Unknown,Transcriptomics,Genomics,Proteomics

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Activity of SigB Modulates Virulence Gene Expression in a Murine Staphylococcus aureus Infection Model but Does Not Influence the Host Kidney Gene Expression

ABSTRACT: Background. Infections caused by Staphylococcus aureus are associated with significant morbidity and mortality and are an increasing threat not only in hospital settings. The expression of the staphylococcal virulence factor repertoire is known to be affected by the alternative sigma factor B (SigB). However, its impact during infection still is a matter of debate. Methods. Kidney tissue of controls or mice infected with S. aureus HG001 or its isogenic sigB mutant was analyzed by transcriptome profiling to monitor the host response, and additionally expression of selected S. aureus genes was monitored by RT-qPCR. Results. Direct transcript analysis by RT-qPCR revealed significant SigB activity in all mice infected with the wild type strain (WT), but not in its isogenic sigB mutant (p<0.0001). Despite a clear cut difference in the SigB-dependent transcription pattern of virulence genes (clfA, aur, and hla), the host reaction to infection (either WT or sigB mutant) was almost identical. Conclusions. Despite its significant activity in vivo, loss of SigB did not have an effect on the outcome of infection as well as on murine kidney gene expression pattern. Thus, these data support the role of SigB as virulence modulator rather than being a virulence determinant by itself. Murine kidney gene expression pattern of 3 groups were compared: 1) after infection with S. aureus HG001 (wild type); 2) after infection with S. aureus HG001 ΔsigB; 3) sham control (injection of physiological saline solution). The infection was performed twice (2 biological replicates), and the array analysis included 4 or 5 mice (independent samples) per group. In total, the study consisted of 24 arrays.

ORGANISM(S): Mus musculus

SUBMITTER: Maren Depke

PROVIDER: E-GEOD-28540 | biostudies-arrayexpress |

REPOSITORIES: biostudies-arrayexpress

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The alternative sigma factor B modulates virulence gene expression in a murine Staphylococcus aureus infection model but does not influence kidney gene expression pattern of the host.

Depke Maren M Burian Marc M Schäfer Tina T Bröker Barbara M BM Ohlsen Knut K Völker Uwe U

International journal of medical microbiology : IJMM 20111022 1

Infections caused by Staphylococcus aureus are associated with significant morbidity and mortality and are an increasing threat not only in hospital settings. The expression of the staphylococcal virulence factor repertoire is known to be affected by the alternative sigma factor B (SigB). However, its impact during infection still is a matter of debate. Kidney tissues of controls or mice infected with S. aureus HG001 or its isogenic sigB mutant were analyzed by transcriptome profiling to monitor ...[more]

PMID: 22019488

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Project description:The Gram-positive pathogenic bacterium Staphylococcus aureus permanently colonizes the nasal mucosa in about 30% of the healthy population. However, as an opportunistic pathogen, S. aureus can also cause a variety of diseases, the treatment of which is becoming increasingly difficult due to antibiotic resistance. Adaptation to changing environmental conditions during colonization and infection of the host requires precise regulation of the expression of genes for virulence factors and metabolic functions. The host conditions essentially include low iron availability, with the majority of iron in the human organism being present intracellularly in the form of haemoglobin. Therefore, S. aureus has various adaptive mechanisms, in particular iron uptake systems, which are regulated by the global iron uptake regulator Fur (ferric-uptake regulator). Iron deficiency conditions lead to the derepression of Fur-dependent genes. In many bacteria, these genes also include regulatory RNAs (small regulatory RNAs, sRNAs), which mediate an iron-sparing response by inhibiting the synthesis of non-essential iron-containing proteins. A Fur-dependent sRNA (S596) was identified in a transcriptome analysis of S. aureus. In a study by Coronel-Tellez et al. (2022) it was shown that S596/IsrR (“iron sparing response regulator”) is necessary for the virulence of S. aureus. In the presented secretome analysis, the S. aureus HG001 wild type (WT) was compared with an isogenic isrR mutant (ΔisrR) under iron-limiting conditions and a constitutively isrR-expressing strain (HG001 pJLisrR) with an empty vector control (HG001 pJLctrl) under iron-rich conditions as well as corresponding sae mutant (Δsae) strains. Culture supernatants were collected in the exponential and stationary growth phases and extracellular proteins were subsequently analyzed by mass spectrometry. Statistical data analysis was performed to identify proteins with significantly altered amounts between the respective strains. We demonstrate that IsrR positively influences the protein levels of numerous virulence factors which in particular belong to the Sae regulon.