Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Ramiro de Maeztu 9, 28040, Madrid, Spain.
Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, AB25 2ZD, UK.
Sci Rep. 2022 Jul 12;12(1):11827. doi: 10.1038/s41598-022-15758-7.
The Gram-positive bacterium Streptococcus pneumoniae is a major human pathogen that shows high levels of genetic variability. The pneumococcal R6 genome harbours several gene clusters that are not present in all strains of the species. One of these clusters contains two divergent genes, pclA, which encodes a putative surface-exposed protein that contains large regions of collagen-like repeats, and spr1404 (here named pclR). PclA was shown to mediate pneumococcal adherence to host cells in vitro. In this work, we demonstrate that PclR (494 amino acids) is a transcriptional activator. It stimulates transcription of the pclA gene by binding to a specific DNA site upstream of the core promoter. In addition, we show that PclR has common features with the MgaSpn transcriptional regulator (493 amino acids), which is also encoded by the R6 genome. These proteins have high sequence similarity (60.3%), share the same organization of predicted functional domains, and generate multimeric complexes on linear double-stranded DNAs. However, on the PpclA promoter region, MgaSpn binds to a site different from the one recognized by PclR. Our results indicate that PclR and MgaSpn have similar DNA-binding properties but different DNA-binding specificities, pointing to a different regulatory role of both proteins.
革兰氏阳性细菌肺炎链球菌是一种主要的人类病原体，具有高度的遗传变异性。肺炎球菌 R6 基因组含有几个不在该物种所有菌株中存在的基因簇。其中一个簇包含两个不同的基因，pclA，它编码一种假定的表面暴露蛋白，含有大量的胶原蛋白样重复区，和 spr1404（此处命名为 pclR）。研究表明，PclA 介导肺炎球菌在体外与宿主细胞的黏附。在这项工作中，我们证明了 PclR（494 个氨基酸）是一种转录激活剂。它通过结合核心启动子上游的特定 DNA 位点来刺激 pclA 基因的转录。此外，我们还表明，PclR 具有与 MgaSpn 转录调节剂（493 个氨基酸）的共同特征，后者也由 R6 基因组编码。这些蛋白质具有很高的序列相似性（60.3%），具有相同的预测功能域组织，并在线性双链 DNA 上生成多聚体复合物。然而，在 PpclA 启动子区域，MgaSpn 结合的位点与 PclR 识别的位点不同。我们的结果表明，PclR 和 MgaSpn 具有相似的 DNA 结合特性，但具有不同的 DNA 结合特异性，表明这两种蛋白质具有不同的调节作用。
