Efflux Pump Control Alters Synthetic Gene Circuit Function.
Synthetic biology aims to design new biological systems for predefined purposes, such as the controlled secretion of biofuels, pharmaceuticals, or other chemicals. Synthetic gene circuits regulating an efflux pump from the ATP-binding cassette (ABC) protein family could achieve this. However, ABC efflux pumps can also drive out intracellular inducer molecules that control the gene circuits. This will introduce an implicit feedback that could alter gene circuit function in ways that are poorly understood. Here, we used two synthetic gene circuits inducible by tetracycline family molecules to regulate the expression of a yeast ABC pump (Pdr5p) that pumps out the inducer. Pdr5p altered the dose-responses of the original gene circuits substantially in Saccharomyces cerevisiae. While one aspect of the change could be attributed to the efflux pumping function of Pdr5p, another aspect remained unexplained. Quantitative modeling indicated that reduced regulator gene expression in addition to efflux pump function could fully explain the altered dose-responses. These predictions were validated experimentally. Overall, we highlight how efflux pumps can alter gene circuit dynamics and demonstrate the utility of mathematical modeling in understanding synthetic gene circuit function in new circumstances.
Department of Systems Biology, The University of Texas MD Anderson Cancer Center , Unit 950, 7435 Fannin Street, Houston, Texas 77054, United States.
Junchen
J
Diao
The Louis and Beatrice Laufer Center for Physical & Quantitative Biology, Stony Brook University , 115C Laufer Center, Z-5252, Stony Brook, New York 11794, United States.
Daniel A
DA
Charlebois
Department of Systems Biology, The University of Texas MD Anderson Cancer Center , Unit 950, 7435 Fannin Street, Houston, Texas 77054, United States.|School of Biomedicine, Far Eastern Federal University , 8 Sukhanova Street, Vladivostok, 690950, Russia.
Dmitry
D
Nevozhay
Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences , Temesvári krt. 62., H-6726 Szeged, Hungary.
Zoltán
Z
Bódi
Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences , Temesvári krt. 62., H-6726 Szeged, Hungary.
Csaba
C
Pál
Department of Systems Biology, The University of Texas MD Anderson Cancer Center , Unit 950, 7435 Fannin Street, Houston, Texas 77054, United States.|The Louis and Beatrice Laufer Center for Physical & Quantitative Biology, Stony Brook University , 115C Laufer Center, Z-5252, Stony Brook, New York 11794, United States.|Department of Biomedical Engineering, Z-5281, Stony Brook University , Stony Brook, New York 11794, United States.
Gábor
G
Balázsi
D018528:ATP-Binding Cassette Transporters / Q000235:genetics* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004318:Doxycycline / Q000008:administration & dosage / Q000494:pharmacology; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects; D053263:Gene Regulatory Networks; D005813:Genes, Synthetic; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D008962:Models, Theoretical; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D013752:Tetracycline / Q000494:pharmacology
D018528:ATP-Binding Cassette Transporters; C092438:PDR5 protein, S cerevisiae; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins; D049452:Green Fluorescent Proteins; D013752:Tetracycline; D004318:Doxycycline
efflux pump; feedback; stochastic simulation; synthetic gene circuit