Methods of isolating rna-binding proteins and compositions related to the same

A kit for identifying a nucleic acid that encodes an RNA-binding protein that binds to a specific RNA regulatory element comprising:

• (a) a T7 phase display vector encoding T7 capsid protein 10B;
• (b) an E. coli cell having the genotype F−rna ompT gal hsdSB (rB-mB-) dcm lac pAR5615 (ampR);
• and
• (c) streptavidin-coated paramagnetic beads.

A method of identifying a nucleic acid that encodes an RNA-binding protein that binds to a specific RNA regulatory element comprising:

• (a) inserting a nucleic acid encoding a heterologous protein into a T7 phase display vector, wherein the heterologous protein is expressed as a fusion protein with a phage capsid protein;
• (b) transfecting the T7 phase display vector into a host cell, wherein the host cell has been modified to delete a preselected ribonuclease;
• (c) packaging the phase display vector in a phage capsid in a host cell under conditions which results in lysis of the host cell and formation of a lysate;
• (d) contacting the lysate with a ribonucleotide comprising a specific RNA regulatory element;
• wherein when a phage capsid comprises a nucleic acid that encodes a heterologous protein that binds the specific RNA regulatory element, the phage capsid binds to the ribonucleotide forming an RNA-capsid complex;
• (e) separating the ribonucleotide and the RNA-capsid complex from the lysate;
• and
• (f) identifying the nucleic acid encoding the heterologous protein of the phage capsid of the RNA-capsid complex;
• wherein the nucleic acid identified encodes an RNA-binding protein that binds to the specific RNA regulatory element.