T7 phage peptide display system and uses thereof
A bacteriophage T7 display vector for expressing and displaying an exogenous peptide, wherein the display vector comprises a polynucleotide encoding a bacteriophage T7 tail fiber protein p17 in which a hepatocyte-targeting determinant sequence is inactivated, and wherein a cloning site is contained in a coding sequence for the tail fiber protein p17 or in a coding sequence for a capsid protein p10B. Also provided are a host cell containing the display vector as described above, a bacteriophage T7 particle comprising at least one copy of a p17 protein which comprises an exogenous peptide displayed thereon, or at least one copy of a p10 protein with an exogenous peptide displayed thereon, wherein a hepatocyte-targeting determinant sequence on the bacteriophage T7 tail fiber protein p17 is inactivated. The present invention further provides a viral lysate containing assembled bacteriophage T7 particle described above, and a method for determining if a candidate peptide is a liver-targeting peptide, or for screening for liver targeting peptides.
1. A bacteriophage T7 display vector for expressing and displaying a first exogenous peptide encoded by a first exogenous polynucleotide, wherein the bacteriophage T7 display vector comprises a first coding sequence which encodes a bacteriophage T7 tail fiber protein p17, and wherein the first coding sequence comprises the nucleotide sequence of SEQ ID NO: 12 or SEQ ID NO: 13 and contains a first cloning site for insertion of the first exogenous polynucleotide sequence.
2. The bacteriophage T7 display vector according to claim 1 , which further comprises a second coding sequence which encodes a T7 capsid protein p10B and contains a second cloning site for insertion of a second exogenous polynucleotide encoding a second exogenous peptide, wherein the T7 capsid protein p10B comprises the amino acid sequence of SEQ ID NO: 10 or SEQ ID NO: 11.
3. The bacteriophage T7 display vector of claim 1 , which further comprises a second coding sequence which encodes a truncated T7 capsid protein p10B and contains a second cloning site for insertion of a second exogenous polynucleotide encoding a second exogenous peptide, wherein the truncated T7 capsid protein p10B comprises the amino acid sequence of positions 1-27 of SEQ ID NO: 10, or the amino acid sequence of SEQ ID NO: 11.
4. The bacteriophage T7 display vector of claim 3 , wherein the first or second exogenous peptide comprises at least 7 amino acid residues.
5. The bacteriophage T7 display vector of claim 4 , wherein the first or second exogenous peptide comprises not more than 19 amino acid residues.
6. The bacteriophage T7 display vector of claim 3 , further comprising wild-type T7 protein p17 regulatory signals.
7. The bacteriophage T7 display vector of claim 6 , wherein the wild-type capsid T7 protein p17 regulatory signals comprise a promoter, or a translation initiation signal, or both.
8. The bacteriophage T7 display vector of claim 7 , further comprising a wild type p17 terminator.
9. The bacteriophage T7 display vector according to claim 3 , wherein the second cloning site is contained in the coding sequence for the truncated T7 capsid protein p10B and the exogenous nucleotide sequence is inserted at the C terminus of the truncated T7 capsid protein p10B, or in frame internally of the truncated T7 capsid protein p10B.
10. A cell containing a bacteriophage T7 display vector of claim 1 .