The Core Promoter of the Capsule Operon of Streptococcus pneumoniae Is Necessary for Colonization and Invasive Disease

Shainheit, Mara G.; Mulè, Matthew P.; Camilli, Andrew

doi:10.1128/iai.01289-13

Cited by 68 publications

(88 citation statements)

References 54 publications

(82 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The presence of such regulation is reflected by the observation of phase variation of pneumococci (8,54), and studies suggest that little capsule is produced when pneumococci are in contact with the epithelial cell layer (52). However, the mode of regulation remains to be further unraveled, and a number of genes and environmental factors seem to be important (45,(54)(55)(56)(57). The imaging tools used in this work will pave the way for new types of experiments which will help further our knowledge on the pathogenesis of the pneumococcus.…”

Section: Discussionmentioning

confidence: 99%

Bright Fluorescent Streptococcus pneumoniae for Live-Cell Imaging of Host-Pathogen Interactions

et al. 2015

View full text Add to dashboard Cite

c Streptococcus pneumoniae is a common nasopharyngeal resident in healthy people but, at the same time, one of the major causes of infectious diseases such as pneumonia, meningitis, and sepsis. The shift from commensal to pathogen and its interaction with host cells are poorly understood. One of the major limitations for research on pneumococcal-host interactions is the lack of suitable tools for live-cell imaging. To address this issue, we developed a generally applicable strategy to create genetically stable, highly fluorescent bacteria. Our strategy relies on fusing superfolder green fluorescent protein (GFP) or a far-red fluorescent protein (RFP) to the abundant histone-like protein HlpA. Due to efficient translation and limited cellular diffusion of these fusions, the cells are 25-fold brighter than those of the currently best available imaging S. pneumoniae strain. These novel bright pneumococcal strains are fully virulent, and the GFP reporter can be used for in situ imaging in mouse tissue. We used our reporter strains to study the effect of the polysaccharide capsule, a major pneumococcal virulence factor, on different stages of infection. By dual-color live-cell imaging experiments, we show that unencapsulated pneumococci adhere significantly better to human lung epithelial cells than encapsulated strains, in line with previous data obtained by classical approaches. We also confirm with live-cell imaging that the capsule protects pneumococci from neutrophil phagocytosis, demonstrating the versatility and usability of our reporters. The described imaging tools will pave the way for live-cell imaging of pneumococcal infection and help further understanding of the mechanisms of pneumococcal pathogenesis. Streptococcus pneumoniae is a major cause of morbidity and mortality worldwide, and pneumococcal infections (e.g., pneumonia, septicemia, and meningitis) kill more than 1 million people every year (1). Pneumococci are also quiescent colonizers of the upper respiratory tract, particularly in children, but little is known about the mechanisms underlying the transition from commensal to pathogen. It is therefore of crucial importance to understand the entire pneumococcal pathogenesis cycle in detail.The polysaccharide capsule covering the cell surface is the most central virulence factor of S. pneumoniae. The involvement of the capsule in pneumococcal pathogenesis has been appreciated since Griffith in 1928 (2) published his famous transformation experiment with rough and smooth strains of S. pneumoniae. Today, it is known that the bulky capsule, which is either negatively charged or neutral, contributes to pathogenesis by protecting pneumococci against the human immune system. For example, the capsule hinders phagocytosis and inhibits complement activity (3-6). Over 90 different pneumococcal serotypes have been identified to date (7), and the different serotypes vary in how well they protect the bacteria against phagocytosis (6). Furthermore, the amount of capsule differs between bacteria, and it has been s...

show abstract

Section: Discussionmentioning

confidence: 99%

Bright Fluorescent Streptococcus pneumoniae for Live-Cell Imaging of Host-Pathogen Interactions

et al. 2015

View full text Add to dashboard Cite

show abstract

“…As a positive control for cotranscription, the intergenic region of the previously characterized SPD2018-cbpA operon (52) was also amplified with primers Pr8105 and Pr8106. The mRNA level of the cps locus was quantified by quantitative RT-PCR (qRT-PCR) as described previously (40). Primer pairs Pr7705/Pr7706 and Pr7707/Pr7708 were used to amplify cps2A and cps2E, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…Shainheit et al showed that the sequence between the Ϫ35 promoter motif and the transcription start site of the cps locus in the type 4 strain TIGR4 is essential for the transcription of the cps gene cluster (40). There is extensive sequence diversity upstream of the transcription start sites.…”

mentioning

confidence: 99%

“…The majority of the SOs consists of one or more insertion elements (IE), a repeat unit of pneumococcus (RUP), and a conserved sequence immediately upstream of cpsA that contains the predicted Ϫ10 and Ϫ35 promoter motifs. Except for the core promoter recently defined in TIGR4 (40), the precise constituents of the cps promoter in S. pneumoniae remain undefined.…”

mentioning

confidence: 99%

“…The transcription start sites of the S. pneumoniae cps locus in the type 1 strain 13868 (39) and the type 4 strain TIGR4 (40) have been mapped to the 23rd and 24th nucleotides upstream of the cpsA coding sequence, respectively. Shainheit et al showed that the sequence between the Ϫ35 promoter motif and the transcription start site of the cps locus in the type 4 strain TIGR4 is essential for the transcription of the cps gene cluster (40).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Sequence Elements Upstream of the Core Promoter Are Necessary for Full Transcription of the Capsule Gene Operon in Streptococcus pneumoniae Strain D39

