Gene expression includes two stages: transcription and translation. Transcription refers to the process that a specific sequence of DNA is copied into mRNA by RNA polymerase. Translation refers to the process of generating the corresponding amino acid sequence and synthesizing the polypeptide chain according to the central law of genetic code with mRNA as the template, and the polypeptide chain is finally folded into the functional protein in the cell.

Transcription factors are proteins that can bind to specific nucleotide sequences upstream of a certain gene. These proteins can regulate gene expression by regulating the combination of RNA polymerase and DNA template. In the structure of transcription factors, DNA binding domain (DBD) is responsible for identifying and binding DNA sequences upstream of specific genes; Activation domain (AD) is responsible for interacting with other proteins, activating RNA polymerase and initiating transcription.

A Novel Tool for Endogenous Gene Expression Regulation

For a long time, researchers mainly use some chemical molecules to regulate gene expression, but the toxicity, nonspecificity and difficulty in realizing spatio-temporal regulation of chemical molecules limit their application. Light has the characteristics of low toxicity, easy manipulation and high temporal and spatial resolution. Therefore, optogenetic tools are widely used to accurately regulate gene expression.

The Principle Light Controlled Gene Expression

The commonly used expression mode of light controlled genes uses light controlled heterodimerization. For convenience of description, heterodimerized proteins are divided into photosensitive protein (A) and photosensitive protein binding protein (B).

In the light controlled gene expression system, photosensitive protein A is fused with DBD, which can bind to DNA molecules by recognizing specific sequences near the promoter on DNA; Binding protein B fused with AD. Under the light of a specific wavelength, photosensitive protein A is excited to change its shape so that it can combine with protein B, so as to recruit the DNA activation domain near the promoter and start the transcription and expression of the target gene. The combination of a and B is reversible. Therefore, when there is no light stimulation, the A-B complex dissociates and the gene expression stops

Achievable Missions at Creative BioMart

Creative BioMart has mastered and developed a variety of optical switching systems for endogenous gene expression regulation. We have the ability to provide the construction services of cell lines, expression systems and model organisms.

Study of gene expression in yeast—red light

PhyB-PIF3, a pair of photosensitive proteins, is one of the commonly used optogenetic switches. By connecting PhyB and PIF3 to the binding domain and activation domain of yeast transcription activating protein Gal4 respectively, the gene expression controlled by red light can be turned on and off.

Study of gene expression in mammalian cells—red light

PhyB-PIF6 switch is also controlled by red light. Different from PhyB-PIF3, this switch can be used to regulate gene expression in mammalian cells. Under the irradiation of red light, the expression of target gene will be activated and expressed.

Study of gene expression in zebrafish—blue light

CRY2-CIB1 photosensitive switch is controlled by blue light. The light controlled expression of target gene can be realized by inserting blue light switch into zebrafish embryo by bioengineering.

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