- Cyclo(l-proline-l-serine) Dipeptide Suppresses Seed Borne Fungal Pathogens of Rice: Altered Cellular Membrane Integrity of Fungal Hyphae and Seed Quality Benefits
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Five proline-containing diketopiperazines (Pro-DKPs) produced by antagonistic microorganisms as secondary metabolites were selected and synthesized under laboratory conditions. Out of five synthesized Pro-DKPs, cyclo(l-Pro-l-Ser) (DKP-6) revealed the best inhibition of fungal pathogens (Fusarium verticillioides and Fusarium fujikuroi) of rice under in vitro conditions with effective doses lower than standard fungicide carbendazim. DKP-6 induced stress on the fungal cell membrane integrity, which was revealed by calcofluor white and propidium iodide assays, endorsed by ultra-microscopic details and soluble protein leakage assays. In vivo seed treatment of infested rice seeds with DKP-6 at 2000 μg/mL for 10 h of seed treatment inflicted best reduction in seed rot and seedling blight with respect to control and carbendazim. Significant enhancement in seedling quality parameters were also observed. The work presented the strong influence of cyclo(l-Pro-l-Ser) as a mycocidal seed treatment agent better than synthetic toxic fungicides for rice.
- Poonia, Baninderjit Kaur,Sidhu, Anjali,Sharma, Anju Bala
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p. 2160 - 2168
(2022/02/23)
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- Functional identification and structure determination of two novel prolidases from cog1228 in the amidohydrolase superfamily
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Two uncharacterized enzymes from the amidohydrolase superfamily belonging to cog1228 were cloned, expressed, and purified to homogeneity. The two proteins, Sgx9260c (gi|44242006) and Sgx9260b (gi|44479596), were derived from environmental DNA samples originating from the Sargasso Sea. The catalytic function and substrate profiles for Sgx9260c and Sgx9260b were determined using a comprehensive library of dipeptides and N-acyl derivative of l-amino acids. Sgx9260c catalyzes the hydrolysis of Gly-l-Pro, l-Ala-l-Pro, and N-acyl derivatives of l-Pro. The best substrate identified to date is N-acetyl-l-Pro with a value of kcat/Km of 3 × 105 M -1 s-1. Sgx9260b catalyzes the hydrolysis of l-hydrophobic l-Pro dipeptides and N-acyl derivatives of l-Pro. The best substrate identified to date is N-propionyl-l-Pro with a value of kcat/Km of 1 × 105 M-1 s-1. Three-dimensional structures of both proteins were determined by X-ray diffraction methods (PDB codes 3MKV and 3FEQ). These proteins fold as distorted (β/α) 8-barrels with two divalent cations in the active site. The structure of Sgx9260c was also determined as a complex with the N-methylphosphonate derivative of l-Pro (PDB code 3N2C). In this structure the phosphonate moiety bridges the binuclear metal center, and one oxygen atom interacts with His-140. The α-carboxylate of the inhibitor interacts with Tyr-231. The proline side chain occupies a small substrate binding cavity formed by residues contributed from the loop that follows β-strand 7 within the (β/α)8-barrel. A total of 38 other proteins from cog1228 are predicted to have the same substrate profile based on conservation of the substrate binding residues. The structure of an evolutionarily related protein, Cc2672 from Caulobacter crecentus, was determined as a complex with the N-methylphosphonate derivative of l-arginine (PDB code 3MTW).
- Xiang, Dao Feng,Patskovsky, Yury,Xu, Chengfu,Fedorov, Alexander A.,Fedorov, Elena V.,Sisco, Abby A.,Sauder, J. Michael,Burley, Stephen K.,Almo, Steven C.,Raushel, Frank M.
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experimental part
p. 6791 - 6803
(2011/05/05)
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