Butelase 1 is an Asx-specific ligase enabling peptide macrocyclization and synthesis

• Published in: Nature chemical biology Vol. 10; no. 9; pp. 732 - 738
• Main Authors: Nguyen, Giang K T, Wang, Shujing, Qiu, Yibo, Hemu, Xinya, Lian, Yilong, Tam, James P
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01-09-2014; Nature Publishing Group
• Subjects: 45/91; 631/449; 631/92/458; 631/92/468; 631/92/611; 82/16; 82/29; 82/58; 82/75; 82/80; 82/81; 82/83; Amino Acid Sequence; Amino acids; Animals; Asparagine; Asparagine - metabolism; Aspartic Acid - metabolism; Aspartic Acid Endopeptidases - metabolism; Biochemical Engineering; Biochemistry; Bioorganic Chemistry; C-Terminus; Cell Biology; Chemical reactions; Chemistry; Chemistry/Food Science; Clitoria - enzymology; Cyclization; Disulfides - metabolism; Enzymes; Herbal medicine; Homology; Humans; Hydrolysis; Kinetics; Legumain; Ligands; Ligases - metabolism; Macrocyclic Compounds - chemical synthesis; Macrocyclic Compounds - metabolism; Medicinal plants; Models, Molecular; Molecular Sequence Data; Peptide Synthases - chemistry; Peptide Synthases - isolation & purification; Peptides; Peptides - chemistry; Peptides - metabolism; Plant Proteins - chemistry; Plant Proteins - isolation & purification; Proteases; Protein synthesis; Recombinant Proteins - chemistry; Substrate Specificity; Substrates
• ISSN: 1552-4450; 1552-4469
• DOI: 10.1038/nchembio.1586

Peptide macrocycles are attracting increasing attention as tools for research and as potential therapeutics. The highly efficient butelase 1—homologous to proteases but specific for ligations—offers a new method for peptide cyclization.
Proteases are ubiquitous in nature, whereas naturally occurring peptide ligases, enzymes catalyzing the reverse reactions of proteases, are rare occurrences. Here we describe the discovery of butelase 1, to our knowledge the first asparagine/aspartate (Asx) peptide ligase to be reported. This highly efficient enzyme was isolated from
Clitoria ternatea
, a cyclic peptide–producing medicinal plant. Butelase 1 shares 71% sequence identity and the same catalytic triad with legumain proteases but does not hydrolyze the protease substrate of legumain. Instead, butelase 1 cyclizes various peptides of plant and animal origin with yields greater than 95%. With
K
cat
values of up to 17 s
−1
and catalytic efficiencies as high as 542,000 M
−1
s
−1
, butelase 1 is the fastest peptide ligase known. Notably, butelase 1 also displays broad specificity for the N-terminal amino acids of the peptide substrate, thus providing a new tool for C terminus–specific intermolecular peptide ligations.