Characterization and cDNA cloning of two glycine- and histidine-rich antimicrobial peptides from the roots of shepherd's purse, Capsella bursa-pastoris

• Published in: Plant molecular biology Vol. 44; no. 2; pp. 187 - 197
• Main Authors: Park, C J, Park, C B, Hong, S S, Lee, H S, Lee, S Y, Kim, S C
• Format: Journal Article
• Language: English
• Published: Netherlands 01.09.2000
• Subjects: Amino Acid Sequence; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Bacteria - drug effects; Bacteria - growth & development; Base Sequence; Blotting, Northern; Blotting, Southern; Brassicaceae - genetics; Capsella bursa-pastoris; Cell Division - drug effects; Circular Dichroism; Cloning, Molecular; DNA, Complementary - chemistry; DNA, Complementary - genetics; DNA, Plant - genetics; Fungi - drug effects; Fungi - growth & development; Gene Expression Regulation, Plant; Glycine - genetics; Histidine - genetics; Microbial Sensitivity Tests; Molecular Sequence Data; Peptides; Plant Proteins - genetics; Plant Proteins - pharmacology; Plant Roots - genetics; Protein Isoforms - genetics; Protein Isoforms - pharmacology; RNA, Plant - genetics; RNA, Plant - metabolism; Sequence Alignment; Sequence Analysis, DNA; Sequence Analysis, Protein; Sequence Homology, Amino Acid; shepherin I; shepherin II; Tissue Distribution
• ISSN: 0167-4412; 1573-5028
• DOI: 10.1023/A:1006431320677

Two novel antimicrobial peptides were isolated and characterized from the roots of shepherd's purse, Capsella bursa-pastoris. These antimicrobial peptides, named shepherin I and shepherin II, consist of 28 and 38 amino acids, respectively, and are glycine- and histidine-rich peptides. Shepherin I and shepherin II have 67.9% and 65.8% (mol/mol) glycine, respectively, and 28.6% and 21.1% (mol/mol) histidine, respectively. Both shepherins have a Gly-Gly-His motif. These antimicrobial peptides exhibit antimicrobial activity against Gram-negative bacteria and fungi. Circular dichroism spectra of shepherin I and shepherin II showed that shepherin I and shepherin II in 50% trifluoroethanol have 66.7% and 75% random coils, respectively, without any alpha-helices. cDNA sequence analysis revealed that shepherin I and shepherin II are produced from a single polypeptide, designated shep-GRP, consisting of 120 amino acids; shep-GRP has five distinct domains, an amino-terminal putative signal peptide, a shepherin I, a linker dipeptide, a shepherin II and a carboxy-terminal peptide. Southern blot analysis indicates that the gene encoding shepherins belongs to a low-complexity gene family. Northern blot analysis revealed that transcripts of shep-GRP are present in roots but not in leaves and stems.