Streptococcus pyogenes: Insight into the function of the streptococcal superantigens

2007 ◽  
Vol 39 (1) ◽  
pp. 12-19 ◽  
Author(s):  
Shiranee Sriskandan ◽  
Lee Faulkner ◽  
Philip Hopkins
Keyword(s):  
Streptococcus Pyogenes ◽  
Insight Into

An insight into the protospacer adjacent motif of Streptococcus pyogenes Cas9 with artificially stimulated RNA-guided-Cas9 DNA cleavage flexibility

RSC Advances ◽  
2016 ◽  
Vol 6 (40) ◽  
pp. 33514-33522 ◽  
Author(s):  
Yujie Geng ◽  
Zixin Deng ◽  
Yuhui Sun
Keyword(s):  
Streptococcus Pyogenes ◽  
Dna Cleavage ◽  
Protospacer Adjacent Motif ◽  
Insight Into

The interspace between the protospacer and NGG affects SpyCas9 cleavage, and in vitro annealing with PAMmer facilitates cleavage of non-PAM sites.

scholarly journals Survival Strategies of Streptococcus pyogenes in Response to Phage Infection

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 612
Author(s):  
Dior Beerens ◽  
Sandra Franch-Arroyo ◽  
Timothy J. Sullivan ◽  
Christian Goosmann ◽  
Volker Brinkmann ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Membrane Vesicles ◽  
Phage Infection ◽  
Survival Strategies ◽  
Modular Organization ◽  
Lytic Phage ◽  
Bacterial Host ◽  
Host Chromosome ◽  
Double Stranded Dna ◽  
Insight Into

Bacteriophages exert strong evolutionary pressure on their microbial hosts. In their lytic lifecycle, complete bacterial subpopulations are utilized as hosts for bacteriophage replication. However, during their lysogenic lifecycle, bacteriophages can integrate into the host chromosome and alter the host’s genomic make-up, possibly resulting in evolutionary important adjustments. Not surprisingly, bacteria have evolved sophisticated immune systems to protect against phage infection. Streptococcus pyogenes isolates are frequently lysogenic and their prophages have been shown to be major contributors to the virulence of this pathogen. Most S. pyogenes phage research has focused on genomic prophages in relation to virulence, but little is known about the defensive arsenal of S. pyogenes against lytic phage infection. Here, we characterized Phage A1, an S. pyogenes bacteriophage, and investigated several mechanisms that S. pyogenes utilizes to protect itself against phage predation. We show that Phage A1 belongs to the Siphoviridae family and contains a circular double-stranded DNA genome that follows a modular organization described for other streptococcal phages. After infection, the Phage A1 genome can be detected in isolated S. pyogenes survivor strains, which enables the survival of the bacterial host and Phage A1 resistance. Furthermore, we demonstrate that the type II-A CRISPR-Cas system of S. pyogenes acquires new spacers upon phage infection, which are increasingly detectable in the absence of a capsule. Lastly, we show that S. pyogenes produces membrane vesicles that bind to phages, thereby limiting the pool of phages available for infection. Altogether, this work provides novel insight into survival strategies employed by S. pyogenes to combat phage predation.

scholarly journals Genetic Inactivation of an Extracellular Cysteine Protease (SpeB) Expressed by Streptococcus pyogenes Decreases Resistance to Phagocytosis and Dissemination to Organs

1998 ◽  
Vol 66 (2) ◽  
pp. 771-776 ◽  
Author(s):  
Slawomir Lukomski ◽  
Eugene H. Burns ◽  
Philip R. Wyde ◽  
Andreas Podbielski ◽  
Jacqueline Rurangirwa ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
Cysteine Protease ◽  
Inflammatory Responses ◽  
Wild Type ◽  
Genetic Inactivation ◽  
Streptococcal Pyrogenic Exotoxin B ◽  
Mutant Derivative ◽  
Important Virulence Factor ◽  
Type Strains ◽  
Insight Into

