title: Enhanced antifungal and insect α-amylase inhibitory activities of Alpha-TvD1, a peptide variant of Tephrosia villosa defensin (TvD1) generated through in vitro mutagenesis.
abstract: TvD1 is a small, cationic, and highly stable defensin from the weedy legume, Tephrosia villosa with demonstrated in vitro antifungal activity. We show here peptide modifications in TvD1 that lead to enhanced antifungal activities. Three peptide variants, S32R, D37R, and Alpha-TvD1 (-G-M-T-R-T-) with variations in and around the β2-β3 loop region that imposes the two β-strands, β2 and β3 were generated through in vitro mutagenesis. Alpha-TvD1 exhibited enhanced antifungal activity against the fungal pathogens, Fusarium culmorum and Fusarium oxysporum with respective IC(50) values of 2.5 μM and 3.0 μM, when compared to S32R (<5.0 μM and >5.0 μM), D37R (5.5 μM and 4.5 μM), and the wild type TvD1 (6.5 μM). Because of the enhanced antifungal activity, this variant peptide was characterized further. Growth of F. culmorum in the presence of Alpha-TvD1 showed deformities in hyphal walls and nuclear damage. With respect to the plant pathogenic bacterium, Pseudomonas syringae pv. tomato strain DC3000, both Alpha-TvD1 and the wild type TvD1 showed comparable antibacterial activity. Both wild type TvD1 and Alpha-TvD1 displayed inhibitory activity against the α-amylase of the mealworm beetle, Tenebrio molitor (TMA) with the latter showing enhanced activity. The human salivary as well as barley α-amylase activities were not inhibited even at concentrations of up to 50 μM, which has been predicted to be due to differences in the pocket size and the size of the interacting loops. Present study shows that the variant Alpha-TvD1 exhibits enhanced antifungal as well as insect α-amylase inhibitory activity.
authors.affiliation: Department of Plant Sciences, University of Hyderabad, Hyderabad 500046, India.
authors.forename: S
authors.initials: S
authors.lastname: Vijayan
authors.forename: J
authors.initials: J
authors.lastname: Imani
authors.forename: K
authors.initials: K
authors.lastname: Tanneeru
authors.forename: L
authors.initials: L
authors.lastname: Guruprasad
authors.forename: K H
authors.initials: KH
authors.lastname: Kogel
authors.forename: P B
authors.initials: PB
authors.lastname: Kirti
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D000935:Antifungal Agents / Q000737:chemistry / Q000494:pharmacology*; D020134:Catalytic Domain; D002686:Chitin / Q000378:metabolism; D005658:Fungi / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D006801:Humans; D020128:Inhibitory Concentration 50; D019476:Insect Proteins / Q000037:antagonists & inhibitors* / Q000737:chemistry; D007306:Insecticides / Q000737:chemistry / Q000494:pharmacology*; D007814:Larva / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010539:Permeability; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*; D011485:Protein Binding; D044224:Pseudomonas syringae / Q000187:drug effects; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology; D013172:Spores, Fungal / Q000187:drug effects; D013712:Tenebrio / Q000201:enzymology; D031304:Tephrosia; D000516:alpha-Amylases / Q000037:antagonists & inhibitors* / Q000737:chemistry; D023084:alpha-Defensins / Q000737:chemistry / Q000235:genetics / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D000935:Antifungal Agents; D019476:Insect Proteins; D007306:Insecticides; D010940:Plant Proteins; D011994:Recombinant Proteins; D023084:alpha-Defensins; D002686:Chitin; D000516:alpha-Amylases