77 (15) ◽  
pp. 5521-5523 ◽  
Author(s):  
Liang Shi ◽  
Sara M. Belchik ◽  
Zheming Wang ◽  
David W. Kennedy ◽  
Alice C. Dohnalkova ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Functional Role ◽  
Content Type ◽  
Reduction Of Iron ◽  
Identification And Characterization

ABSTRACTUndAHRCR-6was identified from the metal-reducing bacteriumShewanellasp. strain HRCR-6. Bothin vivoandin vitrocharacterization results indicate that UndAHRCR-6is an outer membrane endecahemec-type cytochrome and probably has a key functional role in the extracellular reduction of iron [Fe(III)] oxides and uranium [U(VI)] byShewanellasp. HRCR-6.

scholarly journals The thermostable 4,6-α-glucanotransferase of Bacillus coagulans DSM 1 synthesizes isomaltooligosaccharides

Amylase ◽  
2021 ◽  
Vol 5 (1) ◽  
pp. 13-22
Author(s):  
Gang Xiang ◽  
Piet L. Buwalda ◽  
Marc J.E.C van der Maarel ◽  
Hans Leemhuis
Keyword(s):  
Bacillus Coagulans ◽  
Glycoside Hydrolase Family ◽  
Rat Intestine ◽  
Glycaemic Response ◽  
Food Ingredient ◽  
Starch Conversion ◽  
Identification And Characterization ◽  
Hydrolase Family

Abstract The 4,6-α-glucanotransferases of the glycoside hydrolase family 70 can convert starch into isomaltooligosaccharides (IMOs). However, no thermostable 4,6-α-glucanotransferases have been reported to date, limiting their applicability in the starch conversion industry. Here we report the identification and characterization of a thermostable 4,6-α-glucanotransferase from Bacillus coagulans DSM 1. The gene was cloned and the recombinant protein, called BcGtfC, was produced in Escherichia coli. BcGtfC is stable up to 66 °C in the presence of substrate. It converts debranched starch into an IMO product with a high percentage of α-1,6-glycosidic linkages and a relatively high molecular weight compared to commercially available IMOs. Importantly, the product is only partly and very slowly digested by rat intestine powder, suggesting that the IMO will provide a low glycaemic response in vivo when applied as food ingredient. Thus, BcGtfC is a thermostable 4,6-α-glucanotransferase suitable for the industrial production of slowly digestible IMOs from starch.

scholarly journals Physiological and Transcriptional Characterization of Persistent and Nonpersistent Listeria monocytogenes Isolates

2011 ◽  
Vol 77 (18) ◽  
pp. 6559-6569 ◽  
Author(s):  
Edward M. Fox ◽  
Nola Leonard ◽  
Kieran Jordan
Keyword(s):  
Listeria Monocytogenes ◽  
Antimicrobial Agents ◽  
Cetylpyridinium Chloride ◽  
Phenotype Microarray ◽  
Content Type ◽  
Benzethonium Chloride ◽  
Transcriptomic Sequencing ◽  
Ammonium Compounds ◽  
Compare Gene Expression

ABSTRACTThis study aimed to characterize physiological differences between persistent and presumed nonpersistentListeria monocytogenesstrains isolated at processing facilities and to investigate the molecular basis for this by transcriptomic sequencing. Full metabolic profiles of two strains, one persistent and one nonpersistent, were initially screened using Biolog's Phenotype MicroArray (PM) technology. Based on these results, in which major differences from selected antimicrobial agents were detected, another persistent strain and two nonpersistent strains were characterized using two antimicrobial PMs. Resistance to quaternary ammonium compounds (QACs) was shown to be higher among persistent strains. Growth of persistent and nonpersistent strains in various concentrations of the QACs benzethonium chloride (BZT) and cetylpyridinium chloride (CPC) was determined. Transcriptomic sequencing of a persistent and a presumed nonpersistent strain was performed to compare gene expression among these strains in the presence and absence of BZT. Two strains, designated “frequent persisters” because they were the most frequently isolated at the processing facility, showed overall higher resistance to QACs. Transcriptome analysis showed that BZT induced a complex peptidoglycan (PG) biosynthesis response, which may play a key role in BZT resistance. Comparison of persistent and nonpersistent strains indicated that transcription of many genes was upregulated among persistent strains. This included three gene operons:pdu,cob-cbi, andeut. These genes may play a role in the persistence ofL. monocytogenesoutside the human host.

scholarly journals Identification and Characterization of a Halotolerant, Cold-Active Marine Endo-β-1,4-Glucanase by Using Functional Metagenomics of Seaweed-Associated Microbiota

