The invention discloses a side unit used for building TALE (transcription activator-like
effector) repeated sequences. The side unit is a repeated unit
DNA (deoxyribonucleic acid) segment containing isocaudarner or different flat terminase identification sites at two ends, and the preated unit
DNA segment codes repeated units of RVD (repeated variable di-residue) containing NI, NG, HD, NK or NN or variants of the repeated units, wherein in the 5'end isocaudarner or flat terminase identification sites, the 3' end of the identification sites at least has one
nucleotide participating in the
amino acid coding the N end of the side unit; and in the 3' end isocaudarner or flat terminase identification sites, the 5' end of the identification sites at least has one
nucleotide participating in the
amino acid coding the C end of the side unit. The side unit has the advantages that the TALE repeated sequences containing any repeated unit number and any
ranging sequences,
plasmid vectors containing TALE repeated sequences, coding TALE
protein DNA combined structural domains and various derived
fusion protein plasmid vectors can be conveniently built.