et al. 2015

View full text Add to dashboard Cite

e Streptococcus pneumoniae is a major bacterial pathogen in humans. Its polysaccharide capsule is a key virulence factor that promotes bacterial evasion of human phagocytic killing. While S. pneumoniae produces at least 94 antigenically different types of capsule, the genes for biosynthesis of almost all capsular types are arranged in the same locus. The transcription of the capsular polysaccharide (cps) locus is not well understood. This study determined the transcriptional features of the cps locus in the type 2 virulent strain D39. The initial analysis revealed that the cps genes are cotranscribed from a major transcription start site at the ؊25 nucleotide (G) upstream of cps2A, the first gene in the locus. Using unmarked chromosomal truncations and a luciferasebased transcriptional reporter, we showed that the full transcription of the cps genes not only depends on the core promoter immediately upstream of cps2A, but also requires additional elements upstream of the core promoter, particularly a 59-bp sequence immediately upstream of the core promoter. Unmarked deletions of these promoter elements in the D39 genome also led to significant reduction in CPS production and virulence in mice. Lastly, common cps gene (cps2ABCD) mutants did not show significant abnormality in cps transcription, although they produced significantly less CPS, indicating that the CpsABCD proteins are involved in the encapsulation of S. pneumoniae in a posttranscriptional manner. This study has yielded important information on the transcriptional characteristics of the cps locus in S. pneumoniae. Streptococcus pneumoniae (pneumococcus) is a major cause of bacterial infections in humans, including otitis media, pneumonia, bacteremia, and meningitis (1). As the outermost structure, the capsule is the major virulence factor of S. pneumoniae and protects the bacterium by interfering with host phagocytic killing (2). Virtually all of the clinical isolates are encapsulated, and mutations in the cps locus result in the loss of virulence (3). The capsule of S. pneumoniae is composed of capsular polysaccharides (CPSs). The CPSs are immunogenic and thus serve as the target antigens for the current pneumococcal vaccines (4). Due to host immune selection that targets the capsule, the CPSs have undergone extensive chemical and antigenic variation via genetic diversity in the CPS biosynthesis genes. At least 94 antigenically distinct capsular serotypes have been identified in S. pneumoniae (5, 6). While the CPSs of types 3 and 37 are produced as relatively simple repeats of polysaccharides by the synthase pathway (7, 8), all other capsule types are much more complex and are synthesized by WZY-dependent polymerization, a mechanism of capsule production that is widely found in other bacteria (9-11).Except for type 37, all of the CPS types in S. pneumoniae are determined by a set of capsule biosynthesis genes, which are historically designated cps or cap (12). Bentley et al. recently renamed the pneumococcal capsule genes on the basis of their overall...

show abstract

Pneumococcal wall teichoic acid is required for the pathogenesis of Streptococcus pneumoniae in murine models

Wang

Huang

et al. 2015

J Microbiol.

View full text Add to dashboard Cite

Pneumococcal asymptomatic colonization of the respiratory tracts is a major risk for invasive pneumococcal disease. We have previously shown that pneumococcal wall teichoic acid (WTA) was involved in pneumococcal infection of sepsis and adherence to epithelial and endothelial cells. In this study, we investigated the contribution of pneumococcal WTA to bacterial colonization and dissemination in murine models. The result showed that nasopharynx colonizing D39 bacterial cells have a distinct phenotype showing an increased exposure of teichoic acids relative to medium-grown bacteria. The WTA-deficient mutants were impaired in their colonization to the nasopharynx and lungs, and led to a mild inflammation in the lungs at 36 h post-inoculation. Pretreatment of the murine nares with WTA reduced the ability of wild type D39 bacteria to colonize the nasopharynx. In addition, the WTA-deficient strain was impaired in its ability to invade the blood and brain following intranasal administration. WTA-deficient D39 strain was reduced in C3 deposition but was more susceptible to the killing by the neutrophils as compared with its parent strain. Our results also demonstrated that the WTA enhanced pneumococcal colonization and dissemination independently of the host strains. These results indicate that WTA plays an important role in pneumococcal pathogenesis, both in colonization and dissemination processes.

show abstract

The Core Promoter of the Capsule Operon of Streptococcus pneumoniae Is Necessary for Colonization and Invasive Disease

Cited by 68 publications

References 54 publications

Bright Fluorescent Streptococcus pneumoniae for Live-Cell Imaging of Host-Pathogen Interactions

Bright Fluorescent Streptococcus pneumoniae for Live-Cell Imaging of Host-Pathogen Interactions

Sequence Elements Upstream of the Core Promoter Are Necessary for Full Transcription of the Capsule Gene Operon in Streptococcus pneumoniae Strain D39

Pneumococcal wall teichoic acid is required for the pathogenesis of Streptococcus pneumoniae in murine models

Contact Info

Product

Resources

About