title: Modular, multi-input transcriptional logic gating with orthogonal LacI/GalR family chimeras.
abstract: In prokaryotes, the construction of synthetic, multi-input promoters is constrained by the number of transcription factors that can simultaneously regulate a single promoter. This fundamental engineering constraint is an obstacle to synthetic biologists because it limits the computational capacity of engineered gene circuits. Here, we demonstrate that complex multi-input transcriptional logic gating can be achieved through the use of ligand-inducible chimeric transcription factors assembled from the LacI/GalR family. These modular chimeras each contain a ligand-binding domain and a DNA-binding domain, both of which are chosen from a library of possibilities. When two or more chimeras have the same DNA-binding domain, they independently and simultaneously regulate any promoter containing the appropriate operator site. In this manner, simple transcriptional AND gating is possible through the combination of two chimeras, and multiple-input AND gating is possible with the simultaneous use of three or even four chimeras. Furthermore, we demonstrate that orthogonal DNA-binding domains and their cognate operators allow the coexpression of multiple, orthogonal AND gates. Altogether, this work provides synthetic biologists with novel, ligand-inducible logic gates and greatly expands the possibilities for engineering complex synthetic gene circuits.
authors.affiliation: Department of Biochemistry & Cell Biology, Rice University , Houston, Texas 77005, United States.
authors.forename: David L
authors.initials: DL
authors.lastname: Shis
authors.forename: Faiza
authors.initials: F
authors.lastname: Hussain
authors.forename: Sarah
authors.initials: S
authors.lastname: Meinhardt
authors.forename: Liskin
authors.initials: L
authors.lastname: Swint-Kruse
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Bennett
mesh_terms: D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics*; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D007544:Isopropyl Thiogalactoside / Q000494:pharmacology; D056968:Lac Repressors / Q000235:genetics*; D008024:Ligands; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D014158:Transcription, Genetic / Q000187:drug effects; D000097573:Red Fluorescent Protein
chemical_list: D029968:Escherichia coli Proteins; D049452:Green Fluorescent Proteins; D007544:Isopropyl Thiogalactoside; D056968:Lac Repressors; D008024:Ligands; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D000097573:Red Fluorescent Protein; C050993:Galactose repressor proteins; C539064:LacI protein, E coli