The CRISPR/Cas system in <i>Neisseria meningitidis</i> affects bacterial adhesion to human nasopharyngeal epithelial cells

Heidrich, Nadja; Hagmann, Antony; Bauriedl, Saskia; Vogel, Jörg; Schoen, Christoph

doi:10.1080/15476286.2018.1486660

Cited by 17 publications

(17 citation statements)

References 29 publications

(47 reference statements)

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“…Given the phenotypes of the Δ cas9 mutant in adherence to and invasion of brain endothelial and vaginal epithelial cells, we expected to observe dysregulation of genes encoding for cell wall anchored proteins or for known or predicted GBS adhesins in the Δ cas9 mutant compared to WT COH1. However, very few genes in this category were found to be altered, similar to recently published transcriptomic analysis of cas9 -deficient strains in N. meningitidis (Heidrich et al, 2019), in which Cas9 was shown to affect adherence to epithelial cells indirectly, not by modulating expression of adhesins.…”

Section: Discussionsupporting

confidence: 84%

Cas9 Contributes to Group B Streptococcal Colonization and Disease

et al. 2019

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Group B Streptococcus (GBS) is a major opportunistic pathogen in certain adult populations, including pregnant women, and remains a leading etiologic agent of newborn disease. During pregnancy, GBS asymptomatically colonizes the vaginal tract of 20–30% of healthy women, but can be transmitted to the neonate in utero or during birth resulting in neonatal pneumonia, sepsis, meningitis, and subsequently 10–15% mortality regardless of antibiotic treatment. While various GBS virulence factors have been implicated in vaginal colonization and invasive disease, the regulation of many of these factors remains unclear. Recently, CRISPR-associated protein-9 (Cas9), an endonuclease known for its role in CRISPR/Cas immunity, has also been observed to modulate virulence in a number of bacterial pathogens. However, the role of Cas9 in GBS colonization and disease pathogenesis has not been well-studied. We performed allelic replacement of cas9 in GBS human clinical isolates of the hypervirulent sequence-type 17 strain lineage to generate isogenic Δ cas9 mutants. Compared to parental strains, Δ cas9 mutants were attenuated in murine models of hematogenous meningitis and vaginal colonization and exhibited significantly decreased invasion of human brain endothelium and adherence to vaginal epithelium. To determine if Cas9 alters transcription in GBS, we performed RNA-Seq analysis and found that 353 genes (>17% of the GBS genome) were differentially expressed between the parental WT and Δ cas9 mutant strain. Significantly dysregulated genes included those encoding predicted virulence factors, metabolic factors, two-component systems (TCS), and factors important for cell wall formation. These findings were confirmed by qRT-PCR and suggest that Cas9 may regulate a significant portion of the GBS genome. We studied one of the TCS regulators, CiaR, that was significantly downregulated in the Δ cas9 mutant strain. RNA-Seq analysis of the WT and Δ ciaR strains demonstrated that almost all CiaR-regulated genes were also significantly regulated by Cas9, suggesting that Cas9 may modulate GBS gene expression through other regulators. Further we show that CiaR contributes to GBS vaginal colonization and persistence. Altogether, these data highlight the potential complexity and importance of the non-canonical function of Cas9 in GBS colonization and disease.

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Section: Discussionsupporting

confidence: 84%

Cas9 Contributes to Group B Streptococcal Colonization and Disease

et al. 2019

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“…Another explanation might be a decrease in expression of genes encoding components of the CRISPR/Cas system in pgfur mutant strains compared with the wild-type counterparts. Recently, Heidrich et al [86] suggested a novel function of the CRISPR/Cas system of Neisseria meningitidis by demonstration of lower adhesion ability of a strain lacking the cas9 gene. In accordance with those findings, differences observed for mutant strains could be explained by changes in the composition of CRISPR/Cas-associated proteins (e.g., disruption of gene encoding Cas1 protein in the ATCC 33277 strain) and their expression, which results in significant differences observed only in the A7436 strain.…”

