RpoN and the Nps and Npa two-component regulatory system control pilE transcription in commensal Neisseria.
Ontology highlight
ABSTRACT:
SUBMITTER: Rendon MA
PROVIDER: S-EPMC6528607 | biostudies-literature |
REPOSITORIES: biostudies-literature
Similar Datasets
Project description:Human-adapted Neisseria includes two pathogens, Neisseria gonorrhoeae and Neisseria meningitidis, and at least 13 species of commensals that colonize many of the same niches as the pathogens. The Type IV pilus plays an important role in the biology of pathogenic Neisseria. In these species, Sigma factor RpoD (?(70)), Integration Host Factor, and repressors RegF and CrgA regulate transcription of pilE, the gene encoding the pilus structural subunit. The Type IV pilus is also a strictly conserved trait in commensal Neisseria. We present evidence that a different mechanism regulates pilE transcription in commensals. Using Neisseria elongata as a model, we show that Sigma factor RpoN (?(54)), Integration Host Factor, and an activator we name Npa regulate pilE transcription. Taken in context with previous reports, our findings indicate pilE regulation switched from an RpoN- to an RpoD-dependent mechanism as pathogenic Neisseria diverged from commensals during evolution. Our findings have implications for the timing of Tfp expression and Tfp-mediated host cell interactions in these two groups of bacteria.
| S-EPMC4474139 | biostudies-literature
Project description:Initially, pilE transcription in Neisseria gonorrhoeae appeared to be complicated, yet it was eventually simplified into a model where integration host factor activates a single -35/?-10 promoter. However, with the advent of high-throughput RNA sequencing, numerous small pil-specific RNAs (sense as well as antisense) have been identified at the pilE locus as well as at various pilS loci. Using a combination of in vitro transcription, site-directed mutagenesis, Northern analysis and quantitative reverse transcriptase PCR (qRT-PCR) analysis, we have identified three additional non-canonical promoter elements within the pilE gene; two are located within the midgene region (one sense and one antisense), with the third, an antisense promoter, located immediately downstream of the pilE ORF. Using strand-specific qRT-PCR analysis, an inverse correlation exists between the level of antisense expression and the amount of sense message. By their nature, promoter sequences tend to be AT-rich. In Escherichia coli, the small DNA-binding protein H-NS binds to AT-rich sequences and inhibits intragenic transcription. In N. gonorrhoeae hns mutants, pilE antisense transcription was increased twofold, with a concomitant decrease in sense transcript levels. However, most noticeably in these mutants, the absence of H-NS protein caused pilE/pilS recombination to increase dramatically when compared with WT values. Consequently, H-NS protein suppresses pilE intragenic transcription as well as antigenic variation through the pilE/pilS recombination system.
| S-EPMC6190205 | biostudies-literature
Project description:Outer membrane iron receptors are some of the major surface entities that are critical for meningococcal pathogenesis. The gene encoding the meningococcal hemoglobin receptor, HmbR, is both independently transcribed and transcriptionally linked to the upstream gene hemO, which encodes a heme oxygenase. The MisR/S two-component system was previously determined to regulate hmbR transcription, and its hemO and hmbR regulatory mechanisms were characterized further here. The expression of hemO and hmbR was downregulated in misR/S mutants under both iron-replete and iron-restricted conditions, and the downregulation could be reversed by complementation. No significant changes in expression of other iron receptors were detected, suggesting that the MisR/S system specifically regulates hmbR. When hemoglobin was the sole iron source, growth defects were detected in the mutants. Primer extension analysis identified a promoter upstream of the hemO-associated Correia element (CE) and another promoter at the proximal end of CE, and processed transcripts previously identified for other cotranscribed CEs were also detected, suggesting that there may be posttranscriptional regulation. MisR directly interacts with sequences upstream of the CE and upstream of the hmbR Fur binding site and thus independently regulates hemO and hmbR. Analysis of transcriptional reporters of hemO and hmbR further demonstrated the positive role of the MisR/S system and showed that the transcription of hmbR initiated from hemO was significantly reduced. A comparison of the effects of the misS mutation under iron-replete and iron-depleted conditions suggested that activation by the MisR/S system and iron-mediated repression by Fur act independently. Thus, the expression of hemO and hmbR is coordinately controlled by multiple independent regulatory mechanisms, including the MisR/S two-component system.
