Transcriptional Regulation in the Streptococcus pneumoniae rlrA Pathogenicity Islet by RlrA

ABSTRACT The proper temporal expression of virulence genes during infection is crucial to the infectious life cycle of microbial pathogens, particularly in pathogens that encounter a multitude of environments in eukaryotic hosts. Streptococcus pneumoniae normally colonizes the nasopharynges of healthy adults but can cause a range of diseases at a variety of host sites. Transcriptional regulators that are essential for full virulence of S. pneumoniae in different animal models have been identified. One such regulator, rlrA, is required for colonization of the nasopharynx and lung infection but is dispensable for systemic infection. Previous work has shown that rlrA lies in a 12-kb pathogenicity islet, divergently opposed to three putative sortase-anchored surface proteins and three sortase enzymes. In addition to rlrA, one of the putative surface proteins and one of the sortases have also been shown to be essential for lung infection. In this work, we demonstrate that RlrA is a positive regulator of all seven genes in the rlrA pathogenicity islet, with transcriptional activation occurring at four different promoters in the islet with AT-rich sequences. These promoters direct the expression of rlrA itself, the three sortases, rrgA, and rrgBC. These data are consistent with the model whereby the rlrA pathogenicity islet acts in an autonomous manner to alter the bacterial surface components that interact with the pulmonary and nasopharyngeal environments.

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Transformation of nonencapsulated Streptococcus pneumoniae during systemic infection

Scientific Reports ◽

10.1038/s41598-020-75988-5 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Jessica L. Bradshaw ◽

Iftekhar M. Rafiqullah ◽

D. Ashley Robinson ◽

Larry S. McDaniel

Keyword(s):

Streptococcus Pneumoniae ◽

Systemic Infection ◽

Dna Uptake ◽

Pathogenic Potential ◽

Bacterial Surface ◽

Capsule Production ◽

Virulent Strains ◽

Capsule Locus ◽

Ear Infections ◽

Complement Deposition

Abstract Streptococcus pneumoniae (pneumococcus) is a principal cause of bacterial middle ear infections, pneumonia, and meningitis. Capsule-targeted pneumococcal vaccines have likely contributed to increased carriage of nonencapsulated S. pneumoniae (NESp). Some NESp lineages are associated with highly efficient DNA uptake and transformation frequencies. However, NESp strains lack capsule that may increase disease severity. We tested the hypothesis that NESp could acquire capsule during systemic infection and transform into more virulent pneumococci. We reveal that NESp strains MNZ67 and MNZ41 are highly transformable and resistant to multiple antibiotics. Natural transformation of NESp when co-administered with heat-killed encapsulated strain WU2 in a murine model of systemic infection resulted in encapsulation of NESp and increased virulence during bacteremia. Functional capsule production increased the pathogenic potential of MNZ67 by significantly decreasing complement deposition on the bacterial surface. However, capsule acquisition did not further decrease complement deposition on the relatively highly pathogenic strain MNZ41. Whole genome sequencing of select transformants demonstrated that recombination of up to 56.7 kbp length occurred at the capsule locus, along with additional recombination occurring at distal sites harboring virulence-associated genes. These findings indicate NESp can compensate for lack of capsule production and rapidly evolve into more virulent strains.

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Attachment of Streptococcus Pneumoniae to Human Pharyngeal Epithelial Cells in Vitro—Mechanism of Binding

Otolaryngology ◽

10.1177/019459988409200304 ◽

1984 ◽

Vol 92 (3) ◽

pp. 266-269 ◽

Cited By ~ 6

Author(s):

B Andersson ◽

A Fogh ◽

F. JØRgensen ◽

S Larsson ◽

H Leffler ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Epithelial Cell ◽

Epithelial Cells ◽

Otitis Media ◽

Binding Capacity ◽

Cell Receptor ◽

Surface Proteins ◽

Bacterial Surface

To colonize mucosal surfaces and to invade underlying tissues, bacteria need to bind to components of the mucosa. Unattached bacteria are transported away from the surface with the fluid flow. By binding to the nasopharyngeal mucosa, Streptococcus pneumoniae causing otitis media may persist at the site of infection. High binding capacity of the bacterium and increased receptivity of the epithelial cells for attaching bacteria may both contribute to the susceptibility of patients prone to otitis. Thus, epithelial cells from children with frequent episodes of otitis bind attaching bacteria more readily than do cells from age-matched controls. The binding mechanism probably involves bacterial surface proteins and epithelial cell surface glycoconjugate receptors. Evidence is presented that phosphorylcholine, a component of the bacterial surface, as well as epithelial cell receptor analogues, that is, natural or synthetic saccharides analogous to the lactoneoseries of glycolipids, inhibits pneumococcal attachment. Inhibition of bacterial binding in vivo may be a new approach to prophylaxis against otitis media.

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Unveiling molecular mechanisms of bacterial surface proteins: Streptococcus pneumoniae as a model organism for structural studies

Cellular and Molecular Life Sciences ◽

10.1007/s00018-007-7125-8 ◽

2007 ◽

Vol 64 (21) ◽

pp. 2799-2822 ◽

Cited By ~ 38

Author(s):

M. J. Jedrzejas

Keyword(s):

Streptococcus Pneumoniae ◽

Molecular Mechanisms ◽

Model Organism ◽

Surface Proteins ◽

Structural Studies ◽

Bacterial Surface

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Pneumococcal capsule blocks protection by immunization with conserved surface proteins

npj Vaccines ◽

10.1038/s41541-021-00413-5 ◽

2021 ◽

Vol 6 (1) ◽

Author(s):

Tonia Zangari ◽

M. Ammar Zafar ◽

John A. Lees ◽

Annie R. Abruzzo ◽

Gavyn Chern Wei Bee ◽

...

