Ipomoelin, a Jacalin-Related Lectin with a Compact Tetrameric Association and Versatile Carbohydrate Binding Properties Regulated by Its N Terminus
Resource
PLOS ONE, 7(7), e40618
Journal
PLOS ONE
Journal Volume
7
Journal Issue
7
Pages
-
Date Issued
2012
Date
2012
Author(s)
Abstract
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 α-D-mannopyranoside (Me-Man), methyl α-D-glucopyranoside (Me-Glc), and methyl α-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 β-prism fold with 12 strands of β-sheets but with 2 additional short β-strands at the N terminus. A truncated IPO (ΔN10IPO) by removing the 2 short β-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 (KA) of IPO and ΔN10IPO against various carbohydrates. IPO could bind to Me-Man, Me-Glc, and Me-Gal with similar binding constants. In contrast, ΔN10IPO 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 β-strands. The versatile carbohydrate binding properties of IPO might play a role in plant defense. © 2012 Chang et al.
Other Subjects
alpha methyl mannoside; alpha methylglucoside; carbohydrate; ipomoelin; methyl alpha dextro galactopyranoside; plant lectin; unclassified drug; amino terminal sequence; article; beta prism; beta sheet; beta strand; binding affinity; complex formation; crystal structure; gel filtration chromatography; isothermal titration calorimetry; nonhuman; nucleotide sequence; plant defense; protein analysis; protein carbohydrate interaction; protein family; protein folding; protein structure; regulatory mechanism; structure activity relation; Amino Acid Sequence; Binding Sites; Carbohydrate Metabolism; Carbohydrate Sequence; Carbohydrates; Chromatography, Gel; Crystallography, X-Ray; Hydrogen Bonding; Kinetics; Methylation; Models, Molecular; Molecular Sequence Data; Mutant Proteins; Plant Lectins; Plant Proteins; Protein Binding; Protein Structure, Quaternary; Sequence Alignment; Structure-Activity Relationship; Ipomoea batatas
Type
journal article
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