Department of Analytical Biochemistry, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, 30-387 Krakow, Poland.
Department of Microbiology, Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University in Krakow, 30-387 Krakow, Poland.
Int J Mol Sci. 2022 Jun 9;23(12):6443. doi: 10.3390/ijms23126443.
Whilst a large number of regulatory mechanisms for gene expression have been characterised to date, transcription regulation in bacteria still remains an open subject. In clinically relevant and opportunistic pathogens, such as Staphylococcus aureus, transcription regulation is of great importance for host-pathogen interactions. In our study we investigated an operon, exclusive to staphylococci, that we name saoABC. We showed that SaoC binds to a conserved sequence motif present upstream of the saoC gene, which likely provides a negative feedback loop. We have also demonstrated that S. aureus ΔsaoB and ΔsaoC mutants display altered growth dynamics in non-optimal media; ΔsaoC exhibits decreased intracellular survival in human dermal fibroblasts, whereas ΔsaoB produces an elevated number of persisters, which is also elicited by inducible production of SaoC in ΔsaoBΔsaoC double mutant. Moreover, we have observed changes in the expression of saoABC operon genes during either depletion of the preferential carbon or the amino acid source as well as during acidification. Comparative RNA-Seq of the wild type and ΔsaoC mutant demonstrated that SaoC influences transcription of genes involved in amino acid transport and metabolism, and notably of those coding for virulence factors. Our results suggest compellingly that saoABC operon codes for a DNA-binding protein SaoC, a novel staphylococcal transcription factor, and its antagonist SaoB. We linked SaoC to the response to nutrient deficiency, a stress that has a great impact on host-pathogen interactions. That impact manifests in SaoC influence on persister formation and survival during internalisation to host cells, as well as on the expression of genes of virulence factors that may potentially result in profound alternations in the pathogenic phenotype. Investigation of such novel regulatory mechanisms is crucial for our understanding of the dynamics of interactions between pathogenic bacteria and host cells, particularly in the case of clinically relevant, opportunistic pathogens such as Staphylococcus aureus.
尽管迄今为止已经确定了大量的基因表达调控机制，但细菌的转录调控仍然是一个开放的课题。在临床相关和机会致病菌中，如金黄色葡萄球菌，转录调控对于宿主-病原体相互作用非常重要。在我们的研究中，我们研究了一个仅存在于葡萄球菌中的操纵子，我们将其命名为 saoABC。我们表明 SaoC 结合到 saoC 基因上游存在的保守序列基序上，这可能提供了一个负反馈环。我们还表明，金黄色葡萄球菌 ΔsaoB 和 ΔsaoC 突变体在非最佳培养基中显示出不同的生长动态；ΔsaoC 在人真皮成纤维细胞中的细胞内存活率降低，而 ΔsaoB 产生更多的持续存在者，这也可以通过在 ΔsaoBΔsaoC 双突变体中诱导 SaoC 的产生来引发。此外，我们观察到在耗尽优先碳源或氨基酸源以及酸化过程中 saoABC 操纵子基因的表达发生变化。野生型和 ΔsaoC 突变体的比较 RNA-Seq 表明，SaoC 影响参与氨基酸转运和代谢的基因的转录，特别是编码毒力因子的基因。我们的结果有力地表明 saoABC 操纵子编码一个 DNA 结合蛋白 SaoC，这是一种新型的葡萄球菌转录因子，及其拮抗剂 SaoB。我们将 SaoC 与营养缺乏的反应联系起来，这是对宿主-病原体相互作用有重大影响的应激源。这种影响表现在 SaoC 对形成和存活的影响持续存在者内化到宿主细胞中，以及对毒力因子基因的表达的影响，这可能导致致病表型发生深刻的改变。研究这种新型的调控机制对于我们理解致病菌与宿主细胞之间相互作用的动态至关重要，特别是对于临床相关的机会致病菌，如金黄色葡萄球菌。