ABSTRACT Streptococcal pyrogenic exotoxin B (SpeB), a conserved cysteine protease expressed by virtually all Streptococcus pyogenes strains, has recently been shown to be an important virulence factor (S. Lukomski, S. Sreevatsan, C. Amberg, W. Reichardt, M. Woischnik, A. Podbielski, and J. M. Musser, J. Clin. Invest. 99:2574–2580, 1997). Genetic inactivation of SpeB significantly decreased the lethality of a serotype M49 strain for mice and abolished the lethality of a serotype M3 strain after intraperitoneal (i.p.) injection. In the present study, a wild-type M3 isolate and an M3 speB mutant derivative were used to investigate the mechanism responsible for altered virulence. Following i.p. injection, the mutant and wild-type strains induced virtually identical cellular inflammatory responses, characterized largely by an influx of polymorphonuclear leukocytes (PMNs). In addition, the mutant and wild-type strains rapidly entered the blood and were recovered from all organs examined. However, significantly fewer (P < 0.05) CFUs of the isogenic mutant derivative than of the wild-type parent strain were recovered from blood and organs. PMNs effectively cleared the M3 speB mutant from the peritoneum by 22 h, thereby sparing the host. In contrast, the wild-type M3 strain continued to replicate intraperitoneally and had the ability to kill phagocytes. This process allowed the wild-type strain to continuously disseminate, resulting in host death. Our results indicate that genetic inactivation of the cysteine protease decreased the resistance of the mutant to phagocytosis and impaired its subsequent dissemination to organs. These results provide insight into the detrimental effect of SpeB inactivation on virulence.

The deficient cleavage of M protein-bound IgG by IdeS: Insight into the escape of Streptococcus pyogenes from antibody-mediated immunity

2011 ◽  
Vol 49 (1-2) ◽  
pp. 134-142 ◽  
Author(s):  
Yu-Fang Su ◽  
Woei-Jer Chuang ◽  
Shih-Min Wang ◽  
Wen-Yi Chen ◽  
Chuan Chiang-Ni ◽  
...  
Keyword(s):  
Streptococcus Pyogenes ◽  
M Protein ◽  
Insight Into

scholarly journals Factors That Cause Trimethoprim Resistance in Streptococcus pyogenes

2014 ◽  
Vol 58 (4) ◽  
pp. 2281-2288 ◽  
Author(s):  
René Bergmann ◽  
Mark van der Linden ◽  
Gursharan S. Chhatwal ◽  
D. Patric Nitsche-Schmitz
Keyword(s):  
Streptococcus Pneumoniae ◽  
Amino Acid ◽  
Nucleotide Sequence ◽  
Streptococcus Pyogenes ◽  
Dihydrofolate Reductase ◽  
Molecular Basis ◽  
Rapid Development ◽  
Antibiotic Agent ◽  
Content Type ◽  
Insight Into

ABSTRACTThe use of trimethoprim in treatment ofStreptococcus pyogenesinfections has long been discouraged because it has been widely believed that this pathogen is resistant to this antibiotic. To gain more insight into the extent and molecular basis of trimethoprim resistance inS. pyogenes, we tested isolates from India and Germany and sought the factors that conferred the resistance. Resistant isolates were identified in tests for trimethoprim or trimethoprim-sulfamethoxazole (SXT) susceptibility. Resistant isolates were screened for the known horizontally transferable trimethoprim-insensitive dihydrofolate reductase (dfr) genesdfrG,dfrF,dfrA,dfrD, anddfrK. The nucleotide sequence of the intrinsicdfrgene was determined for resistant isolates lacking the horizontally transferable genes. Based on tentative criteria, 69 out of 268 isolates (25.7%) from India were resistant to trimethoprim. Occurring in 42 of the 69 resistant isolates (60.9%),dfrFappeared more frequently thandfrG(23 isolates; 33.3%) in India. ThedfrFgene was also present in a collection of SXT-resistant isolates from Germany, in which it was the only detected trimethoprim resistance factor. ThedfrFgene caused resistance in 4 out of 5 trimethoprim-resistant isolates from the German collection. An amino acid substitution in the intrinsic dihydrofolate reductase known from trimethoprim-resistantStreptococcus pneumoniaeconferred resistance toS. pyogenesisolates ofemmtype 102.2, which lacked other aforementioneddfrgenes. Trimethoprim may be more useful in treatment ofS. pyogenesinfections than previously thought. However, the factors described herein may lead to the rapid development and spread of resistance ofS. pyogenesto this antibiotic agent.