| S-EPMC2825934 | biostudies-literature
Project description:The mucosa is colonized with commensal Neisseria. Some of these niches are sites of infection for the STD pathogen Neisseria gonorrhoeae (Ngo). Given the antagonistic behavior of commensal bacteria toward their pathogenic relatives, we hypothesized that commensal Neisseria may negatively affect Ngo colonization. Here, we report that commensal species of Neisseria kill Ngo through a mechanism based on genetic competence and DNA methylation state. Specifically, commensal-triggered killing occurs when the pathogen takes up commensal DNA containing a methylation pattern that it does not recognize. Indeed, any DNA will kill Ngo if it can enter the cell, is differentially methylated, and has homology to the pathogen genome. Consistent with these findings, commensal Neisseria elongata accelerates Ngo clearance from the mouse in a DNA-uptake-dependent manner. Collectively, we propose that commensal Neisseria antagonizes Ngo infection through a DNA-mediated mechanism and that DNA is a potential microbicide against this highly drug-resistant pathogen.
| S-EPMC6728082 | biostudies-literature
Project description:Two-component regulatory systems are involved in processes important for bacterial pathogenesis. The proposed misR/misS (or phoP/phoQ) system is one of four two-component systems of the obligate human pathogen Neisseria meningitidis. Inactivation of this system results in loss of phosphorylation of the lipooligosaccharide inner core and causes attenuation in a mouse model of meningococcal infection. MisR and the cytoplasmic domain of MisS were purified as His6 and maltose binding protein fusion proteins, respectively. The MisS fusion was shown to be autophosphorylated in the presence of ATP, and the phosphoryl group was subsequently transferred to MisR. The phosphotransfer reaction was halted with a MisR/D52A mutation, while a MisS/H246A mutation prevented autophosphorylation. Specific interaction of phosphorylated MisR (MisR approximately P) and MisR with the misR promoter was demonstrated by gel mobility shift assays, where MisR approximately P exhibited higher affinity than did the nonphosphorylated protein. The transcriptional start site of the misRS operon was mapped, and DNase I protection assays revealed that MisR interacted with a 15-bp region upstream of the transcriptional start site that shared no similarity to binding motifs of other two-component systems. Transcriptional reporter studies suggested that MisR phosphorylation is critical for the autoinduction of the misRS operon. Limited Mg2+ concentration failed to induce expression of the misRS operon, which is the only operon now proven to be under the direct control of the MisRS two-component system. Thus, these results indicate that the meningococcal MisRS system constitutes a functional signal transduction circuit and that both components are critical in the autoregulation of their expression.
| S-EPMC1539957 | biostudies-literature
Project description:Part of a study to characterise the two component regulatory system yehUT of Salmonella enterica serovar Salmonella Typhi and Typhimurium. 24 Samples examined, 12 of strain Salmonella Typhi BRD948 and 12 of strain Salmonella Typhimurium ST4/74.
2013-09-17 | E-GEOD-50825 | biostudies-arrayexpress
Project description:Two Neisseria gonorrhoeae isolates from Seattle and two isolates from Uruguay were resistant to erythromycin (MIC, 4 to 16 microg/ml) and had reduced susceptibility to azithromycin (MIC, 1 to 4 microg/ml) due to the presence of the self-mobile rRNA methylase gene(s) ermF or ermB and ermF. The two Seattle isolates and one isolate from Uruguay were multiresistant, carrying either the 25.2-MDa tetM-containing plasmid (Seattle) or a beta-lactamase plasmid (Uruguay). Sixteen commensal Neisseria isolates (10 Neisseria perflava-N. sicca, 2 N. flava, and 4 N. mucosa) for which erythromycin MICs were 4 to 16 microg/ml were shown to carry one or more known rRNA methylase genes, including ermB, ermC, and/or ermF. Many of these isolates also were multiresistant and carried the tetM gene. This is the first time that a complete transposon or a complete conjugative transposon carrying an antibiotic resistance gene has been described for the genus Neisseria.
