The invention belongs to the field of
gene engineering. Specifically, the invention relates to a base editing
system for optimizing engineered T cells and application of the base editing
system. The present invention provides a base editing
system for modifying engineered T cells, comprising: i) a base editing polypeptide, and / or an expression construct encoding a base editing polypeptide, the base editing polypeptide comprising
a DNA binding protein and at least one deaminase domain; ii) a
guide RNA, and / or an expression construct encoding a
guide RNA, the
guide RNA targeting any one of TRAC, TGFBR2, PD-1, CISH, and / or FAS genomic regions, or any combination thereof. The base editing system disclosed by the invention has high efficiency of a
gene editing tool and low
Indel frequency, can realize accurate editing of
T cell function enhancement related genes, and has important value for expanding application scenes of a base editing technology in the fields of preparation of safe and efficient engineered T cells and the like.