Wang XB, Zhang CH, Zhang T, Li HZ, Liu YL, Xu ZG, Lei G, Cai CJ, Guo ZY. An efficient peptide ligase engineered from a bamboo asparaginyl endopeptidase.
FEBS J 2024;
291:2918-2936. [PMID:
38525648 DOI:
10.1111/febs.17111]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 02/07/2024] [Accepted: 02/22/2024] [Indexed: 03/26/2024]
Abstract
In recent years, a few asparaginyl endopeptidases (AEPs) from certain higher plants have been identified as efficient peptide ligases with wide applications in protein labeling and cyclic peptide synthesis. Recently, we developed a NanoLuc Binary Technology (NanoBiT)-based peptide ligase activity assay to identify more AEP-type peptide ligases. Herein, we screened 61 bamboo species from 16 genera using this assay and detected AEP-type peptide ligase activity in the crude extract of all tested bamboo leaves. From a popular bamboo species, Bambusa multiplex, we identified a full-length AEP-type peptide ligase candidate (BmAEP1) via transcriptomic sequencing. After its zymogen was overexpressed in Escherichia coli and self-activated in vitro, BmAEP1 displayed high peptide ligase activity, but with considerable hydrolytic activity. After site-directed mutagenesis of its ligase activity determinants, the mutant zymogen of [G238V]BmAEP1 was normally overexpressed in E. coli, but failed to activate itself. To resolve this problem, we developed a novel protease-assisted activation approach in which trypsin was used to cleave the mutant zymogen and was then conveniently removed via ion-exchange chromatography. After the noncovalently bound cap domain was dissociated from the catalytic core domain under acidic conditions, the recombinant [G238V]BmAEP1 displayed high peptide ligase activity with much lower hydrolytic activity and could efficiently catalyze inter-molecular protein ligation and intramolecular peptide cyclization. Thus, the engineered bamboo-derived peptide ligase represents a novel tool for protein labeling and cyclic peptide synthesis.
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