6orm

Publication Abstract from PubMed

Peruvianin-I is a cysteine peptidase (EC 3.4.22) purified from Thevetia peruviana. Previous studies have shown that it is the only germin-like protein (GLP) with proteolytic activity described so far. In this work, the X-ray crystal structure of peruvianin-I was determined to a resolution of 2.15 A (PDB accession number: 6ORM) and its specific location was evaluated by different assays. Its overall structure shows an arrangement composed of a homohexamer (a trimer of dimers) where each monomer exhibits a typical beta-barrel fold and two glycosylation sites (Asn55 and Asn144). Analysis of its active site confirmed the absence of essential amino acids for typical oxalate oxidase activity of GLPs. Details of the active site and molecular docking results, using a specific cysteine peptidase inhibitor (iodoacetamide), were used to discuss a plausible mechanism for proteolytic activity of peruvianin-I. Histological analyses showed that T. peruviana has articulated anastomosing laticifers, i.e., rows of cells which merge to form continuous tubes throughout its green organs. Moreover, peruvianin-I was detected exclusively in the latex. Because latex peptidases have been described as defensive molecules against insects, we hypothesize that peruvianin-I contributes to protect T. peruviana plants against herbivory.

Crystal structure and specific location of a germin-like protein with proteolytic activity from Thevetia peruviana.,Cruz WT, Bezerra EHS, Ramos MV, Rocha BAM, Medina MC, Demarco D, Carvalho CPS, Oliveira JS, Sousa JS, Souza PFN, Freire VN, da Silva FMS, Freitas CDT Plant Sci. 2020 Sep;298:110590. doi: 10.1016/j.plantsci.2020.110590. Epub 2020, Jul 2. PMID:32771148^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.