Soyuretox, an Intrinsically Disordered Polypeptide Derived from Soybean (Glycine Max) Ubiquitous Urease with Potential Use as a Biopesticide

Abstract

Ureases from different biological sources display non-ureolytic properties that contribute to plant defense, in addition to their classical enzymatic urea hydrolysis. Antifungal and entomotoxic effects were demonstrated for Jaburetox, an intrinsically disordered polypeptide derived from jack bean (Canavalia ensiformis) urease. Here we describe the properties of Soyuretox, a polypeptide derived from soybean (Glycine max) ubiquitous urease. Soyuretox was fungitoxic to Candida albicans, leading to the production of reactive oxygen species. Soyuretox further induced aggregation of Rhodnius prolixus hemocytes, indicating an interference on the insect immune response. No relevant toxicity of Soyuretox to zebrafish larvae was observed. These data suggest the presence of antifungal and entomotoxic portions of the amino acid sequences encompassing both Soyuretox and Jaburetox, despite their small sequence identity. Nuclear Magnetic Resonance (NMR) and circular dichroism (CD) spectroscopic data revealed that Soyuretox, in analogy with Jaburetox, possesses an intrinsic and largely disordered nature. Some folding is observed upon interaction of Soyuretox with sodium dodecyl sulfate (SDS) micelles, taken here as models for membranes. This observation suggests the possibility for this protein to modify its secondary structure upon interaction with the cells of the affected organisms, leading to alterations of membrane integrity. Altogether, Soyuretox can be considered a promising biopesticide for use in plant protection.

Structure-Function Insights of Jaburetox and Soyuretox: Novel Intrinsically Disordered Polypeptides Derived from Plant Ureases

“…Interestingly, both microorganisms are susceptible to Jaburetox [60,61]. [77]; (4) Fruttero et al, [82]; (5) Coste Grahl et al, [83]; (6) Kappaun et al, [64]; (7) and (8) unpublished results; (9) Staniscuaski et al, [81].…”

“…Soyuretox became more globular in solution and showed changes in its secondary structure, with loss of helices and beta strands. [58,64] Dynamic Light Scattering and Small Angle X-ray Scattering Dynamic Light Scattering Jaburetox Jaburetox Demonstrated the ability of Jaburetox to interact with lipids using platelet-like multilamellar liposomes (PML). Jaburetox in a neutral solution is found in a single oligomeric form, exhibiting a large hydrodynamic radius, suggestive of a disordered polypeptide.…”

“…Our data suggest that these peptides probably interact with lipids in the fungal membrane (Figure 4). Although it still lacks experimental demonstration, it is (3) Moyetta et al, [77]; (4) Fruttero et al, [82]; (5) Coste Grahl et al, [83]; (6) Kappaun et al, [64]; (7) and (8) unpublished results; (9) Staniscuaski et al, [81].…”

“…The participation of ureases in plant defense against fungal diseases was demonstrated in urease-null soybean plants obtained by gene silencing [ 63 ]. Later, the peptide called Soyuretox, homologous to Jaburetox, but derived from the ubiquitous isoform of the soybean urease, was heterologously expressed in E. coli , characterized structurally and its entomotoxic and antifungal effects were demonstrated [ 64 ].…”

“…Jaburetox showed no acute toxicity to mice and rats [ 57 ] and was found not toxic in a risk assessment study [ 65 ] while Soyuretox was not toxic to zebrafish embryos [ 64 ]. These data suggest that these peptides may be safe alternatives to attain resistance to insect herbivory and/or fungal disease in transgenic plants.…”