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Crystal structure of alpha-amylase inhibitor wrightide R1 (wR1) peptide from Wrightia religiosa
Structural highlights
FunctionPublication Abstract from PubMedObesity and type-2 diabetes are chronic metabolic diseases that could be benefited by the use of alpha-amylase inhibitors to manage starch intake. The pseudocyclics, wrightides Wr-AI1 to Wr-AI3, isolated from an Apocynaceae plant show promising potentials for further development as orally active alpha-amylase inhibitors. These linear peptides retain the stability known for cystine knot peptides in harsh treatment. They are resistant to treatment by heat, endopeptidase or exopeptidase, characteristics of cyclic cystine knot peptides. Our NMR and crystallography analysis also showed that wrightides, currently the smallest proteinaceous alpha -amylase inhibitors reported, contain the backbone-twisting cis proline which is preceded by a non-aromatic residue rather than a conventional aromatic residue. Modeled structure and molecular dynamics study of Wr-AI1 in complex with yellow meal worm alpha-amylase suggested that despite similar structure and cystine knot fold, members of knottin-type alpha-amylase inhibitors may bind to insect alpha-amylase via a different set of interactions. Finally, we showed that the precursors of pseudocyclic cystine knot alpha-amylase inhibitors and their biosynthesis in plants follow secretory protein synthesis pathway. Together, our work provides insights for the use of the pseudocyclic alpha-amylase inhibitors as useful leads for developing orally active peptidyl bioactives as well as an alternative scaffold to cyclic peptides for engineering metabolic-stable human alpha-amylase inhibitors. This article is protected by copyright. All rights reserved. Discovery and Characterization of Pseudocyclic Cystine-Knot alpha-Amylase Inhibitors with High Resistance to Heat and Proteolytic Degradation.,Nguyen PQ, Wang S, Kumar A, Yap LJ, Luu TT, Lescar J, Tam JP FEBS J. 2014 Jul 21. doi: 10.1111/febs.12939. PMID:25040200[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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