soybean seed protein with carboxylate-binding activity

• Published in: Journal of experimental botany 2005-09, Vol.56 (419), p.2335-2344
• Main Authors: Dhaubhadel, Sangeeta, Kuflu, Kuflom, Romero, Maria Carmen, Gijzen, Mark
• Format: Article
• Language: English
• Subjects: aleurone layer; Amino Acid Sequence; amino acid sequences; Base Sequence; binding capacity; binding proteins; Biological and medical sciences; carboxylic acids; Carboxylic Acids - metabolism; Carrier Proteins - genetics; Carrier Proteins - metabolism; Citrate binding protein; Citrates; Cloning, Molecular; Complementary DNA; Conserved Sequence; DNA Primers; DNA, Complementary; Fundamental and applied biological sciences. Psychology; Gels; gene expression; Genomics; Germination and dormancy; Glycine max; Glycine max - metabolism; immunochemistry; mechanical damage; messenger RNA; Molecular Sequence Data; nucleotide sequences; parenchyma; Pathogens; peroxidase; plant diseases and disorders; Plant physiology and development; plant proteins; Plant Proteins - genetics; Plant Proteins - metabolism; Plants; Proteins; Recombinant Proteins - metabolism; Research Paper; Reverse Transcriptase Polymerase Chain Reaction; seed coat; Seeds; Seeds - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; signal peptide; soybean; Soybeans; Testa; Transcription, Genetic; wound stress
• ISSN: 0022-0957; 1460-2431
• DOI: 10.1093/jxb/eri226

The seed coat serves as a multifunctional organ with a role in protection and for the supply of nutrients to the embryo sac during development. The composition of the legume seed coat differs from other seed tissues in many ways including its protein composition. An abundant 24 kDa protein (SC24) has been purified and identified from soybean (Glycine max [L.] Merr) seed hulls. The corresponding cDNA and genomic DNA clones for SC24 were isolated and characterized, and expression patterns were determined. The deduced protein sequence of 219 amino acids included an N-terminal signal peptide. Transcripts encoding SC24 were present in the seed coat from 30 days after pollination (DAP) until maturity, but the protein was not detected until the final stages of seed maturation. In mature seeds, most of the SC24 protein was localized to the parenchyma and aleurone layers of the seed coat. The expression of SC24 was also induced in vegetative tissues by pathogen infection and by wounding. The SC24 protein bound to an affinity column containing an isophthalic acid ligand, and was eluted with 7 mM citrate. Polyclonal antibodies raised against recombinant SC24 cross-reacted with the seed coat peroxidase enzyme, suggesting that these two proteins may share an antigenic determinant. Overall, the results indicate that SC24 belongs to a novel class of plant defence proteins with carboxylate-binding activity.