Defensins--components of the innate immune system in plants.
Plant defensins are small (c.a. 5 kDa), basic, cysteine-rich proteins with antimicrobial activities. They are ubiquitous in plants and form part of the innate immunity arsenal. Plant defensins are encoded by small multigene families and are expressed in various plant tissues, but are best characterized in seeds. They are typically produced as preproteins, however, a small subset are produced as larger precursors with C-terminal prodomains. To date, the three-dimensional solution structures of seven seed- and two floral-derived defensins have been elucidated by (1)H-NMR spectroscopy. Despite limited amino acid sequence identities, these defensins have comparable global folds with features that are characteristic of the cysteine-stabilized alphabeta (CSalphabeta) motif. Interestingly, their structures are remarkably similar to those of insect defensins and scorpion toxins. Functionally, these proteins exhibit a diverse array of biological activities, although they all serve a common function as defenders of their hosts. This review describes the distribution, biosynthesis, structure, function and mode of action of plant defensins and reflects on their potential in agribiotechnological applications.
Lay
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Department of Biochemistry, La Trobe University, Bundoora, Victoria 3086, Australia.
Anderson
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MA
D000595:Amino Acid Sequence; D000818:Animals; D000935:Antifungal Agents / Q000494:pharmacology; D003545:Cysteine / Q000737:chemistry; D023082:Defensins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D005658:Fungi / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000235:genetics / Q000276:immunology*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D010944:Plants / Q000276:immunology*; D012604:Scorpion Venoms / Q000737:chemistry; D017386:Sequence Homology, Amino Acid
D000935:Antifungal Agents; D023082:Defensins; D010940:Plant Proteins; D012604:Scorpion Venoms; D003545:Cysteine