Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA.
Department of Microbiology and Molecular Genetics, McGovern Medical School, University of Texas Health Science Center, Houston, Texas, USA.
J Bacteriol. 2020 Aug 25;202(18). doi: 10.1128/JB.00245-20.
Posttranscriptional gene regulation often involves RNA-binding proteins that modulate mRNA translation and/or stability either directly through protein-RNA interactions or indirectly by facilitating the annealing of small regulatory RNAs (sRNAs). The human pathogen D39 (pneumococcus) does not encode homologs to RNA-binding proteins known to be involved in promoting sRNA stability and function, such as Hfq or ProQ, even though it contains genes for at least 112 sRNAs. However, the pneumococcal genome contains genes for other RNA-binding proteins, including at least six S1 domain proteins: ribosomal protein S1 (), polynucleotide phosphorylase (), RNase R (), and three proteins with unknown functions. Here, we characterize the function of one of these conserved, yet uncharacterized, S1 domain proteins, SPD_1366, which we have renamed CvfD (onserved irulence actor ), since loss of the protein results in attenuation of virulence in a murine pneumonia model. We report that deletion of impacts the expression of 144 transcripts, including the operon, encoding phosphate transport system 1 in We further show that CvfD posttranscriptionally regulates the PhoU2 master regulator of the pneumococcal dual-phosphate transport system by binding mRNA and impacting PhoU2 translation. CvfD not only controls expression of phosphate transporter genes but also functions as a pleiotropic regulator that impacts cold sensitivity and the expression of sRNAs and genes involved in diverse cellular functions, including manganese uptake and zinc efflux. Together, our data show that CvfD exerts a broad impact on pneumococcal physiology and virulence, partly by posttranscriptional gene regulation. Recent advances have led to the identification of numerous sRNAs in the major human respiratory pathogen However, little is known about the functions of most sRNAs or RNA-binding proteins involved in RNA biology in pneumococcus. In this paper, we characterize the phenotypes and one target of the S1 domain RNA-binding protein CvfD, a homolog of general stress protein 13 identified, but not extensively characterized, in other species. Pneumococcal CvfD is a broadly pleiotropic regulator, whose absence results in misregulation of divalent cation homeostasis, reduced translation of the PhoU2 master regulator of phosphate uptake, altered metabolism and sRNA amounts, cold sensitivity, and attenuation of virulence. These findings underscore the critical roles of RNA biology in pneumococcal physiology and virulence.
转录后基因调控通常涉及 RNA 结合蛋白，这些蛋白通过直接的蛋白-RNA 相互作用或通过促进小调控 RNA（sRNA）的退火来调节 mRNA 翻译和/或稳定性。人类病原体 D39（肺炎球菌）不编码已知参与促进 sRNA 稳定性和功能的 RNA 结合蛋白的同源物，例如 Hfq 或 ProQ，尽管它含有至少 112 个 sRNA 的基因。然而，肺炎球菌基因组包含其他 RNA 结合蛋白的基因，包括至少六个 S1 结构域蛋白：核糖体蛋白 S1 ()、多核苷酸磷酸化酶 ()、RNase R () 和三个具有未知功能的蛋白质。在这里，我们描述了这些保守但尚未表征的 S1 结构域蛋白之一 SPD_1366 的功能，我们将其重新命名为 CvfD（保守毒力因子），因为该蛋白的缺失导致小鼠肺炎模型中毒力减弱。我们报告说，缺失 会影响 144 个转录物的表达，包括编码磷酸盐转运系统 1 的 操纵子 在 中。我们进一步表明，CvfD 通过结合 mRNA 并影响 PhoU2 双磷酸盐转运系统的主调控因子 PhoU2 的翻译来转录后调控 PhoU2。CvfD 不仅控制磷酸盐转运基因的表达，还作为一种多效调节因子发挥作用，影响冷敏感性和 sRNA 以及涉及多种细胞功能（包括锰摄取和锌外排）的基因的表达。总之，我们的数据表明 CvfD 对肺炎球菌的生理和毒力有广泛的影响，部分原因是通过转录后基因调控。最近的进展导致在主要的人类呼吸道病原体 中鉴定出许多 sRNA，但对大多数 sRNA 或参与 RNA 生物学的 RNA 结合蛋白的功能知之甚少。在本文中，我们描述了 S1 结构域 RNA 结合蛋白 CvfD 的表型和一个靶标，CvfD 是一般应激蛋白 13 的同源物，在其他 物种中已被鉴定出来，但尚未得到广泛表征。肺炎球菌 CvfD 是一种广泛的多效调节因子，其缺失导致二价阳离子稳态失调、磷酸盐摄取的 PhoU2 主调控因子翻译减少、代谢和 sRNA 数量改变、冷敏感性以及毒力减弱。这些发现强调了 RNA 生物学在肺炎球菌生理和毒力中的关键作用。
