Salmonella sRNAs drive the decision between active stress resistance and persister cell dormancy

细菌持久性细胞代谢相对不活跃，能够应对长期的环境压力，对抗生素的耐受性相对较强。该项目旨在研究导致持久性细胞形成的过程，因为更好地了解这些过程可以显著提高我们应对诸如抗生素耐药性、食源性疾病暴发和农业疾病等社会挑战的能力。此外，该项目还为学生提供微生物学、分子生物学和计算遗传学/生物信息学的跨学科培训机会。当地高中学生将通过两个单独的举措直接受益于这个项目。值得注意的是，这些努力旨在提高代表性不足的少数民族学生对生物学和其他STEM领域的兴趣和入学率。受短期碳饥饿的沙门氏菌的sRNA谱与长期饥饿期间的sRNA谱高度不同。同样，高度不同的sRNA谱与初始和延长的细胞干燥有关。相反，在经受短时间的碳饥饿和干燥的细胞中表达的sRNAs之间，以及在长时间的干燥和长期的碳饥饿中表达的sRNAs之间，已经观察到显著的重叠。此外，在短时间应激暴露中通常诱导的几种sRNAs是通过RNA聚合酶（RNAP） sigma亚基RpoS转录的启动子表达的。相反，在长期暴露中通常诱导的许多sRNAs是由备选sigma亚基RpoE靶向的启动子表达的。综上所述，这些发现表明：在沙门氏菌中，选择性RNAP sigma亚基选择和随后不同sRNAs的表达驱动了主动抗逆性和持久性形成之间的决定。在此背景下，本项目概述的工作具有重要意义，因为它将采用一系列遗传操作和转录组学分析来表征替代sigma亚基和特定sRNAs在驱动主动抗逆性和持久性形成之间的决定中的新的重要作用。除了描述驱动主动抗逆性和持久形成之间决定的分子开关之外，这项工作测试的中心模型——通过指导抑制对立sigma因子的不同sRNAs组的转录，替代sigma因子相互竞争——很可能构成原核细胞sigma分子开关调节的一般机制，并暗示一系列附加过程。因此，本研究将探索一种新的、系统水平的全球原核转录组重编程调控机制，这可能会促进我们对驱动微生物应激反应的分子机制的基本认识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Bacterial persister cells are relatively inactive metabolically, able to cope with long-term environmental stress and are relatively tolerant of antibiotics. This project aims to study the processes that lead to persister cell formation, as a better understanding of these processes could significantly improve our ability to address societal challenges such as antibiotic resistance, foodborne illness outbreaks, and agricultural diseases. In addition, this project provides interdisciplinary student training opportunities in microbiology, molecular biology, and computational genetics/bioinformatics. Local high school students will directly benefit from this project through two separate initiatives. Notably, these efforts are intended to increase underrepresented minority student interest and enrollment in biology and other STEM fields. The sRNA profile of Salmonella subjected to short term carbon starvation is highly distinct from that seen during prolonged starvation. Similarly, highly distinct sRNA profiles are associated with initial and prolonged cellular desiccation. In contrast, significant overlaps between the sRNAs expressed in cells subjected to short durations of carbon starvation and desiccation, as well as significant overlaps between the sRNAs expressed during prolonged desiccation and long-term carbon starvation have been observed. Furthermore, several of the sRNAs commonly induced during short duration stress exposures are expressed from promoters transcribed via the RNA polymerase (RNAP) sigma subunit RpoS. Conversely, many of the sRNAs commonly induced during long term exposures are expressed from promoters targeted by the alternative sigma subunit RpoE. Together, these findings suggest the following: alternative RNAP sigma subunit selection and consequent expression of distinct sets of sRNAs drive the decision between active stress resistance and persister formation in Salmonella. Against this background, the work outlined for this project is significant, as it will employ an array of genetic manipulations and transcriptomic assays to characterize new, essential roles for alternative sigma subunits and specific sRNAs in driving the decision between active stress resistance and persister formation. Beyond characterizing the molecular switch driving the decision between active stress resistance and persister formation, the central model tested by this work-alternative sigma factors compete with one another through directing the transcription of distinct sets of sRNAs that inhibit opposing sigma factors-may well constitute a general mechanism of prokaryotic sigma molecular switch regulation with implications for an array of additional processes. As such, the work performed in this study will explore a novel, systems-level regulatory mechanism for global prokaryotic transcriptome reprogramming, which might advance our basic knowledge of the molecular mechanisms driving microbial stress responses.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.