Exploring Phage Peptide Scaffolds: Tyrosinase-Mediated Cyclization for Selective Generation of Bioactive Cyclic Peptides

Phage
display is an ideal platform for selecting peptide
hits and
offers a diverse array of cyclic binders with high affinity. While
many recently developed phage display platforms incorporate chemical
strategies, the vast majority of these are detrimental to the phage
life cycle due to cross-reactivity with the capsid protein. In contrast,
enzyme catalysis, which combines high efficiency and biocompatibility,
offers a promising approach for phage-based cyclic peptide display.
However, enzyme-mediated cyclization approaches remain underexplored.
Here, we present a tyrosinase-mediated phage display platform that
enables one-step cyclization via o-quinone-cysteine
coupling, which is a simple and efficient strategy that does not compromise
phage infectivity. Importantly, the catalytic property of tyrosinase
is highly selective and spatially constrained, allowing it to bypass
native tyrosine residues in the phage and selectively recognize only
the engineered tyrosine residues. Using this platform, we constructed
a macrocyclic peptide library that facilitated the discovery of macrocyclic
peptide inhibitors targeting therapeutically relevant proteins. Notably,
the cyclic peptide ACI1 demonstrated potent inhibition of PIP4K2A
kinase activity with an IC50 value of 0.93 ± 0.05
μM, while ACP1 effectively inhibited the dephosphorylation activity
of PTP1B with an IC50 of 1.06 ± 0.25 μM. The
generality and efficiency of this strategy highlight its potential
as a valuable tool for the development of bioactive cyclic peptides.