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Title: The legumain McPAL1 from Momordica cochinchinensis is a highly stable Asx-specific splicing enzyme
Authors: Liew, Heng Tai
To, Janet
Zhang, Xiaohong
Hemu, Xinya
Chan, Ning-Yu
Serra, Aida
Sze, Siu Kwan
Liu, Chuan-Fa
Tam, James P.
Keywords: Science::Biological sciences
Issue Date: 2021
Source: Liew, H. T., To, J., Zhang, X., Hemu, X., Chan, N., Serra, A., Sze, S. K., Liu, C. & Tam, J. P. (2021). The legumain McPAL1 from Momordica cochinchinensis is a highly stable Asx-specific splicing enzyme. Journal of Biological Chemistry, 297(6), 101325-.
Project: MOE2016-T3-1-003
Journal: Journal of Biological Chemistry
Abstract: Legumains, also known as asparaginyl endopeptidases (AEPs), cleave peptide bonds after Asn/Asp (Asx) residues. In plants, certain legumains also have ligase activity that catalyzes biosynthesis of Asx-containing cyclic peptides. An example is the biosynthesis of MCoTI-I/II, a squash family-derived cyclic trypsin inhibitor, which involves splicing to remove the N-terminal prodomain and then N-to-C-terminal cyclization of the mature domain. To identify plant legumains responsible for the maturation of these cyclic peptides, we have isolated and characterized a legumain involved in splicing, McPAL1, from Momordica cochinchinensis (Cucurbitaceae) seeds. Functional studies show that recombinantly expressed McPAL1 displays a pH-dependent, trimodal enzymatic profile. At pH 4 to 6, McPAL1 selectively catalyzed Asp-ligation and Asn-cleavage, but at pH 6.5 to 8, Asn-ligation predominated. With peptide substrates containing N-terminal Asn and C-terminal Asp, such as is found in precursors of MCoTI-I/II, McPAL1 mediates proteolysis at the Asn site and then ligation at the Asp site at pH 5 to 6. Also, McPAL1 is an unusually stable legumain that is tolerant of heat and high pH. Together, our results support that McPAL1 is a splicing legumain at acidic pH that can mediate biosynthesis of MCoTI-I/II. We purport that the high thermal and pH stability of McPAL1 could have applications for protein engineering.
ISSN: 0021-9258
DOI: 10.1016/j.jbc.2021.101325
Schools: School of Biological Sciences 
Rights: © 2021 The Authors. Published by Elsevier Inc on behalf of American Society for Biochemistry and Molecular Biology. This is an open access article under the CC BY license (
Fulltext Permission: open
Fulltext Availability: With Fulltext
Appears in Collections:SBS Journal Articles

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