TY  - JOUR
A1  - Wippel, Carolin
A1  - Förtsch, Christina
A1  - Hupp, Sabrina
A1  - Maier, Elke
A1  - Benz, Roland
A1  - Ma, Jiangtao
A1  - Mitchell, Timothy J
A1  - Iliev, Asparouh I
T1  - Extracellular Calcium Reduction Strongly Increases the Lytic Capacity of Pneumolysin From Streptococcus Pneumoniae in Brain Tissue
JF  - The Journal of Infectious Diseases
N2  - Background

Streptococcus pneumoniae causes serious diseases such as pneumonia and meningitis. Its major pathogenic factor is the cholesterol-dependent cytolysin pneumolysin, which produces lytic pores at high concentrations. At low concentrations, it has other effects, including induction of apoptosis. Many cellular effects of pneumolysin appear to be calcium dependent.

Methods 

Live imaging of primary mouse astroglia exposed to sublytic amounts of pneumolysin at various concentrations of extracellular calcium was used to measure changes in cellular permeability (as judged by lactate dehydrogenase release and propidium iodide chromatin staining). Individual pore properties were analyzed by conductance across artificial lipid bilayer. Tissue toxicity was studied in continuously oxygenated acute brain slices.

Results 

The reduction of extracellular calcium increased the lytic capacity of the toxin due to increased membrane binding. Reduction of calcium did not influence the conductance properties of individual toxin pores. In acute cortical brain slices, the reduction of extracellular calcium from 2 to 1 mM conferred lytic activity to pathophysiologically relevant nonlytic concentrations of pneumolysin.

Conclusions 

Reduction of extracellular calcium strongly enhanced the lytic capacity of pneumolysin due to increased membrane binding. Thus, extracellular calcium concentration should be considered as a factor of primary importance for the course of pneumococcal meningitis. "
KW  - bacteria
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-139356
VL  - 204
IS  - 6
ER  - 
TY  - JOUR
A1  - Schmidtke, Cornelius
A1  - Findeiß, Sven
A1  - Sharma, Cynthia M.
A1  - Kuhfuss, Juliane
A1  - Hoffmann, Steve
A1  - Vogel, Jörg
A1  - Stadler, Peter F.
A1  - Bonas, Ulla
T1  - Genome-wide transcriptome analysis of the plant pathogen Xanthomonas identifies sRNAs with putative virulence functions
JF  - Nucleic Acids Research
N2  - The Gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria (Xcv) is an important model to elucidate the mechanisms involved in the interaction with the host. To gain insight into the transcriptome of the Xcv strain 85-10, we took a differential RNA sequencing (dRNA-seq) approach. Using a novel method to automatically generate comprehensive transcription start site (TSS) maps we report 1421 putative TSSs in the Xcv genome. Genes in Xcv exhibit a poorly conserved -10 promoter element and no consensus Shine-Dalgarno sequence. Moreover, 14% of all mRNAs are leaderless and 13% of them have unusually long 5'-UTRs. Northern blot analyses confirmed 16 intergenic small RNAs and seven cis-encoded antisense RNAs in Xcv. Expression of eight intergenic transcripts was controlled by HrpG and HrpX, key regulators of the Xcv type III secretion system. More detailed characterization identified sX12 as a small RNA that controls virulence of Xcv by affecting the interaction of the pathogen and its host plants. The transcriptional landscape of Xcv is unexpectedly complex, featuring abundant antisense transcripts, alternative TSSs and clade-specific small RNAs.
KW  - SUBSP carotovora
KW  - regulatory RNA
KW  - gene-cluster
KW  - campestris PV vesicatoria
KW  - escherichia coli
KW  - determines pathgenicity
KW  - hypersensitive response
KW  - ralstonia solanacearum
KW  - extracellular enzymes
KW  - secretion systems
KW  - transcription initiation site
KW  - RNA sequence analyses
KW  - messanger RNA
KW  - plants
KW  - libraries
KW  - genome
KW  - genes
KW  - gene expression profiling
KW  - genetic transcription
KW  - northern blotting
KW  - untranslated regions
KW  - xanthomonas
KW  - xanthomonas campestris
KW  - bacteria
KW  - virulence
KW  - pathogenetic organism
KW  - RNA
KW  - small RNA
KW  - pathogenicity
KW  - type III secretion system pathways
KW  - maps
KW  - consesus
KW  - host (organism)
KW  - type III protein secretion system complex
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-131781
VL  - 40
IS  - 5
SP  - 2020
EP  - 2031
ER  -