The present invention relates to a polynucleotide encoding a fusion polypeptide comprising an anti-CRISPR (Acr) polypeptide, wherein said fusion polypeptide further comprises a receptor domain changing conformation upon reception of a stimulus. The present invention also relates to a vector comprising the polynucleotide of the present invention, to a bipartite Acr polypeptide comprising a first partial Acr polypeptide comprising amino acids corresponding to amino acids 10 to 62 of SEQ ID NO : 1, and a second partial Acr polypeptide comprising amino acids corresponding to amino acids 67 to 77 of SEQ ID NO : 1, and to a host cell comprising the aforesaid polynucleotide compounds. The present invention also relates to the said compounds for use in medicine, in particular for use in treatment and/or prevention of genetic disease, neurodegenerative disease, cancer, and/or infectious disease. Moreover, the present invention also relates to a kit, methods, and uses related thereto.