UASp sequences regulate expression of a nuclease-dead form of Spyo\Cas9 fused to amino acids 1696-2329 of nej, in which the catalytic function of the nej histone acetyltransferase (HAT) domain has been abolished by introducing a F2161A amino acid substitution. The coding sequence is tagged with a nuclear localization signal. This protein fails to act as an artificial transcriptional activator when expressed in cell culture.