Principles for Systematic Optimization of an Orthogonal Translation System with Enhanced Biological Tolerance

Over the past twenty years, the development of orthogonal biological systems has sparked a revolution in our ability to study cellular physiology. Orthogonal translation systems (OTSs) enable site-specific incorporation of hundreds of non-standard amino acids, offering unprecedented access to the study of cellular mechanisms modulated by post-translational modifications (e.g. protein phosphorylation). Although development of phosphoserine-OTSs (pSerOTS) has been significant, little work has focused on the biology of OTS development and utilization. To better understand the impact of OTSs on host physiology, we utilize pSerOTS as a model to systematically explore the extent to which OTS components interact with Escherichia coli. Using this information, we constructed pSerOTS variants designed to enhance OTS orthogonality by minimizing interactions with host processes and decreasing stress response activation. Our expanded understanding of OTS:host interactions enables informed OTS design practices which minimize the negative impact of OTSs while improving OTS performance across a range of experimental settings.