TY  - JOUR
A1  - Karunakaran, Karthika
A1  - Mehlitz, Adrian
A1  - Rudel, Thomas
T1  - Evolutionary conservation of infection-induced cell death inhibition among Chlamydiales
N2  - Control of host cell death is of paramount importance for the survival and replication of obligate intracellular bacteria. Among these, human pathogenic Chlamydia induces the inhibition of apoptosis in a variety of different host cells by directly interfering with cell death signaling. However, the evolutionary conservation of cell death regulation has not been investigated in the order Chlamydiales, which also includes Chlamydia-like organisms with a broader host spectrum. Here, we investigated the apoptotic response of human cells infected with the Chlamydia-like organism Simkania negevensis (Sn). Simkania infected cells exhibited strong resistance to apoptosis induced by intrinsic stress or by the activation of cell death receptors. Apoptotic signaling was blocked upstream of mitochondria since Bax translocation, Bax and Bak oligomerisation and cytochrome c release were absent in these cells. Infected cells turned on pro-survival pathways like cellular Inhibitor of Apoptosis Protein 2 (cIAP-2) and the Akt/PI3K pathway. Blocking any of these inhibitory pathways sensitized infected host cell towards apoptosis induction, demonstrating their role in infection-induced apoptosis resistance. Our data support the hypothesis of evolutionary conserved signaling pathways to apoptosis resistance as common denominators in the order Chlamydiales.
KW  - Chlamydiales
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-68978
ER  - 
TY  - JOUR
A1  - Albrecht, Marco
A1  - Sharma, Cynthia M.
A1  - Dittrich, Marcus T.
A1  - Müller, Tobias
A1  - Reinhardt, Richard
A1  - Vogel, Jörg
A1  - Rudel, Thomas
T1  - The Transcriptional Landscape of Chlamydia pneumoniae
N2  - Background: Gene function analysis of the obligate intracellular bacterium Chlamydia pneumoniae is hampered by the facts that this organism is inaccessible to genetic manipulations and not cultivable outside the host. The genomes of several strains have been sequenced; however, very little information is available on the gene structure and transcriptome of C. pneumoniae. Results: Using a differential RNA-sequencing approach with specific enrichment of primary transcripts, we defined the transcriptome of purified elementary bodies and reticulate bodies of C. pneumoniae strain CWL-029; 565 transcriptional start sites of annotated genes and novel transcripts were mapped. Analysis of adjacent genes for cotranscription revealed 246 polycistronic transcripts. In total, a distinct transcription start site or an affiliation to an operon could be assigned to 862 out of 1,074 annotated protein coding genes. Semi-quantitative analysis of mapped cDNA reads revealed significant differences for 288 genes in the RNA levels of genes isolated from elementary bodies and reticulate bodies. We have identified and in part confirmed 75 novel putative non-coding RNAs. The detailed map of transcription start sites at single nucleotide resolution allowed for the first time a comprehensive and saturating analysis of promoter consensus sequences in Chlamydia. Conclusions: The precise transcriptional landscape as a complement to the genome sequence will provide new insights into the organization, control and function of genes. Novel non-coding RNAs and identified common promoter motifs will help to understand gene regulation of this important human pathogen.
KW  - Chlamydia pneumoniae
Y1  - 2011
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-69116
ER  -