T7 promoter T3

The T7 promoter T3 is an engineered promoter that is specifically bound by the engineered T7 (T3) RNA polymerase. The DNA sequence to which T7 RNAP binds is determined by a beta-hairpin, known as the specificity loop, which contacts the -12 to -7 bp region of the promoter (Cheetham et al. 1999). Changes to the specificity loop confer the ability to recognize different promoter sequences (Chelliserrykattil et al. 2001, Esvelt et al. 2011). The binding region in the T7 promoter T3 was mutated from CGACTC to ACCCTC.