Development of Genetic Sensors and Circuits for Creating Novel Cellular Behaviors

PROJECT SUMMARY/ABSTRACT
Even with recent advances in synthetic biology, it remains a major challenge in developing genetic circuits
that involve multiple inputs and outputs. This is because natural genetic systems are only capable of
connecting one single chemical input to one specific promoter to control gene expression. This poses a
significant barrier in creating engineered organisms with complex signal response behavior for biomedical
applications. The long-term goals of this research team are to establish robust strategies for constructing
biological parts of genetic circuits, and to use these parts to expand researchers’ ability in engineering new
cellular functions for biomedical applications. In their recent progress, the team established a module swapping
strategy for building genetic sensors from regulators in the LacI and TetR families and they harnessed these
engineered sensors to develop several novel genetic circuits. The two directions in this proposed research
represent important steps toward the team’s long-term goals in the next five years. The first direction is to
advance the capabilities in engineering transcriptional regulators as modular biosensors. Specifically, the team
plans to 1) establish design principles of modifying regulators for enhancing their performance as biosensors
and 2) apply module swapping to a wide range of regulator families. The central hypothesis is that each
regulator within a family contains a ligand-binding module (LBM) and a DNA-binding module (DBM) for the
purpose of detecting an input signal and for interacting with a promoter, respectively; if key module-module
interactions are maintained, LBMs and DBMs from different regulators can be mixed and matched to create
hybrid regulators with new combinations of input sensing and DNA recognition properties. For their second
direction, the team proposes to harness hybrid regulators to explore novel circuit designs in various organisms,
aiming to meet emerging needs in biomedical fields. This effort includes developing cellular devices to
continuously and simultaneously monitor a range of toxic pollutants, which provides a means to assess the
intake of toxicants that are commonly found in contaminated food and water. As an Early Stage Investigator,
the PI and his team have already generated significant progress on both proposed directions, showing that
they are highly qualified to pursue the proposed projects. The contribution of this project is expected to be the
establishment of design principles for creating modular parts from regulators in many families and the
advancement in genetic circuit design and implementation. This contribution will be significant because it is
expected to release many new possibilities in circuit topologies for biomedical uses, including monitoring
devices that will be created in this program. The overall approach is innovative because it represents a new
way of using protein engineering and cellular engineering approaches to enhance public health and safety.
Therefore, the proposed work is expected to generate positive impacts at both scientific and societal levels.

Grant Number: 5R35GM142421-05
NIH Institute/Center: NIH
Principal Investigator: Tsz Yan Clement Chan