Biological Circuit Based On Nucleic Acid Conformation Regulation

The transmission of genetic information in organisms follows the genetic central dogma,DNA is transcribed into RNA and then translated into protein,which supports the entire life activities of the organism.At the same time,the abnormal transmission of genetic information can also cause a variety of diseases.The transmission of genetic information in organisms is regulated by the interaction of various biomolecules.For example,the genomic nucleic acid sequence that carries genetic information can be condensed into chromatin through proteins,and the chromatin produces topological remodeling under the regulation of related proteins,thereby regulating the transcriptional activity of the corresponding gene;some non-coding RNAs,such as miRNA,can inhibit the translation activity of mRNA at the post-transcriptional level in the form of RNA-induced silencing complex(RISC).Based on the understanding of the regulation mechanism of natural genetic information,the development of artificial biological circuits constructed by engineered assembly of biomolecules has been in full swing in recent years,and has been widely used in biological manufacturing,computing and treatment.However,the existing artificial biological circuit system lacks a universal module with precise and controllable functions.As the carrier of genetic information,DNA is also the basis of nucleic acid nanostructures.Strict base complementary pairing principle makes DNA nanostructures have precise programmable ability and responsive conformational conversion ability.Therefore,the functionality and structure of DNA can be combined together,and the self-assembled structure of nucleic acid that can precisely control the conformation can be used to develop a universal module to achieve precise control of artificial biological circuits.This article will mainly introduce two general modules constructed using DNA nanostructures: gene transcription switches based on DNA conformation regulation;and micro RNA capture and tumor suppression based on DNA conformation regulation.The specific content is as follows:(1)The linear DNA containing the T7 promoter sequence and the Spinach coding sequence is self-assembled into TO-DNA with other inhibitory strands,and its transcription activity is specifically regulated by the input strand sequence.The transcriptional activity of TO-DNA is highly dependent on the topological structure of the T7 promoter(complete and flat double-stranded structure).Therefore,the topological structure of the T7 promoter on TO-DNA is adjusted by inputting Key to achieve sequence-specific regulation Its transcriptional activity.Moreover,based on this system,we have realized Boolean logic gate operation to regulate TO-DNA transcription activity,sequential cascade regulation among multiple TO-DNAs,and multi-gene orthogonal regulation based on the same TO-DNA and the same promoter.Finally,we use TO-DNA to achieve biological calculations in living bacteria In short,the successful construction of TO-DNA provides a possibility for the development of shape-specific gene vectors,and at the same time enriches the working elements of synthetic biology,which is expected to have a wider range of applications in biological manufacturing and smart theranostics.(2)Self-assembly of diblock DNA containing polyA sequence and anti-miRNA sequence with gold nanospheres was used to construct a spherical nucleic acid(polyASNA)with lateral spacers programmed by polyA length.We found that the length of polyA can programmatically regulate the lateral spacing between anti-miRNA strands on the surface of polyA-SNAs.The size of the lateral spacing will affect the steric hindrance when polyA-SNA binds to the target,thereby affecting its capture efficiency.The tunability of the lateral spacing of PolyA-SNA can support its optimization of a conformation that is more conducive to target capture than traditional densely modified SNA,while ensuring high-efficiency cellular uptake comparable to traditional SNA.Then we verified that polyA-SNAs can capture protocarcinoma miRNAs in cells and rescue the expression of anti-cancer genes.Based on this,we achieved the growth inhibition of mouse subcutaneous tumors.In summary,we use the conformational programmability of DNA nanostructures and their information-carrying capabilities to construct precise artificial biological circuit components based on the conformational regulation of nucleic acid nanostructures.A new method is proposed for the conformational design of exogenous functional nucleic acid,and it also provides new working elements for synthetic biology.