2014 ◽  
Vol 80 (16) ◽  
pp. 4958-4967 ◽  
Author(s):  
Marjolaine Martin ◽  
Sophie Biver ◽  
Sébastien Steels ◽  
Tristan Barbeyron ◽  
Murielle Jam ◽  
...  
Keyword(s):  
Metagenomic Library ◽  
Functional Screening ◽  
Sample Collection ◽  
Prolonged Incubation ◽  
Content Type ◽  
Cold Active ◽  
Esterase Loci ◽  
Collection Period ◽  
Identification And Characterization

ABSTRACTA metagenomic library was constructed from microorganisms associated with the brown algaAscophyllum nodosum. Functional screening of this library revealed 13 novel putative esterase loci and two glycoside hydrolase loci. Sequence and gene cluster analysis showed the wide diversity of the identified enzymes and gave an idea of the microbial populations present during the sample collection period. Lastly, an endo-β-1,4-glucanase having less than 50% identity to sequences of known cellulases was purified and partially characterized, showing activity at low temperature and after prolonged incubation in concentrated salt solutions.

scholarly journals Identification and Characterization of Di- and Tripeptide Transporter DtpT of Listeria monocytogenes EGD-e

2005 ◽  
Vol 71 (10) ◽  
pp. 5771-5778 ◽  
Author(s):  
Jeroen A. Wouters ◽  
Torsten Hain ◽  
Ajub Darji ◽  
Eric Hüfner ◽  
Henrike Wemekamp-Kamphuis ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Opportunistic Infections ◽  
Essential Amino Acids ◽  
Defined Medium ◽  
Infection Model ◽  
Intracellular Pathogen ◽  
Mouse Infection Model ◽  
Stress Protection ◽  
Identification And Characterization

ABSTRACT Listeria monocytogenes is a gram-positive intracellular pathogen responsible for opportunistic infections in humans and animals. Here we identified and characterized the dtpT gene (lmo0555) of L. monocytogenes EGD-e, encoding the di- and tripeptide transporter, and assessed its role in growth under various environmental conditions as well as in the virulence of L. monocytogenes. Uptake of the dipeptide Pro-[14C]Ala was mediated by the DtpT transporter and was abrogated in a ΔdtpT isogenic deletion mutant. The DtpT transporter was shown to be required for growth when the essential amino acids leucine and valine were supplied as peptides. The protective effect of glycine- and proline-containing peptides during growth in defined medium containing 3% NaCl was noted only in L. monocytogenes EGD-e, not in the ΔdtpT mutant strain, indicating that the DtpT transporter is involved in salt stress protection. Infection studies showed that DtpT contributes to pathogenesis in a mouse infection model but has no role in bacterial growth following infection of J774 macrophages. These studies reveal that DptT may contribute to the virulence of L. monocytogenes.

scholarly journals The 8-Pyrrole-Benzothiazinones Are Noncovalent Inhibitors of DprE1 from Mycobacterium tuberculosis

2015 ◽  
Vol 59 (8) ◽  
pp. 4446-4452 ◽  
Author(s):  
Vadim Makarov ◽  
João Neres ◽  
Ruben C. Hartkoorn ◽  
Olga B. Ryabova ◽  
Elena Kazakova ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Nitro Group ◽  
Covalent Bond ◽  
Antimycobacterial Activity ◽  
Content Type ◽  
Sar Studies ◽  
Covalent Bond Formation

ABSTRACT8-Nitro-benzothiazinones (BTZs), such as BTZ043 and PBTZ169, inhibit decaprenylphosphoryl-β-d-ribose 2′-oxidase (DprE1) and display nanomolar bactericidal activity againstMycobacterium tuberculosisin vitro. Structure-activity relationship (SAR) studies revealed the 8-nitro group of the BTZ scaffold to be crucial for the mechanism of action, which involves formation of a semimercaptal bond with Cys387 in the active site of DprE1. To date, substitution of the 8-nitro group has led to extensive loss of antimycobacterial activity. Here, we report the synthesis and characterization of the pyrrole-benzothiazinones PyrBTZ01 and PyrBTZ02, non-nitro-benzothiazinones that retain significant antimycobacterial activity, with MICs of 0.16 μg/ml againstM. tuberculosis. These compounds inhibit DprE1 with 50% inhibitory concentration (IC50) values of <8 μM and present favorablein vitroabsorption-distribution-metabolism-excretion/toxicity (ADME/T) andin vivopharmacokinetic profiles. The most promising compound, PyrBTZ01, did not show efficacy in a mouse model of acute tuberculosis, suggesting that BTZ-mediated killing through DprE1 inhibition requires a combination of both covalent bond formation and compound potency.

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