posted on 2022-01-19, 17:03authored byWenjiao Fan, Pihua Han, Qinya Feng, Yuanyuan Sun, Wei Ren, Thomas Lawson, Chenghui Liu
As generally acknowledged, terminal
deoxynucleotidyl transferase
(TdT) can only elongate DNA substrates from their 3′-OH ends.
Herein, for the first time, we report that TdT-catalyzed DNA polymerization
can directly proceed on the exosome membrane without the mediation
of any nucleic acids. We prove that both the glycosyl and phenolic
hydroxyl groups on the membrane proteins can initiate the DNA polymerization.
Accordingly, we have developed powerful strategies for high-sensitive
exosome profiling based on a conventional flow cytometer and an emerging
CRISPR/Cas system. By using our strategy, the featured membrane protein
distributions of different cancer cell-derived exosomes can be figured
out, which can clearly distinguish plasma samples of breast cancer
patients from those of healthy people. This work paves new ways for
exosome profiling and liquid biopsy and expands the understanding
of TdT, holding great significance in developing TdT-based sensing
systems as well as establishing protein/nucleic acid hybrid biomaterials.