Boronic Acid-Linked Apo-Zinc Finger Protein for Ubiquitin Delivery in Live Cells

Delivering cargo into live cells has extensive applications in chemistry, biology, and medicine. Cell-penetrating peptides (CPPs) provide an ideal solution for cellular delivery. Enhancing CPPs with additional functional units can improve delivery efficiency. We investigate the conjugation of boronic acid modules to enhance internalization through interactions with cell surface glycans. The aim of this study is to determine whether adding boronic acid can transform a peptide that typically lacks CPP properties into one that functions as a CPP, enabling the delivery of crucial biological cargo like ubiquitin (Ub). The zinc finger protein in its apo state was selected as a "boronate-enabled" CPP. Results indicate that skeletal point mutations and post-synthetic modifications, combined with conjugated benzoboroxole derivatives, enable the apo-ZFP the ability to transport Ub within A549 cells, confirmed through microscopy and flow cytometry. This effective internalization of cargo offers valuable insights for advancing the development of boronic acid-mediated cell-penetrating peptides.