Showing papers by "Karin Thevissen published in 2001"
TL;DR: A series of endosperm transfer layer-specific transcripts has been identified in maize by differential screening of a cDNA library of transcripts at 10 days after pollination, revealing a novel, small gene family of highly diverged sequences encoding basal layer antifungal proteins (BAPs).
Abstract: A series of endosperm transfer layer-specific transcripts has been identified in maize by differential screening of a cDNA library of transcripts at 10 days after pollination Sequence comparisons revealed among this class of cDNAs a novel, small gene family of highly diverged sequences encoding basal layer antifungal proteins (BAPs) The bap genes mapped to two loci on chromosomes 4 and 10 So far, bap-homologous sequences have been detected only in maize, teosinte and sorghum, and are not present in grasses outside the Andropogoneae tribe BAP2 is synthesized as a pre-proprotein, and is processed by successive removal of a signal peptide and a 29-residue prodomain The proprotein can be detected exclusively in microsomal membrane-containing fractions of kernel extracts Immunolocalization reveals BAP2 to be predominantly located in the placentochalazal cells of the pedicel, adjacent to the basal endosperm transfer layer (BETL) cells, although the BAP2 transcript is found only in the BETL cells The biological roles of BAP2 propeptide and mature peptide have been investigated by heterologous expression of the proprotein in Escherichia coli, and by tests of its fungistatic activity and that of the fully processed form in vitro The mature BAP2 peptide exhibits potent broad-range activity against a range of filamentous fungi, including several plant pathogens
99 citations
TL;DR: This study synthesized linear 19-mer peptides, spanning the entire beta2-beta3 loop, that were found to be almost as potent as Rs-AFP2 and cause increased Ca2+ influx in pregerminated fungal hyphae.
Abstract: Rs-AFPs are antifungal proteins, isolated from radish (Raphanus sativus) seed or leaves, which consist of 50 or 51 amino acids and belong to the plant defensin family of proteins. Four highly homologous Rs-AFPs have been isolated (Rs-AFP1-4). The structure of Rs-AFP1 consists of three beta-strands and an alpha-helix, and is stabilized by four cystine bridges. Small peptides deduced from the native sequence, still having biological activity, are not only important tools to study structure-function relationships, but may also constitute a commercially interesting target. In an earlier study, we showed that the antifungal activity of Rs-AFP2 is concentrated mainly in the beta2-beta3 loop. In this study, we synthesized linear 19-mer peptides, spanning the entire beta2-beta3 loop, that were found to be almost as potent as Rs-AFP2. Cysteines, highly conserved in the native protein, are essential for maintaining the secondary structure of the protein. Surprisingly, in the 19-mer loop peptides, cysteines can be replaced by alpha-aminobutyric acid, which even improves the antifungal potency of the peptides. Analogous cyclic 19-mer peptides, forced to adopt a hairpin structure by the introduction of one or two non-native disulfide bridges, were also found to possess high antifungal activity. The synthetic 19-mer peptides, like Rs-AFP2 itself, cause increased Ca2+ influx in pregerminated fungal hyphae.
64 citations