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Background
One of the most important global pathogens infecting all age groups is Streptococcus pneumoniae (the ‘pneumococcus’). Pneumococci reside in the paediatric nasopharynx, where they compete for space and resources, and one competition strategy is to produce a bacteriocin (antimicrobial peptide or protein) to attack other bacteria and an immunity protein to protect against self-destruction. We analysed a collection of 336 diverse pneumococcal genomes dating from 1916 onwards, identified bacteriocin cassettes, detailed their genetic composition and sequence diversity, and evaluated the data in the context of the pneumococcal population structure.Results
We found that all genomes maintained a blp bacteriocin cassette and we identified several novel blp cassettes and genes. The composition of the ‘bacteriocin/immunity region’ of the blp cassette was highly variable: one cassette possessed six bacteriocin genes and eight putative immunity genes, whereas another cassette had only one of each. Both widely-distributed and highly clonal blp cassettes were identified. Most surprisingly, one-third of pneumococcal genomes also possessed a cassette encoding a novel circular bacteriocin that we called pneumocyclicin, which shared a similar genetic organisation to well-characterised circular bacteriocin cassettes in other bacterial species. Pneumocyclicin cassettes were mainly of one genetic cluster and largely found among seven major pneumococcal clonal complexes.Conclusions
These detailed genomic analyses revealed a novel pneumocyclicin cassette and a wide variety of blp bacteriocin cassettes, suggesting that competition in the nasopharynx is a complex biological phenomenon.Electronic supplementary material
The online version of this article (doi:10.1186/s12864-015-1729-4) contains supplementary material, which is available to authorized users. 相似文献32.
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Harry B. Hines Frank Lebeda Martha Hale Ernst E. Brueggemann 《Applied microbiology》2005,71(8):4478-4486
Botulinum toxin analysis has renewed importance. This study included the use of nanochromatography-nanoelectrospray-mass spectrometry/mass spectrometry to characterize the protein composition of botulinum progenitor toxins and to assign botulinum progenitor toxins to their proper serotype and strain by using currently available sequence information. Clostridium botulinum progenitor toxins from strains Hall, Okra, Stockholm, MDPH, Alaska, and Langeland and 89 representing serotypes A through G, respectively, were reduced, alkylated, digested with trypsin, and identified by matching the processed product ion spectra of the tryptic peptides to proteins in accessible databases. All proteins known to be present in progenitor toxins from each serotype were identified. Additional proteins, including flagellins, ORF-X1, and neurotoxin binding protein, not previously reported to be associated with progenitor toxins, were present also in samples from several serotypes. Protein identification was used to assign toxins to a serotype and strain. Serotype assignments were accurate, and strain assignments were best when either sufficient nucleotide or amino acid sequence data were available. Minor difficulties were encountered using neurotoxin-associated protein identification for assigning serotype and strain. This study found that combined nanoscale chromatographic and mass spectrometric techniques can characterize C. botulinum progenitor toxin protein composition and that serotype/strain assignments based upon these proteins can provide accurate serotype and, in most instances, strain assignments using currently available information. Assignment accuracy will continue to improve as more nucleotide/amino acid sequence information becomes available for different botulinum strains. 相似文献
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EG Smirnova GS Muromtsev AV Osipenko EE Khavkin LS Yaguzhinsky 《Biochemistry. Biokhimii?a》1998,63(9):1021-1028
Activation of highly specific biochemical processes by simple chemical agents is demonstrated for morphogenesis (anlage and development of female gametophyte in cereal) and mitosis (in cell cultures and animal and plant tissues). The effects of these agents are tissue-specific. Structure--activity relationship is analyzed in this group of compounds. Thus, the phenomenon reveals the exact pathways of the influence of allelopathic and anthropogenic chemical agents on evolution of plant biocenoses. 相似文献
