RUI: Evolution of Bacterial Asparaginyl-tRNA Synthesis

这项研究的目的是了解为什么某些细菌采用两种不同的途径来制备用于蛋白质合成的氨基酸天冬酰胺。 这些结果将为这些替代途径的进化起源以及它们如何赋予在不同自然环境中生长的细菌适应性生理优势提供见解，即，与哺乳动物宿主体内的对比 本科生，包括代表性不足的少数民族成员，将通过该项目接受实验室研究方面的培训。 培训的影响将通过在科学会议上介绍研究，同行评审文章的学生合著以及未来学生在劳动力和研究生课程中的安置来衡量。此外，该项目将允许从研究中产生的研究被整合到实验生物化学实验室课程，培养更多的本科生在假设驱动的生物化学研究。 为了扩大科学素养并留住更多来自STEM学科代表性不足的少数民族的学生，该项目将向中学生提供外联服务。 将遗传信息翻译成蛋白质的氨基酸序列对细胞生命至关重要。 该过程的保真度取决于正确的衔接分子氨酰-tRNA的形成。在细胞中，将氨基酸连接到正确的tRNA上主要是通过氨酰-tRNA合成酶进行的。每个tRNA合成酶都对一种氨基酸具有特异性，并且只将氨基酸连接到特定的tRNA分子上。然而，在许多细菌基因组中，直接将天冬酰胺连接到其同源tRNA的天冬酰胺酰-tRNA合成酶不被编码。相反，这些生物通过间接的两步途径在tRNA上合成天冬酰胺。首先，他们使用一种非识别性的氨酰-tRNA合成酶用天冬氨酸氨酰化tRNA。然后，tRNA结合的Asp被酰胺转移酶GatCAB酰胺化以形成天冬酰胺酰-tRNA。许多细菌，包括枯草芽孢杆菌和耐盐芽孢杆菌，编码天冬酰胺酰-tRNA合成的两种途径。编码这两种途径的细菌的一个子集获得了古细菌的非歧视性的N-乙酰-tRNA合成酶，用于tRNA依赖的天冬酰胺生物合成。该项目的目标是使用生物化学和微生物遗传学方法来阐明为什么这么多细菌保留天冬酰胺酰-tRNA形成的两种途径，以及为什么某些细菌获得了用于该任务的古细菌非歧视性天冬酰胺酰-tRNA合成酶。预计结果将揭示对蛋白质合成准确性至关重要的过程的演变。

The goal of this research is to understand why certain bacteria employ two distinct routes for preparing the amino acid asparagine for protein synthesis. The results will provide insights into the evolutionary origin of these alternate pathways and how they may confer adaptive physiological advantages to bacteria growing in different natural environments, i.e., in soil versus inside a mammalian host. Undergraduate students, including members of underrepresented minorities, will be trained in laboratory research through the project. The impact of the training will be measured by the presentation of the research at scientific meetings, student co-authorship of peer reviewed articles, and future student placement in the workforce and in graduate programs. In addition, the project will allow studies arising from the research to be integrated into an experimental biochemistry laboratory course, training additional undergraduate students in hypothesis driven biochemical research. To expand scientific literacy and retain more students from underrepresented minorities in STEM disciplines, the project will provide outreach to middle school students. Translation of a genetic message into the amino acid sequence of a protein is essential for cellular life. The fidelity of the process is dependent on the formation of the correct adaptor molecules, aminoacyl-tRNAs. Attaching an amino acid to the right tRNA is carried out in cells primarily by aminoacyl-tRNA synthetases. Each tRNA synthetase is specific for one amino acid and only ligates the amino acid onto a certain set of tRNA molecules. However, in many bacterial genomes asparaginyl-tRNA synthetase that directly attaches asparagine to its cognate tRNA is not encoded. Instead these organisms synthesize asparagine on the tRNA via an indirect two-step pathway. First they use a non-discriminating aspartyl-tRNA synthetase to aminoacylate tRNA with aspartate. The tRNA-bound Asp is then amidated by the amidotransferase GatCAB to form asparaginyl-tRNA. A number of bacteria, including Bacillus subtilis and Bacillus halodurans, encode both routes for asparaginyl-tRNA synthesis. A subset of bacteria encoding both routes acquired an archaeal non-discriminating aspartyl-tRNA synthetase for tRNA-dependent asparagine biosynthesis. The objectives of this project are to use biochemical and microbial genetic approaches to elucidate why so many bacteria retain both routes for asparaginyl-tRNA formation and why certain bacteria acquired an archaeal non-discriminating aspartyl-tRNA synthetase for the task. Results are expected to shed light on the evolution of a process that is crucial for the accuracy of protein synthesis.