Rapid generation of CRISPR/dCas9-regulated, orthogonally repressible hybrid T7-lac promoters for modular, tuneable control of metabolic pathway fluxes in E. coli

Authors
Cress, B.
Jones, J.
Daniel, K.
Leitz, Q.
Englaender, J.
Collins, S.
Linhardt, Robert J.
Koffas, M.
ORCID
https://orcid.org/0000-0003-2219-5833
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Issue Date
2016
Keywords
Biology , Chemistry and chemical biology , Chemical and biological engineering , Biomedical engineering
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Terms of Use
Attribution 3.0 United States
CC BY : this license allows reusers to distribute, remix, adapt, and build upon the material in any medium or format, so long as attribution is given to the creator. The license allows for commercial use. Credit must be given to the authors and the original work must be properly cited.
Full Citation
Rapid generation of CRISPR/dCas9-regulated, orthogonally repressible hybrid T7-lac promoters for modular, tuneable control of metabolic pathway fluxes in E. coli, B. Cress, J. Jones, K. Daniel, Q. Leitz, J. Englaender, S. Collins, R. J. Linhardt, M. Koffas, Nucleic Acids Research, 44, 4472–4485, 2016.
Abstract
Robust gene circuit construction requires use of promoters exhibiting low crosstalk. Orthogonal promoters have been engineered utilizing an assortment of natural and synthetic transcription factors, but design of large orthogonal promoter-repressor sets is complicated, labor-intensive, and often results in unanticipated crosstalk. The specificity and ease of targeting the RNA-guided DNA-binding protein dCas9 to any 20 bp user-defined DNA sequence makes it a promising candidate for orthogonal promoter regulation. Here, we rapidly construct orthogonal variants of the classic T7-lac promoter using site-directed mutagenesis, generating a panel of inducible hybrid promoters regulated by both LacI and dCas9. Remarkably, orthogonality is mediated by only two to three nucleotide mismatches in a narrow window of the RNA:DNA hybrid, neighboring the protospacer adjacent motif. We demonstrate that, contrary to many reports, one PAM-proximal mismatch is insufficient to abolish dCas9-mediated repression, and we show for the first time that mismatch tolerance is a function of target copy number. Finally, these promoters were incorporated into the branched violacein biosynthetic pathway as dCas9-dependent switches capable of throttling and selectively redirecting carbon flux in Escherichia coli. We anticipate this strategy is relevant for any promoter and will be adopted for many applications at the interface of synthetic biology and metabolic engineering.
Description
Nucleic Acids Research, 44, 4472–4485
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Department
The Linhardt Research Labs.
The Shirley Ann Jackson, Ph.D. Center for Biotechnology and Interdisciplinary Studies (CBIS)
Publisher
Oxford University Press
Relationships
The Linhardt Research Labs Online Collection
Rensselaer Polytechnic Institute, Troy, NY
https://harc.rpi.edu/
Access
Open Access
CC BY — Creative Commons Attribution