In Streptococcus mutans, SprV (SMU.2137) is a pleiotropic regulator that differentially regulates genes related to competence, mutacin production, biofilm formation, and the stress tolerance response, along with some other pathways. In this study, we established a link between SprV and an ∼67-kDa protein in the culture supernatant of strain UA159 that was later confirmed as SMU.63 by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) analysis. We discovered that SprV downregulates the transcription and translation of SMU.63. We found that the seven amino acids from the C-terminal region of SprV were also crucial for the expression of SMU.63. Deletion of smu.63 led to increased sucrose-independent biofilm formation and competence. The sprV deletion also increased biofilm formation although this could be partially attributed to the downregulation of smu.63. In an smu.63 sprV double mutant, a synergistic effect was observed in biofilm formation in contrast to effects on competence development. We found that low or excess magnesium ion repressed sprV transcription that, in turn, affected the expression of smu.63. As expected, a magnesium ion-dependent effect of competence and biofilm formation was observed in the UA159 strain. We also replicated the results of SMU.63 expression and competence in S. mutans GS5 that encodes both SprV and SMU.63 homologs and found that the GS5 strain behaves similarly to the UA159 strain, indicating that SprV’s effect is strain independent.

中文翻译：

---

变形链球菌中的SprV调节细胞外蛋白（SMU.63）的表达。

在变形链球菌中，SprV（SMU.2137）是一种多效性调节剂，可差异调节与能力，诱变素产生，生物膜形成和应激耐受性反应以及其他一些途径相关的基因。在这项研究中，我们在菌株UA159的培养上清液中建立了SprV和〜67-kDa蛋白之间的联系，后来通过基质辅助激光解吸电离-飞行时间质谱（MALDI-TOF MS）将其确认为SMU.63。 ）分析。我们发现SprV下调SMU.63的转录和翻译。我们发现，SprV C末端区域的七个氨基酸对于SMU.63的表达也至关重要。smu.63的删除导致不依赖蔗糖的生物膜形成和能力增强。的sprV缺失也增加了生物膜的形成，尽管这可能部分归因于smu.63的下调。在smu.63 sprV双突变体中，与对能力发展的影响相反，在生物膜形成中观察到了协同作用。我们发现，低或过量的镁离子会抑制sprV转录，进而影响smu.63的表达。如所预期的，在UA159菌株中观察到镁离子依赖性的能力和生物膜形成作用。我们还复制了SMU.63在变形链球菌中的表达和能力的结果 编码SprV和SMU.63同源物的GS5，发现GS5菌株的行为与UA159菌株相似，表明SprV的作用与菌株无关。