Studies of protein synthesis in the Bacteroidia

拟杆菌属是一类重要的细菌，在包括人类在内的哺乳动物的肠道中大量存在。类杆菌属的蛋白质合成与已被充分研究的细菌（如大肠杆菌）的蛋白质合成有很大不同。该项目将揭示蛋白质在拟杆菌中产生的独特方式。在这项工作中获得的知识可能会刺激生物技术和医学的进步，特别是在抗生素开发和人类微生物组功能方面。该项目还将通过（i）为本科生和研究生提供研究培训以及（ii）为当地高中生（哥伦布公立学校）提供夏季研究机会而产生更广泛的影响。细菌翻译起始的教科书模型需要mRNA的Shine-Dalgarno（SD）序列和16 S rRNA的anti-SD（ASD）元件之间的碱基配对。在拟杆菌中，几乎所有的mRNA都缺乏SD序列，即使这些生物体的核糖体携带完整的ASD。最近的结构研究解释了这一明显矛盾的基础。16 S rRNA的3'尾被隔离在由30 S平台上的核糖体蛋白bS 21、bS 18和bS 6形成的口袋中，这是一种封闭ASD的相互作用。在SD元件存在的罕见情况下，这种相互作用允许SD用于调节目的（一种这样的情况是bS 21产生的自动调节），但通常它可能会增强这些生物体中SD较少的mRNA的起始。类杆菌核糖体还含有一种新的蛋白质bL 38，其功能尚不清楚。本计画以约氏黄杆菌为模式，探讨类杆菌蛋白质合成的独特性。具体而言，本工作将解决：（1）平台口袋如何有助于翻译启动F。johnsoniae;（2）bL 38在F. johnsoniae中bS 18缺失的核糖体是否调控多形拟杆菌（Bacteroides thetaiotaomicron）的蛋白质合成。研究结果将为不同细菌中的翻译起始、翻译调节和核糖体组装机制提供基本见解。该奖项反映了NSF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。

The Bacteroidia represent an important group of bacteria, abundant in intestinal tracts of mammals, including humans. Protein synthesis in the Bacteroidia differs substantially from that of well-studied bacteria, such as Escherichia coli. This project will uncover the unique way in which proteins are made in the Bacteroidia. The knowledge gained in this work may spur advances in biotechnology and medicine, particularly with respect to antibiotic development and human microbiome function. This project will also have broader impact by providing (i) research training for undergraduate and graduate students and (ii) summer research opportunities for local high school students (Columbus Public Schools).The textbook model of translation initiation in bacteria entails base pairing between a Shine-Dalgarno (SD) sequence of mRNA and the anti-SD (ASD) element of 16S rRNA. In Bacteroidia, virtually all mRNAs lack a SD sequence even though ribosomes of these organisms carry an intact ASD. Recent structural studies explain the basis of this apparent paradox. The 3’ tail of 16S rRNA is sequestered in a pocket formed by ribosomal proteins bS21, bS18, and bS6 on the 30S platform, an interaction which occludes the ASD. In the rare cases when SD elements are present, this interaction allows SD to be used for regulatory purposes (one such case is autoregulation of bS21 production), but generally it may enhance initiation on SD-less mRNAs in these organisms. Bacteroidia ribosomes also contain a novel protein, bL38, whose function remains unclear. This project aims to elucidate unique aspects of protein synthesis in the Bacteroidia, using Flavobacterium johnsoniae as a model. Specifically, the work will address: (1) how the platform pocket contributes to translation initiation in F. johnsoniae; (2) what role bL38 plays in F. johnsoniae, and (3) whether bS18-depleted ribosomes regulate protein synthesis in Bacteroides thetaiotaomicron, a member of order Bacteroidales. The results will provide fundamental insight on mechanisms of translation initiation, translation regulation, and ribosome assembly in diverse bacteria.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.