Position dependent recognition of GNN nucleotide triplets by zinc fingers
The specificity of binding of a zinc finger to a triplet or quadruplet nucleotide target subsite depends upon the location of the zinc finger in a multifinger protein and, hence, upon the location of its target subsite within a larger target sequence. The present disclosure provides zinc finger amino acid sequences for recognition of triplet target subsites having the nucleotide G in the 5′-most position of the subsite, that have been optimized with respect to the location of the subsite within the target site. Accordingly, the disclosure provides finger position-specific amino acid sequences for the recognition of GNN target subsites. This allows the construction of multi-finger zinc finger proteins with improved affinity and specificity for their target sequences, as well as enhanced biological activity.
1. A zinc finger protein that binds to a target site in a gene in a position-specific fashion, the target site comprising, in a 3′ to 5′ direction, first (S1), second (S2) and third (S3) target subsites, each target subsite having the nucleotide sequence GNN, the zinc finger protein comprising:
(a) a non-naturally-occurring zinc finger protein that has been engineered to bind the target site; and
(b) first (F1), second (F2) and third (F3) zinc fingers ordered F1, F2, F3 from N-terminus to C-terminus that bind to S1, S2 and S3, wherein:
if S1 comprises GGA, F1 comprises the amino acid sequence QSGHLAR (SEQ ID NO:413);
if S2 comprises GGT, F2 comprises the amino acid sequence TSGHLSR (SEQ ID NO:1201);
if S2 comprises GCA, F2 comprises QSGDLTR (SEQ ID NO:220);
if S2 comprises GCC, F2 comprises the amino acid sequence DRSDLTR (SEQ ID NO:417);
if S3 comprises GAT, F3 comprises the amino acid sequence TSANLSR (SEQ ID NO:377);
if S3 comprises GCA, F3 comprises QSGDLTR (SEQ ID NO:220);
if S3 comprises GCC, F3 comprises the amino acid sequence DRSDLTR (SEQ ID NO:417);
if S3 comprises GCT, F3 comprises the amino acid sequence QSSDLQR (SEQ ID NO: 132);
and further wherein the zinc finger protein binds to the target site, thereby modulating expression of the gene.
2. The zinc finger protein of claim 1 , further comprising a regulatory domain.