Section: Discussionmentioning

confidence: 99%

PgFur participates differentially in expression of virulence factors in more virulent A7436 and less virulent ATCC 33277 Porphyromonas gingivalis strains

et al. 2019

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Background Porphyromonas gingivalis is considered a keystone pathogen responsible for chronic periodontitis. Although several virulence factors produced by this bacterium are quite well characterized, very little is known about regulatory mechanisms that allow different strains of P. gingivalis to efficiently survive in the hostile environment of the oral cavity, a typical habitat characterized by low iron and heme concentrations. The aim of this study was to characterize P. gingivalis Fur homolog (PgFur) in terms of its role in production of virulence factors in more (A7436) and less (ATCC 33277) virulent strains. Results Expression of a pgfur depends on the growth phase and iron/heme concentration. To better understand the role played by the PgFur protein in P. gingivalis virulence under low- and high-iron/heme conditions, a pgfur -deficient ATCC 33277 strain (TO16) was constructed and its phenotype compared with that of a pgfur A7436-derived mutant strain (TO6). In contrast to the TO6 strain, the TO16 strain did not differ in the growth rate and hemolytic activity compared with the ATCC 33277 strain. However, both mutant strains were more sensitive to oxidative stress and they demonstrated changes in the production of lysine- (Kgp) and arginine-specific (Rgp) gingipains. In contrast to the wild-type strains, TO6 and TO16 mutant strains produced larger amounts of HmuY protein under high iron/heme conditions. We also demonstrated differences in production of glycoconjugates between the A7436 and ATCC 33277 strains and we found evidence that PgFur protein might regulate glycosylation process. Moreover, we revealed that PgFur protein plays a role in interactions with other periodontopathogens and is important for P. gingivalis infection of THP-1-derived macrophages and survival inside the cells. Deletion of the pgfur gene influences expression of many transcription factors, including two not yet characterized transcription factors from the Crp/Fnr family. We also observed lower expression of the CRISPR/Cas genes. Conclusions We show here for the first time that inactivation of the pgfur gene exerts a different influence on the phenotype of the A7436 and ATCC 33277 strains. Our findings further support the hypothesis that PgFur regulates expression of genes encoding surface virulence factors and/or genes involved in their maturation. Electronic supplementary material The online version of this article (10.1186/s12866-019-1511-x) contains supplementary material, which is available to authorized users.

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“…Beyond its immune function, a number of recent observations revealed unexpected roles for CRISPR-Cas systems in gene expression, autoimmunity, chromosomal segregation or rearrangement, and DNA repairing, although most of the mechanisms involved in these functions still remain unclear [10]. Of particular interest was the discovery of the involvement of CRISPR-Cas systems on the regulation of bacterial virulence [11][12][13].…”

Section: Introductionmentioning

confidence: 99%

The CRISPR-Cas systems were selectively inactivated during evolution of Bacillus cereus group for adaptation to diverse environments

et al. 2020

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CRISPR-Cas systems are considered as barriers to horizontal gene transfer (HGT). However, the influence of such systems on HGT within species is unclear. Also, little is known about the impact of CRISPR-Cas systems on bacterial evolution at the population level. Here, using Bacillus cereus sensu lato as model, we investigate the interplay between CRISPR-Cas systems and HGT at the population scale. We found that only a small fraction of the strains have CRISPR-Cas systems (13.9% of 1871), and most of such systems are defective based on their gene content analysis. Comparative genomic analysis revealed that the CRISPR-Cas systems are barriers to HGT within this group, since strains harboring active systems contain less mobile genetic elements (MGEs), have lower fraction of unique genes and also display limited environmental distributions than strains without active CRISPR-Cas systems. The introduction of a functional CRISPR-Cas system into a strain lacking the system resulted in reduced adaptability to various stresses and decreased pathogenicity of the transformant strain, indicating that B. cereus group strains could benefit from inactivating such systems. Our work provides a large-scale case to support that the CRISPR-Cas systems are barriers to HGT within species, and that in the B. cereus group the inactivation of CRISPR-Cas systems correlated with acquisition of MGEs that could result in better adaptation to diverse environments.

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The CRISPR/Cas system in Neisseria meningitidis affects bacterial adhesion to human nasopharyngeal epithelial cells

Cited by 17 publications

References 29 publications

Cas9 Contributes to Group B Streptococcal Colonization and Disease

Cas9 Contributes to Group B Streptococcal Colonization and Disease

PgFur participates differentially in expression of virulence factors in more virulent A7436 and less virulent ATCC 33277 Porphyromonas gingivalis strains

The CRISPR-Cas systems were selectively inactivated during evolution of Bacillus cereus group for adaptation to diverse environments

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