Evolution of site-specific recombinases
Some aspects of the present disclosure provide methods for evolving recombinases to recognize target sequences that differ from the canonical recognition sequences. Some aspects of this disclosure provide evolved recombinases, e.g., recombinases that bind and recombine naturally-occurring target sequences, such as, e.g., target sequences within the human Rosa26 locus. Methods for using such recombinases for genetically engineering nucleic acid molecules in vitro and in vivo are also provided. Some aspects of this disclosure also provide libraries and screening methods for assessing the target site preferences of recombinases, as well as methods for selecting recombinases that bind and recombine a non-canonical target sequence with high specificity.
1. An evolved recombinase comprising an amino acid sequence that is at least 95% identical to a protein of SEQ ID NO: 1, wherein the amino acid sequence of the evolved recombinase comprises at least one mutation selected from the group consisting of M44V, A53E, G198S, R241G, A249V, R259C, E262A, I306L, and I320M.
2. The evolved recombinase of claim 1 , wherein the evolved recombinase further comprises at least one of the following mutations: F142L, E69A, A112V, V182I, A231T, or N317T.
3. The evolved recombinase of claim 2 , wherein the evolved recombinase comprises amino acid mutations M44V, A53E, F142L, G198S, R241G, A249V, R259C, E262A, I306L, and I320M.
4. The evolved recombinase of claim 2 , wherein the evolved recombinase comprises amino acid mutations M44V, A53E, E69A, A112V, V182I, G198S, A231T, R241Q, A249V, R259C, E262A, I306L, N317T, and I320M.
5. The evolved recombinase of claim 1 , wherein the evolved recombinase recognizes a DNA recombinase target sequence as set forth in SEQ ID NO: 2.
6. The evolved recombinase of claim 1 , wherein the evolved recombinase does not recognize a DNA recombinase target sequence as set forth in SEQ ID NO: 2.
7. A host cell comprising the evolved recombinase of claim 1 .
8. The host cell of claim 7 , wherein the cell is a human cell.
9. The host cell of claim 7 further comprising a plasmid comprising the sequence set forth in SEQ ID NO: 4.
10. The host cell of claim 9 , wherein the plasmid further comprises a transgene.
11. A method of inserting a transgene into a host cell genome, the method comprising introducing into a host cell having a genome comprising a Rosa26 locus:
(i) the evolved recombinase of claim 1 ; and
(ii) a plasmid comprising a nucleic acid comprising SEQ ID NO:3 and a transgene, under conditions sufficient for the recombinase to insert the transgene into the Rosa26 locus of the host genome.
12. The method of claim 11 , wherein the host cell is a human cell.
13. The method of claim 11 , wherein the transgene is ubiquitously expressed in the host cell after insertion into the Rosa26 locus.
14. An isolated nucleic acid encoding the evolved recombinase of claim 1 .
15. A vector comprising the isolated nucleic acid of claim 14 .
16. The evolved recombinase of claim 1 , wherein the evolved recombinase recognizes a DNA recombinase target sequence that comprises the sequence set forth in SEQ ID NO: 4.