Synthetic Biology: Construction of Genetic Circuits for Engineering Applications

Abstract

Synthetic biology is the design and construction of new biological parts, devices, and systems, and the re-design of existing, natural biological systems for useful purposes. It is a challenge for constructing functional synthetic circuits and getting them to work in the host cell together. In general, combining disparate components requires the tuning of biochemical parameters such as affinities or rate constants, which are often difficult to implement in biological circuits. In this review, we discuss how can one design an operating circuit given these limitations? Several strategies can be applied. First, the use of tunable elements, such as transcription factors derived from repressors, allows external control over some parameters. A second strategy is to use robust circuit designs that are inherently insensitive to unknown or variable parameters. Third, some directed evolution methods can be applied to optimize parameters. System control theories and simulation tools need to be developed to guide robust biological circuit design, and then a design process that consists of selecting the appropriate DNA components and genetically modifying the existing DNA components using directed evolution is employed to engineer genetic circuits until the desired functions is achieved to program cell behaviors.