| S-EPMC89280 | biostudies-literature
Project description:Xiaguan Tuo Tea is largely consumed by the Chinese, but there is little research into the microbial diversity and component changes during the fermentation of this tea. In this study, we first used fluorescence in situ hybridization (FISH), next-generation sequencing (NGS) and chemical analysis methods to determine the microbial abundance and diversity and the chemical composition during fermentation. The FISH results showed that the total number of microorganisms ranges from 2.3×102 to 4.0×108 cells per gram of sample during fermentation and is mainly dominated by fungi. In the early fermentation stages, molds are dominant (0.6×102~2.8×106 cells/g, 0~35 d). However, in the late stages of fermentation, yeasts are dominant (3.6×104~9.6×106 cells/g, 35~56 d). The bacteria have little effect during the fermentation of tea (102~103 cells/g, <1% of fungus values). Of these fungi, A. niger (Aspergillus niger) and B. adeninivorans (Blastobotrys adeninivorans) are identified as the two most common strains, based on Next-generation Sequencing (NGS) analysis. Peak diversity in tea was observed at day 35 of fermentation (Shannon-Weaver index: 1.195857), and lower diversity was observed on days 6 and 56 of fermentation (Shannon-Weaver index 0.860589 and 1.119106, respectively). During the microbial fermentation, compared to the unfermented tea, the tea polyphenol content decreased by 54%, and the caffeine content increased by 59%. Theanine and free amino acid contents were reduced during fermentation by 81.1 and 92.85%, respectively.
| S-EPMC5819769 | biostudies-literature
Project description:Quinolone resistance is increasing in Neisseria meningitidis, with its prevalence in China being high (>70%), but its origin remains unknown. The aim of this study was to investigate the donors of mutation-harboring gyrA alleles in N. meningitidis A total of 198 N. meningitidis isolates and 293 commensal Neisseria isolates were collected between 2005 and 2018 in Shanghai, China. The MICs of ciprofloxacin were determined using the agar dilution method. The resistance-associated genes gyrA and parC were sequenced for all isolates, while a few isolates were sequenced on the Illumina platform. The prevalences of quinolone resistance in the N. meningitidis and commensal Neisseria isolates were 67.7% (134/198) and 99.3% (291/293), respectively. All 134 quinolone-resistant N. meningitidis isolates possessed mutations in T91 (n = 123) and/or D95 (n = 12) of GyrA, with 7 isolates also harboring ParC mutations and exhibiting higher MICs. Phylogenetic analysis of the gyrA sequence identified six clusters. Among the 71 mutation-harboring gyrA alleles found in 221 N. meningitidis isolates and genomes (n = 221), 12 alleles (n = 103, 46.6%) were included in the N. meningitidis cluster, while 20 alleles (n = 56) were included in the N. lactamica cluster, 27 alleles (n = 49) were included in the N. cinerea cluster, and 9 alleles (n = 10) were included in the N. subflava cluster. Genomic analyses identified the exact N. lactamica donors of seven mutation-harboring gyrA alleles (gyrA92, gyrA97, gyrA98, gyrA114, gyrA116, gyrA151, and gyrA230) and the N. subflava donor isolate of gyrA171, with the sizes of the recombinant fragments ranging from 634 to 7,499 bp. Transformation of gyrA fragments from these donor strains into a meningococcal isolate increased its ciprofloxacin MIC from 0.004 μg/ml to 0.125 or 0.19 μg/ml and to 0.5 μg/ml with further transformation of an additional ParC mutation. Over half of the quinolone-resistant N. meningitidis isolates acquired resistance by horizontal gene transfer from three commensal Neisseria species. Quinolone resistance in N. meningitidis increases in a stepwise manner.
| S-EPMC6985708 | biostudies-literature
Project description:Type VI Secretion Systems (T6SSs) are widespread in bacteria and can dictate the development and organisation of polymicrobial ecosystems by mediating contact dependent killing. In Neisseria species, including Neisseria cinerea a commensal of the human respiratory tract, interbacterial contacts are mediated by Type four pili (Tfp) which promote formation of aggregates and govern the spatial dynamics of growing Neisseria microcolonies. Here, we show that N. cinerea expresses a plasmid-encoded T6SS that is active and can limit growth of related pathogens. We explored the impact of Tfp on N. cinerea T6SS-dependent killing within a colony and show that pilus expression by a prey strain enhances susceptibility to T6SS compared to a non-piliated prey, by preventing segregation from a T6SS-wielding attacker. Our findings have important implications for understanding how spatial constraints during contact-dependent antagonism can shape the evolution of microbial communities.
| S-EPMC8263058 | biostudies-literature