Split single-base gene editing systems and application thereof

A nucleic acid construct combination comprising a first nucleic acid construct and a second nucleic acid construct, wherein the first nucleic acid construct has a structure of Formula I from 5′-3′:

• P1-X1-X2-X3-Z-X4 (I);
• wherein P1 is a first promoter sequence;
• X1 is a coding sequence of cytosine deaminase or a coding sequence of adenosine deaminase;
• X2 is an optional linker sequence;
• X3 is a coding sequence of the N-terminal fragment of Cas9 nuclease or a coding sequence of the N-terminal fragment of SaKKH nuclease (Cas9n-N or SSaKKH-N);
• Z is a coding sequence of the N-terminal fragment of a first fusion peptide;
• X4 is a polyA sequence;
• the second nucleic acid construct has a structure of Formula II from 5′-3′:
• P2-Z-Y1-Y2-Y3 (II);
• wherein P2 is a second promoter sequence;
• Z is a coding sequence of the C-terminal fragment of a first fusion peptide;
• Y1 is a coding sequence of the C-terminal fragment of Cas9 nuclease or a coding sequence of the C-terminal fragment of SSaKKH nuclease (Cas9n-C or SSaKKH-C);
• Y2 is a coding sequence of UGI or none;
• Y3 is a polyA sequence;
• and each “-” is independently a bond or a nucleotide linker sequence.