Studies of protein synthesis in the Bacteroidia

杆形虫是一类重要的细菌，广泛存在于包括人类在内的哺乳动物肠道中。杆菌的蛋白质合成与研究很好的细菌，如大肠杆菌的蛋白质合成有很大的不同。这个项目将揭示杆菌中蛋白质制造的独特方式。在这项工作中获得的知识可能会促进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。该项目还将产生更广泛的影响，为本科生和研究生提供(I)本科生和研究生的研究培训，以及(Ii)为当地高中生(哥伦布公立学校)提供暑期研究机会。细菌翻译启动的教科书模型需要将Shine-Dalgarno(SD)序列与16S rRNA的抗SD(ASD)元件之间的碱基配对。在杆形虫中，几乎所有的mRNAs都缺乏SD序列，即使这些生物的核糖体携带完整的ASD。最近的结构研究解释了这一明显悖论的基础。16S rRNA的3‘尾巴被隔离在30S平台上由核糖体蛋白bS21、bS18和bS6形成的口袋中，这种相互作用阻断了ASD。在极少数情况下，当SD元件存在时，这种相互作用允许SD用于调节目的(其中一种情况是bS21生产的自动调节)，但通常它可能增强这些生物中无SD的mRNAs的启动。杆菌核糖体还含有一种新的蛋白质bL38，其功能尚不清楚。本项目以强生黄杆菌为模型，旨在阐明杆菌中蛋白质合成的独特方面。具体地说，这项工作将研究：(1)平台口袋如何促进强氏杆菌的翻译起始；(2)bL38在强氏杆菌中扮演什么角色；以及(3)bS18缺失的核糖体是否调节拟杆菌目的蛋白合成。这一结果将为不同细菌中的翻译启动、翻译调控和核糖体组装机制提供基本的见解。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.