Calibration problems in hydrogen luminosities

1966 ◽  
Vol 24 ◽  
pp. 322-330
Author(s):  
A. Beer
Keyword(s):  
Galactic Structure ◽  
B Stars ◽  
Insight Into

The investigations which I should like to summarize in this paper concern recent photo-electric luminosity determinations of O and B stars. Their final aim has been the derivation of new stellar distances, and some insight into certain patterns of galactic structure.

Stochasting modeling of planetary ring systems

1984 ◽  
Vol 75 ◽  
pp. 461-469 ◽  
Author(s):  
Robert W. Hart
Keyword(s):  
Maximum Entropy ◽  
Ring System ◽  
The Sun ◽  
Ultimate State ◽  
Interparticle Interactions ◽  
Ring Systems ◽  
First Order ◽  
Planetary Ring ◽  
Insight Into

ABSTRACTThis paper models maximum entropy configurations of idealized gravitational ring systems. Such configurations are of interest because systems generally evolve toward an ultimate state of maximum randomness. For simplicity, attention is confined to ultimate states for which interparticle interactions are no longer of first order importance. The planets, in their orbits about the sun, are one example of such a ring system. The extent to which the present approximation yields insight into ring systems such as Saturn's is explored briefly.

Skeletal elements of crinoid echinoderms: High-resolution structural and microanalytical results

1983 ◽  
Vol 41 ◽  
pp. 194-195
Author(s):  
D. F. Blake ◽  
L. F. Allard ◽  
D. R. Peacor
Keyword(s):  
High Resolution ◽  
Marine Invertebrates ◽  
Sea Urchins ◽  
Structural Features ◽  
Sea Stars ◽  
High Resolution Tem ◽  
Relationship Of ◽  
The Relationship ◽  
Insight Into

Echinodermata is a phylum of marine invertebrates which has been extant since Cambrian time (c.a. 500 m.y. before the present). Modern examples of echinoderms include sea urchins, sea stars, and sea lilies (crinoids). The endoskeletons of echinoderms are composed of plates or ossicles (Fig. 1) which are with few exceptions, porous, single crystals of high-magnesian calcite. Despite their single crystal nature, fracture surfaces do not exhibit the near-perfect {10.4} cleavage characteristic of inorganic calcite. This paradoxical mix of biogenic and inorganic features has prompted much recent work on echinoderm skeletal crystallography. Furthermore, fossil echinoderm hard parts comprise a volumetrically significant portion of some marine limestones sequences. The ultrastructural and microchemical characterization of modern skeletal material should lend insight into: 1). The nature of the biogenic processes involved, for example, the relationship of Mg heterogeneity to morphological and structural features in modern echinoderm material, and 2). The nature of the diagenetic changes undergone by their ancient, fossilized counterparts. In this study, high resolution TEM (HRTEM), high voltage TEM (HVTEM), and STEM microanalysis are used to characterize tha ultrastructural and microchemical composition of skeletal elements of the modern crinoid Neocrinus blakei.

Structure and function of neural networks in the retina

1988 ◽  
Vol 46 ◽  
pp. 26-27
Author(s):  
Peter Sterling
Keyword(s):  
Ganglion Cells ◽  
Three Dimensional ◽  
Structure And Function ◽  
Synaptic Connections ◽  
Visual Axis ◽  
One Dimensional ◽  
Cat Retina ◽  
Ultrathin Sections ◽  
And Function ◽  
Insight Into

The synaptic connections in cat retina that link photoreceptors to ganglion cells have been analyzed quantitatively. Our approach has been to prepare serial, ultrathin sections and photograph en montage at low magnification (˜2000X) in the electron microscope. Six series, 100-300 sections long, have been prepared over the last decade. They derive from different cats but always from the same region of retina, about one degree from the center of the visual axis. The material has been analyzed by reconstructing adjacent neurons in each array and then identifying systematically the synaptic connections between arrays. Most reconstructions were done manually by tracing the outlines of processes in successive sections onto acetate sheets aligned on a cartoonist's jig. The tracings were then digitized, stacked by computer, and printed with the hidden lines removed. The results have provided rather than the usual one-dimensional account of pathways, a three-dimensional account of circuits. From this has emerged insight into the functional architecture.

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