Publication Abstract from PubMed
Many proteins are induced in the plant defense response to biotic stress or mechanical wounding. One group is lectins. Ipomoelin (IPO) is one of the wound-inducible proteins of sweet potato (Ipomoea batatas cv. Tainung 57) and is a Jacalin-related lectin (JRL). In this study, we resolved the crystal structures of IPO in its apo form and in complex with carbohydrates such as methyl alpha-D-mannopyranoside (Me-Man), methyl alpha-D-glucopyranoside (Me-Glc), and methyl alpha-D-galactopyranoside (Me-Gal) in different space groups. The packing diagrams indicated that IPO might represent a compact tetrameric association in the JRL family. The protomer of IPO showed a canonical beta-prism fold with 12 strands of beta-sheets but with 2 additional short beta-strands at the N terminus. A truncated IPO (DeltaN10IPO) by removing the 2 short beta-strands of the N terminus was used to reveal its role in a tetrameric association. Gel filtration chromatography confirmed IPO as a tetrameric form in solution. Isothermal titration calorimetry determined the binding constants (K(A)) of IPO and DeltaN10IPO against various carbohydrates. IPO could bind to Me-Man, Me-Glc, and Me-Gal with similar binding constants. In contrast, DeltaN10IPO showed high binding ability to Me-Man and Me-Glc but could not bind to Me-Gal. Our structural and functional analysis of IPO revealed that its compact tetrameric association and carbohydrate binding polyspecificity could be regulated by the 2 additional N-terminal beta-strands. The versatile carbohydrate binding properties of IPO might play a role in plant defense.
Ipomoelin, a jacalin-related lectin with a compact tetrameric association and versatile carbohydrate binding properties regulated by its N terminus.,Chang WC, Liu KL, Hsu FC, Jeng ST, Cheng YS PLoS One. 2012;7(7):e40618. Epub 2012 Jul 11. PMID:22808208[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
