3r52

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.