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Global transcriptional analysis of the obligate intracellular bacteria Rickettsia conorii

ABSTRACT: Rickettsia conorii are obligate intracellular bacteria responsible for the Mediterranean spotted fever. Their adaptation to highly divergent environments ranging from the arthropod vector to the human beings is essential to survival and virulence. Through a combination of total RNA purification and random prokaryotic cDNA amplification, we successfully analyzed transcription profiles by microarrays starting from 100 ng of R. conorii RNA. Real-time quantitative PCR results performed on unpurified total RNA was consistent with microarray measurements. Here, from the selected targets spotted on our microarray, we showed that in R. conorii, nutrient stress is accompanied by over-expression of the virB operon. Regulation of these genes could be mediated by the stringent response through ppGpp, consistent with the observed up-regulation of spoT and gmk. Exposure of R. conorii to a nutrient stress paradoxically reduced the expression of both GroEL and its transcriptional regulator RpoH. This shows that the over-expression of this chaperonin is a part of the natural life of intracellular growing rickettsiae. Our findings also evidenced that, unexpectedly, many atypical sequences, including small-size split genes, ORFans genes and highly conserved intergenic regions contains expressed sequences that are differentially regulated. The notable deficiency of transcriptional regulators within R. conorii genome does not reflect its incapability to undergo transcriptional changes but rather the existence of an alternative adaptation strategy. Keywords: Global transcriptional analysis

ORGANISM(S): Rickettsia conorii

PROVIDER: GSE5201 | GEO | 2006/07/06

SECONDARY ACCESSION(S): PRJNA96563

REPOSITORIES: GEO

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