MICROBEADS WITH RATIOMETRIC LANTHANIDE ENCODING FOR DRUG SCREENING
The disclosure provides methods and compositions for identifying agents that modulate binding of a protein to a peptide binding partner using spectrally encoded microbeads comprising binding site peptides in which there is a 1:1 linkage between sequences of the binding site peptide and the embedded spectral code.
1 . A method of identifying an agent that modulates interaction of a protein of interest with a binding site peptide, the method comprising providing a population of microbead-bound peptides comprising microbeads having distinguishable spectral codes, wherein a first microbead having a specific spectral code comprises a peptide having a first sequence that binds to the protein of interest, and a microbead having a different spectral code comprises a peptide having a second sequence that binds to the protein of interest, wherein the second sequence differs from the first sequence;
contacting the population of microbeads with the protein of interest and a candidate agent for modulating binding of the protein interest to peptides present on the microbeads;
detecting binding of the protein of interest to peptides on individual beads; and
determining the spectral signature of individual microbeads, thereby determining the identity of the peptide linked to each bead.
2 . The method of claim 1 , wherein the distinguishable spectral codes are lanthanide spectral codes.
3 . The method of claim 1 , wherein the protein of interest comprises a detectable label.
4 . The method of claim 1 , or wherein the step of detecting binding of the protein of interest comprises contacting the population of microbeads with a detection reagent that binds to the protein of interest, wherein the detection reagent comprises a detectable label.
5 . The method of claim 1 , wherein the contacting step comprises contacting a pooled population of microbeads with the protein of interest.
6 . The method of claim 5 , further comprising distributing the pooled population into an array configuration.
7 . The method of claim 1 , wherein the lanthanide spectral codes are detecting by deep UV imaging.
8 . The method of claim 1 , wherein the detectable label comprises a fluorescent label.
9 . The method of claim 1 , wherein binding of the protein of interest to peptides present on individual microbeads is detected by image analysis.
10 . The method of claim 1 , wherein the peptides are synthesized on the microbeads.
11 . The method of claim 1 , wherein the detecting step comprises quantifying signal generated from the detectable label for protein bound to peptides on individual microbeads.
12 . The method of claim 1 , further comprising selecting an agent that decreases the amount of signal generated.
13 . The method of claim 1 , wherein the agent is a small molecule.
14 . The method of claim 1 , wherein the agent is a peptide, antibody, or aptamer.
15 . The method of claim 1 , wherein the population of microbeads is a portion of a library of microbeads and the method further comprises detecting binding of the protein of interest to multiple populations of microbeads, wherein each population is from the same library and each population is present in an individual compartment, and wherein different candidate agents are added to the individual compartments.
16 . An array comprising populations of lanthanide-encoded microbeads, each from the same library of microbeads, distributed into individual compartments, wherein each population comprises microbeads having distinguishable lanthanide spectral codes, wherein each microbead comprises a peptide comprising a binding site to a protein of interest attached thereto and wherein each microbead having the same spectral code comprises a peptide comprising the same binding site sequence and microbeads having different spectral codes comprise peptides comprising sites that differ in sequence.
17 . An array of claim 16 , wherein each compartment further comprises the protein of interest and a candidate agent that modulates binding.
18 . The array of claim 16 , wherein the candidate agent is a small molecule.