Cloning and expression of pathogenesis-related protein 4 from jelly fig (Ficus awkeotsang Makino) achenes associated with ribonuclease, chitinase and anti-fungal activities
ABSTRACT A cDNA fragment (FaPR4) encoding a class I pathogenesis-related protein 4 (PR-4) from Ficus awkeotsang was obtained by PCR cloning. Plant PR-4s were grouped into class I and II, differing by the presence of ChtBD and hinge. The predicted mature FaPR4 comprises N-terminal chitin-binding domain (ChtBD), hinge, Barwin domain and C-terminal extension. FaPR4-C, an N-terminal truncated form of FaPR4, was designed to mimic the structural feature of class II PR-4s. FaPR4 and FaPR4-C were over-expressed in yeast Pichia pastoris, and both recombinants exhibited RNase and anti-fungal activities. To our knowledge, it is the first report that FaPR4, a member of class I PR-4s has RNase activity as class II. FaPR4 possesses better anti-fungal activities toward Fusarium oxysporum and Sclerotium rolfsii than FaPR4-C. Heat-treated FaPR4 remained RNase and anti-fungal activities; while heat-treated FaPR4-C lost those activities. Therefore, ChtBD of FaPR4 may not only contribute to its anti-fungal but also improve the thermal stability of protein. It also implied the correlation of RNase activity with anti-fungal activity of FaPR4-C. Furthermore, FaPR4 was detected to have weak but significant chitinase activity, and its chitinase activity was reduced after heat treatment. The chitinase activity by FaPR4-C was much lower than FaPR4.
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- "The mechanism whereby PR4 proteins inhibit fungal growth occurs through chitinase (Ponstein et al., 1994; Lu et al., 2012) as well as RNase and DNase (Caporale et al., 2004; Bertini et al., 2009; Guevara-Morato et al., 2010; Li et al., 2010; Lu et al., 2012) activities. Although the purified recombinant LcPR4a inhibited A. lentis growth, its mode of action remains unknown and will be the subject of future studies. "
ABSTRACT: A novel pathogenesis-related protein 4 (PR4) encoding gene, LcPR4a, was induced in Lens culinaris following Ascochyta lentis infection. LcPR4a encodes a predicted 146 amino acid protein of 15.8 kDa. The putative LcPR4a protein belongs to the class II PR4 family and has close phylogenetic affinity to PR4 proteins from related species. qPCR analysis revealed differential expression of the LcPR4a gene upon Ascochyta lentis infection in both resistant and susceptible cultivars. This, combined with preliminary in vitro antifungal assays of the recombinant protein expressed in E. coli, suggests the potential important role of LcPR4a in the defence response of lentil to Ascochyta lentis attack.Phytopathologia Mediterranea 01/2013; 52(1):192-201. DOI:10.14601/Phytopathol_Mediterr-11791 · 1.29 Impact Factor
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ABSTRACT: Crop plants have evolved an array of mechanisms to counter biotic and abiotic stresses. Many pathogenesis-related proteins are expressed by plants during the attack of pathogens. Advances in recombinant DNA technology and understanding of plant-microbe interactions at the molecular level have paved the way for isolation and characterization of genes encoding such proteins, including chitinases. Chitinases are included in families 18 and 19 of glycosyl hydrolases (according to www.cazy.org ) and they are further categorized into seven major classes based on their aminoacid sequence homology, three-dimensional structures, and hydrolytic mechanisms of catalytic reactions. Although chitin is not a component of plant cell walls, plant chitinases are involved in development and non-specific stress responses. Also, chitinase genes sourced from plants have been successfully over-expressed in crop plants to combat fungal pathogens. Crops such as tomato, potato, maize, groundnut, mustard, finger millet, cotton, lychee, banana, grape, wheat and rice have been successfully engineered for fungal resistance either with chitinase alone or in combination with other PR proteins.Biotechnology Letters 06/2013; DOI:10.1007/s10529-013-1269-4 · 1.74 Impact Factor
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ABSTRACT: The first crystal structure of a barwin-like protein, named carwin, has been determined at high resolution by single-wavelength anomalous diffraction (SAD) phasing using the six intrinsic S atoms present in the protein. The barwin-like protein was purified from Carica papaya latex and crystallized in the orthorhombic space group P212121. Using in-house Cu Kα X-ray radiation, 16 cumulative diffraction data sets were acquired to increase the signal-to-noise level and thereby the anomalous scattering signal. A sequence-database search on the papaya genome identified two carwin isoforms of 122 residues in length, both containing six S atoms that yield an estimated Bijvoet ratio of 0.93% at 1.54 Å wavelength. A systematic analysis of data quality and redundancy was performed to assess the capacity to locate the S atoms and to phase the data. It was observed that the crystal decay was low during data collection and that successful S-SAD phasing could be obtained with a relatively low data multiplicity of about 7. Using a synchrotron source, high-resolution data (1 Å) were collected from two different crystal forms of the papaya latex carwin. The refined structures showed a central β-barrel of six strands surrounded by several α-helices and loops. The β-barrel of carwin appears to be a common structural module that is shared within several other unrelated proteins. Finally, the possible biological function of the protein is discussed.Acta Crystallographica Section D Biological Crystallography 10/2013; 69(Pt 10):2017-2026. DOI:10.1107/S0907444913018015 · 7.23 Impact Factor