title: Enabling complex genetic circuits to respond to extrinsic environmental signals.
abstract: Genetic circuits have the potential to improve a broad range of metabolic engineering processes and address a variety of medical and environmental challenges. However, in order to engineer genetic circuits that can meet the needs of these real-world applications, genetic sensors that respond to relevant extrinsic and intrinsic signals must be implemented in complex genetic circuits. In this work, we construct the first AND and NAND gates that respond to temperature and pH, two signals that have relevance in a variety of real-world applications. A previously identified pH-responsive promoter and a temperature-responsive promoter were extracted from the E. coli genome, characterized, and modified to suit the needs of the genetic circuits. These promoters were combined with components of the type III secretion system in Salmonella typhimurium and used to construct a set of AND gates with up to 23-fold change. Next, an antisense RNA was integrated into the circuit architecture to invert the logic of the AND gate and generate a set of NAND gates with up to 1168-fold change. These circuits provide the first demonstration of complex pH- and temperature-responsive genetic circuits, and lay the groundwork for the use of similar circuits in real-world applications. Biotechnol. Bioeng. 2017;114: 1626-1631. © 2017 Wiley Periodicals, Inc.
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis 63130, One Brookings Dr., Box 1180, Missouri.
authors.forename: Allison
authors.initials: A
authors.lastname: Hoynes-O'Connor
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis 63130, One Brookings Dr., Box 1180, Missouri.
authors.forename: Tatenda
authors.initials: T
authors.lastname: Shopera
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis 63130, One Brookings Dr., Box 1180, Missouri.
authors.forename: Kristina
authors.initials: K
authors.lastname: Hinman
authors.affiliation: Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: John Philip
authors.initials: JP
authors.lastname: Creamer
authors.affiliation: Department of Energy, Environmental and Chemical Engineering, Washington University in St. Louis, St. Louis 63130, One Brookings Dr., Box 1180, Missouri.|Division of Biology and Biomedical Sciences, Washington University in St. Louis, St. Louis, Missouri.
authors.forename: Tae Seok
authors.identifier: 0000-0001-8373-9051
authors.initials: TS
authors.lastname: Moon
mesh_terms: D039301:Computers, Molecular; D004926:Escherichia coli / Q000235:genetics*; D053263:Gene Regulatory Networks / Q000235:genetics*; D012486:Salmonella typhimurium / Q000235:genetics*; D012815:Signal Processing, Computer-Assisted; D015398:Signal Transduction / Q000235:genetics*; D058615:Synthetic Biology / Q000379:methods; D000069296:Type III Secretion Systems / Q000235:genetics*
chemical_list: D000069296:Type III Secretion Systems
keywords: AND gate; NAND gate; genetic circuit; genetic sensor; synthetic biology