Muna Tasneem Hassan, Rutbeek Nicole R, Horne Julia, Lao Ying W, Krokhin Oleg V, Prehna Gerd
Department of Microbiology, University of Manitoba, 45 Chancellors Circle, Buller Building, Winnipeg MB, R3T 2N2, Canada.
Manitoba Centre for Proteomics and Systems Biology, University of Manitoba, 799 John Buhler Research Centre, 715 McDermot Avenue, Winnipeg MB, R3E 3P4, Canada.
Nucleic Acids Res. 2025 Jan 11;53(2). doi: 10.1093/nar/gkae1200.
Streptococcus pyogenes, or Group A Streptococcus (GAS), is a commensal bacteria and human pathogen. Central to GAS pathogenesis is the presence of prophage encoded virulence genes. The conserved phage gene for the protein paratox (Prx) is genetically linked to virulence genes, but the reason for this linkage is unknown. Prx inhibits GAS quorum sensing and natural competence by binding the transcription factor ComR. However, inhibiting ComR does not explain the virulence gene linkage. To address this, we took a mass spectrometry approach to search for other Prx interaction partners. The data demonstrates that Prx binds numerous DNA-binding proteins and transcriptional regulators. We show binding of Prx in vitro with the GAS protein Esub1 (SpyM3_0890) and the phage protein JM3 (SpyM3_1246). An Esub1:Prx complex X-ray crystal structure reveals that Esub1 and ComR possess a conserved Prx-binding helix. Computational modelling predicts that the Prx-binding helix is present in several, but not all, binding partners. Namely, JM3 lacks the Prx-binding helix. As Prx is conformationally dynamic, this suggests partner-dependent binding modes. Overall, Prx acts as a metabolic regulator of GAS to maintain the phage genome. As such, Prx maybe a direct contributor to the pathogenic conversion of GAS.
化脓性链球菌，即A组链球菌（GAS），是一种共生菌和人类病原体。GAS发病机制的核心是原噬菌体编码的毒力基因的存在。保守的噬菌体基因paratox（Prx）蛋白与毒力基因存在遗传联系，但这种联系的原因尚不清楚。Prx通过结合转录因子ComR来抑制GAS群体感应和自然感受态。然而，抑制ComR并不能解释毒力基因的联系。为了解决这个问题，我们采用了质谱分析法来寻找其他Prx相互作用伙伴。数据表明Prx与许多DNA结合蛋白和转录调节因子结合。我们展示了Prx在体外与GAS蛋白Esub1（SpyM3_0890）和噬菌体蛋白JM3（SpyM3_1246）的结合。Esub1:Prx复合物的X射线晶体结构显示Esub1和ComR具有保守的Prx结合螺旋。计算模型预测Prx结合螺旋存在于几个但不是所有的结合伙伴中。具体来说，JM3缺乏Prx结合螺旋。由于Prx在构象上是动态的，这表明存在依赖于伙伴的结合模式。总体而言，Prx作为GAS的代谢调节因子来维持噬菌体基因组。因此，Prx可能是GAS致病转化的直接促成因素。