Keyword(s):

Streptococcus Pneumoniae ◽

Capsular Polysaccharide ◽

Surface Proteins ◽

Mucosal Protection ◽

Protein Antigens ◽

Protein Targets ◽

Bacterial Surface ◽

Adult Mice ◽

Genome Wide ◽

Vaccine Antigens

AbstractVaccines targeting Streptococcus pneumoniae (Spn) are limited by dependence on capsular polysaccharide and its serotype diversity. More broadly-based approaches using common protein antigens have not resulted in a licensed vaccine. Herein, we used an unbiased, genome-wide approach to find novel vaccine antigens to disrupt carriage modeled in mice. A Tn-Seq screen identified 198 genes required for colonization of which 16 are known to express conserved, immunogenic surface proteins. After testing defined mutants for impaired colonization of infant and adult mice, 5 validated candidates (StkP, PenA/Pbp2a, PgdA, HtrA, and LytD/Pce/CbpE) were used as immunogens. Despite induction of antibody recognizing the Spn cell surface, there was no protection against Spn colonization. There was, however, protection against an unencapsulated Spn mutant. This result correlated with increased antibody binding to the bacterial surface in the absence of capsule. Our findings demonstrate how the pneumococcal capsule interferes with mucosal protection by antibody to common protein targets.

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Detection of Individual Microbial Pathogens by Proximity Ligation

Clinical Chemistry ◽

10.1373/clinchem.2005.065847 ◽

2006 ◽

Vol 52 (6) ◽

pp. 1152-1160 ◽

Cited By ~ 63

Author(s):

Sigrun M Gustafsdottir ◽

Ann Nordengrahn ◽

Simon Fredriksson ◽

Per Wallgren ◽

Esteban Rivera ◽

...

Keyword(s):

Nucleic Acid ◽

Surface Proteins ◽

Nucleic Acid Amplification ◽

Microbial Pathogens ◽

Detection Sensitivity ◽

Infectious Agents ◽

Bacterial Surface ◽

Virus Particles ◽

Proximity Ligation ◽

Dna Strands

Abstract Background: Nucleic acid amplification allows the detection of single infectious agents. Protein-based assays, although they provide information on ongoing infections, have substantially less detection sensitivity. Methods: We used proximity ligation reactions to detect proteins on bacteria and virus particles via nucleic acid amplification. Antibodies recognizing viral or bacterial surface proteins were equipped with DNA strands that could be joined by ligation when several antibodies were bound in proximity to surface proteins of individual infectious agents. Results: Detection sensitivities similar to those of nucleic acid-based detection reactions were achieved directly in infected samples for a parvovirus and an intracellular bacterium. Conclusions: This method enables detection of ligated DNA strands with good sensitivity by real-time PCR and could be of value for early diagnosis of infectious disease and in biodefense.

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Faculty Opinions recommendation of Signal sequence directs localized secretion of bacterial surface proteins.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1040260.488992 ◽

2006 ◽

Author(s):

Victor DiRita

Keyword(s):

Signal Sequence ◽

Surface Proteins ◽

Bacterial Surface

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Faculty Opinions recommendation of Surface Proteins and Pneumolysin of Encapsulated and Nonencapsulated Streptococcus pneumoniae Mediate Virulence in a Chinchilla Model of Otitis Media.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726394313.793522904 ◽

2016 ◽

Author(s):

Charles Feldman

Keyword(s):

Streptococcus Pneumoniae ◽

Otitis Media ◽

Surface Proteins

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Identification and Characterization of TUP1-Regulated Genes in Candida albicans

Genetics ◽

10.1093/genetics/156.1.31 ◽

2000 ◽

Vol 156 (1) ◽

pp. 31-44 ◽

Cited By ~ 7

Author(s):

Burkhard R Braun ◽

W Steven Head ◽

Ming X Wang ◽

Alexander D Johnson

Keyword(s):

Candida Albicans ◽

Systemic Infection ◽

Subtractive Hybridization ◽

Filamentous Growth ◽

Surface Proteins ◽

Infection Model ◽

Ferric Reductase ◽

Pathogenesis Related Protein ◽

Plant Pathogenesis ◽

Rnase T2

Abstract TUP1 encodes a transcriptional repressor that negatively controls filamentous growth in Candida albicans. Using subtractive hybridization, we identified six genes, termed repressed by TUP1 (RBT), whose expression is regulated by TUP1. One of the genes (HWP1) has previously been characterized, and a seventh TUP1-repressed gene (WAP1) was recovered due to its high similarity to RBT5. These genes all encode secreted or cell surface proteins, and four out of the seven (HWP1, RBT1, RBT5, and WAP1) encode putatively GPI-modified cell wall proteins. The remaining three, RBT2, RBT4, and RBT7, encode, respectively, an apparent ferric reductase, a plant pathogenesis-related protein (PR-1), and a putative secreted RNase T2. The expression of RBT1, RBT4, RBT5, HWP1, and WAP1 was induced in wild-type cells during the switch from the yeast form to filamentous growth, indicating the importance of TUP1 in regulating this process and implicating the RBTs in hyphal-specific functions. We produced knockout strains in C. albicans for RBT1, RBT2, RBT4, RBT5, and WAP1 and detected no phenotypes on several laboratory media. However, two animal models for C. albicans infection, a rabbit cornea model and a mouse systemic infection model, revealed that rbt1Δ and rbt4Δ strains had significantly reduced virulence. TUP1 appears, therefore, to regulate many genes in C. albicans, a significant fraction of which are induced during filamentous growth, and some of which participate in pathogenesis.

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