Genes encoding 4‐Cys antimicrobial peptides in wheat Triticum kiharae Dorof. et Migush.: multimodular structural organization, instraspecific variability, distribution and role in defence

Abstract

A novel family of antifungal peptides was discovered in the wheat Triticum kiharae Dorof. et Migusch. Two members of the family, designated Tk-AMP-X1 and Tk-AMP-X2, were completely sequenced and shown to belong to the a-hairpinin structural family of plant peptides with a characteristic C1XXXC2-X(n)-C3XXXC4 motif. The peptides inhibit the spore germination of several fungal pathogens in vitro. cDNA and gene cloning disclosed unique structure of genes encoding Tk-AMP-X peptides. They code for precursor proteins of unusual multimodular structure, consisting of a signal peptide, several a-hairpinin (4-Cys) peptide domains with a characteristic cysteine pattern separated by linkers and a C-terminal prodomain. Three types of precursor proteins, with five, six or seven 4-Cys peptide modules, were found in wheat. Among the predicted family members, several peptides previously isolated from T. kiharae seeds were identified. Genes encoding Tk-AMP-X precursors have no introns in the proteincoding regions and are upregulated by fungal pathogens and abiotic stress, providing conclusive evidence for their role in stress response. A combined PCR-based and bioinformatics approach was used to search for related genes in the plant kingdom. Homologous genes differing in the number of peptide modules were discovered in phylogenetically-related Triticum and Aegilops species, including polyploid wheat genome donors. Association of the Tk-AMP-X genes with A, B/G or D genomes of hexaploid wheat was demonstrated. Furthermore, Tk-AMP-X-related sequences were shown to be widespread in the Poaceae family among economically important crops, such as barley, rice and maize.

Prediction of Leymus arenarius (L.) antimicrobial peptides based on de novo transcriptome assembly

“…The alfa-hairpin family includes peptides with diverse functions, such as antifungal activity (Nolde et al 2011;Slavokhotova et al 2014;Utkina et al 2013), inhibition of protein synthesis (Li et al 2003), or protease inhibition (Conners et al 2007;Oparin et al 2012). Although being variable in amino acid sequences, alfa-hairpinins share the same 4-cysteine motif CX(3)CX(1-15)CX(3)C. In lymegrass transcriptome we found 16 putative alfa-hairpinins with this specific motif.…”

The Plant Peptidome: An Expanding Repertoire of Structural Features and Biological Functions

“…Recently, a novel class of ;4-kD Cys-rich peptides, referred to as a-HAIRPININS, has been identified in seeds of several monocots and dicots (Oparin et al, 2012;Utkina et al, 2013;Slavokhotova et al, 2014). a-HAIRPININS are defined by four cysteines and two a-helices (Figure 3).…”

“…a-HAIRPININS are defined by four cysteines and two a-helices (Figure 3). They are derived from a preproprotein containing 5 to 12 a-HAIRPININS (Utkina et al, 2013;Slavokhotova et al, 2014). Various peptides display broad antimicrobial and/or trypsin-inhibitory activity (Oparin et al, 2012;Utkina et al, 2013;de Souza Cândido et al, 2014;Slavokhotova et al, 2014).…”

Structural Similarity between Defense Peptide from Wheat and Scorpion Neurotoxin Permits Rational Functional Design

“…Its measured monoisotopic molecular mass (3548.3 Da) matched the calculated value (3548.6 Da). Correct disulfide linkages were assigned by chemical cleavage: recombinant Tk-AMP-X2 was analyzed as reported previously for the native peptide (17), and Tk-hefu was successively digested by endoproteinase Glu-C and CNBr. The masses of the resulting products unequivocally corresponded to fragments connected by the C 1 -C 4 and C 2 -C 3 bridges.…”

“…In this study, we explore a small ␣-hairpin peptide Tk-AMP-X2 (28 residues) from wheat (Triticum kiharae) seeds (17). This peptide belongs to the ␣-hairpinin family of plant defense peptides (18), which includes both antimicrobial peptides (AMPs) and protease inhibitors (18 -20).…”