Light-responsive control of bacterial gene expression: precise triggering of the lacpromoter activity using photocaged IPTG

• Published in: Integrative biology (Cambridge) 2014-07, Vol.6 (8), p.755-765
• Main Authors: Binder, Dennis, Gruenberger, Alexander, Loeschcke, Anita, Probst, Christopher, Bier, Claus, Pietruszka, Jorg, Wiechert, Wolfgang, Kohlheyer, Dietrich, Jaeger, Karl-Erich, Drepper, Thomas
• Format: Article
• Language: English
• Subjects: Escherichia coli
• ISSN: 1757-9694; 1757-9708
• DOI: 10.1039/c4ib00027g

Light can be used to control numerous cellular processes including protein function and interaction as well as gene expression in a non-invasive fashion and with unprecedented spatiotemporal resolution. However, for chemical phototriggers tight, gradual, and homogeneous light response has never been attained in living cells. Here, we report on a light-responsive bacterial T7 RNA polymerase expression system based on a photocaged derivative of the inducer molecule isopropyl- beta -d-thiogalactopyranoside (IPTG). We have comparatively analyzed different Escherichia coli lacpromoter-regulated expression systems in batch and microfluidic single-cell cultivation. The lacY-deficient E. colistrain Tuner(DE3) harboring additional plasmid-born copies of the lacIgene exhibited a sensitive and defined response to increasing IPTG concentrations. Photocaged IPTG served as a synthetic photo-switch to convert the E. colisystem into an optogenetic expression module allowing for precise and gradual light-triggering of gene expression as demonstrated at the single cell level.