iCONM develops new technology — Drug discovery target screening without cells

A research group including Deputy Principal Research Scientist Shingo Ueno of the Innovation Center of NanoMedicine (iCONM), under the Kawasaki Institute of Industrial Promotion, has announced the development of "PL-Display," a high-precision technology for discovering peptides that serve as drug discovery targets without using living cells. By fixing candidate peptides and their encoding DNA onto magnetic beads, high-precision screening becomes possible. It is expected to be applied in the fields of drug discovery, diagnostics, and biomaterial development. The results were published in PNAS Nexus on February 13.

Techniques for finding proteins or peptides that bind perfectly to specific targets are crucial for drug discovery and clarifying disease mechanisms. Various "display technologies" have been developed to identify these binding proteins. These methods physically link a protein or peptide to its encoding DNA or RNA, allowing researchers to identify the genetic sequence corresponding to a selected protein. A prime example is Phage Display, which was recognized with the Nobel Prize in Chemistry in 2018.

In this study, the team developed a new method to fix cell-free synthesized proteins onto the surface of magnetic microbeads. They utilized the properties of "peptide ligase," an enzyme that links peptides together. A peptide and DNA that codes it, are fixed via a fragment consisting of nine amino acids (codon). One peptide and its DNA are displayed correspondingly on one bead. Fluorescence-activated cell sorting (FACS) is used to find proteins with the desired properties based on numerical values. Cell-free protein synthesis does not require growing cells because proteins are made in a test tube without using living cells, allowing for a free and efficient search for the desired protein.

Cell-free protein synthesis does not require growing cells because proteins are made in a test tube without using living cells, allowing for a free and efficient search for the desired protein. Compared to conventional methods, this new approach is over 10 times more efficient and enables screening even under extreme conditions, such as high temperatures or high salinity.

The team successfully detected a single specific peptide out of 10,000 in a single screening session. They also confirmed the ability to efficiently detect targets from a random peptide library containing approximately 1.7 million types.

Broad applications are expected, including the search for therapeutic and diagnostic peptides or small-molecule antibodies, the development of industrial proteins used in non-physiological environments, and high-speed screening through automation and robotics utilizing the magnetic bead platform.

Ueno said, "We devised quantitative screening using magnetic beads, aiming for a simple, reliable, and secure technology that does not rely on 'craftsmanship' or luck. Based on the PL-Display platform, we are currently expanding into small-molecule antibody discovery and biochemical assay screening. I believe the magnetic bead platform can be extended beyond molecular discovery, so please feel free to reach out if you are interested."

Journal Information
Publication: PNAS Nexus
Title: Peptide ligase-mediated display: A cell-free platform for tunable selection of affinity peptides
DOI: 10.1093/pnasnexus/pgag031