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Hanekamp CE Peels KH Koolen JJ Bonnier HJ 《International journal of cardiovascular interventions》1998,1(2):105-107
In this case report the occurrence of a catheter-induced coronary artery dissection is described. In our patient, angiography showed a mushroom-shaped exudate above the left main coronary artery. Intravascular ultrasound revealed a circular dissection with a huge false lumen connected to the true lumen by a small intimal tear. A brief review of the literature on catheter-induced coronary dissection is included. We believe that this case report provides a good illustration of the need for careful reviewing of indications for angiography. Although procedural risks are low, angiography remains an invasive diagnostic test with the potential to cause severe complications. 相似文献
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Claudia Mastroeni Til Ole Bergmann Vincenzo Rizzo Christoph Ritter Christine Klein Ines Pohlmann Norbert Brueggemann Angelo Quartarone Hartwig Roman Siebner 《PloS one》2013,8(2)
Repetitive transcranial magnetic stimulation (rTMS) of the human motor hand area (M1HAND) can induce lasting changes in corticospinal excitability as indexed by a change in amplitude of the motor-evoked potential. The plasticity-inducing effects of rTMS in M1HAND show substantial inter-individual variability which has been partially attributed to the val66met polymorphism in the brain-derived neurotrophic factor (BDNF) gene. Here we used theta burst stimulation (TBS) to examine whether the BDNF val66met genotype can be used to predict the expression of TBS-induced homeostatic metaplasticity in human M1HAND. TBS is a patterned rTMS protocol with intermittent TBS (iTBS) usually inducing a lasting increase and continuous TBS (cTBS) a lasting decrease in corticospinal excitability. In three separate sessions, healthy val66met (n = 12) and val66val (n = 17) carriers received neuronavigated cTBS followed by cTBS (n = 27), cTBS followed by iTBS (n = 29), and iTBS followed by iTBS (n = 28). Participants and examiner were blinded to the genotype at the time of examination. As expected, the first TBS intervention induced a decrease (cTBS) and increase (iTBS) in corticospinal excitability, respectively, at the same time priming the after effects caused by the second TBS intervention in a homeostatic fashion. Critically, val66met carriers and val66val carriers showed very similar response patterns to cTBS and iTBS regardless of the order of TBS interventions. Since none of the observed TBS effects was modulated by the BDNF val66met polymorphism, our results do not support the notion that the BDNF val66met genotype is a major player with regard to TBS-induced plasticity and metaplasticity in the human M1HAND. 相似文献
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High-performance liquid chromatography-mass selective detection assay for adenine released from a synthetic RNA substrate by ricin A chain 总被引:2,自引:0,他引:2
High-performance liquid chromatography (HPLC) and selected ion monitoring mass spectrometry (MS) were used to develop a quantitative assay for adenine released from a synthetic RNA substrate by ricin A chain, which contains the toxin's N-glycosidase activity. Because ricin and ricin A chain have potential applications as biotherapeutics and bioweapons, assays are needed to evaluate potency and potential inhibitors of activity. The detection limit for adenine was 0.02 microM (2.4 ng/ml), and the standard curve was linear up to 27.3 microM. The lower limit of quantitation was 0.27 microM and was reproducible throughout this range. Reaction characterization showed that most adenine was released by 5h and that the reaction could not be fully stopped with formic acid concentrations up to 0.75 mM (the maximum typically used for HPLC-MS). Injections were made at 2-min intervals, 10 injections could be performed before the column was backflushed, and no ricin A chain was observed in the column effluent. This assay would also be useful for ricin since ricin A chain did not pass through the HPLC column. With minor modifications to this system, the assay should provide rapid, sensitive, selective, and quantitative assessment of the activity of most ribosome-inactivating proteins. In addition, further chromatographic and mass spectrometric improvements could reduce sample requirements and analysis times. 相似文献
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Angela B. Brueggemann Beth Mbesu Muroki Benard W. Kulohoma Angela Karani Eva Wanjiru Susan Morpeth Tatu Kamau Shahnaaz Sharif J. Anthony G. Scott 《PloS one》2013,8(11)