Recombinant nucleic acid molecule based on point mutation of translation initiation element and use thereof in preparation of circular RNA

A recombinant nucleic acid molecule for preparing a circular RNA, wherein in the 5′ to 3′ direction, the recombinant nucleic acid molecule comprises elements arranged in the following order:

• an intron fragment II, a truncated fragment II of the translational initiation element, a coding element encoding at least one target polypeptide, a truncated fragment I of the translation initiation element, and an intron fragment I, wherein the truncated fragment II of the translational initiation element comprises the nucleotide sequence of SEQ ID NO:
• 14, and the truncated fragment I of the translation initiation element comprises the nucleotide sequence of SEQ ID NO:
• 13;
• wherein the 3′ end of the truncated fragment I of the translation initiation element includes ribozyme recognition site I consisting of a first predetermined number of nucleotides located at the 3′ end of the truncated fragment I of the translation initiation element;
• the 5′ end of the truncated fragment II of the translational initiation element includes a ribozyme recognition site II consisting of a second predetermined number of nucleotides located at the 5′ end of the truncated fragment II of the translational initiation element;
• the nucleotide sequence of the truncated fragment I of the translation initiation element and the nucleotide sequence of the truncated fragment II of the translational initiation element are used to form a translation initiation element sequence in the 5′ to 3′ direction;
• the nucleotide sequence of the truncated fragment I of the translation initiation element corresponds to a partial sequence of the translation initiation element sequence near the 5′ direction, and the nucleotide sequence of the truncated fragment II of the translational initiation element corresponds to a remaining partial sequence of translation initiation element sequence near the 3′ direction;
• the nucleotide sequence of the intron fragment I and the nucleotide sequence of the intron fragment II are used to form an intron sequence in the 5′ to 3′ direction;
• the nucleotide sequence of intron fragment I includes a partial sequence of the intron sequence near the 5′ direction, and the nucleotide sequence of intron fragment II includes the remaining partial sequence of the intron sequence near the 3′ direction.