Quantitatively Relating Gene Expression to Light Intensity via the Serial Connection of Blue Light Sensor and CRISPRi

The ability to regulate endogenous
gene expression is critical
in biological research. Existing technologies, such as RNA interference,
zinc-finger regulators, transcription-activator-like effectors, and
CRISPR-mediated regulation, though proved to be competent in significantly
altering expression levels, do not provide a quantitative adjustment
of regulation effect. As a solution to this problem, we place CRISPR-mediated
interference under the control of blue light: while dCas9 protein
is constitutively expressed, guide RNA transcription is regulated
by YF1-FixJ-PFixK2, a blue light responding system. With
a computer-controlled luminous device, the quantitative relationship
between target gene expression and light intensity has been determined.
As the light intensifies, the expression level of target gene gradually
ascends. This remarkable property enables sensor-CRISPRi to accurately
interrogate cellular activities.