title: Recombinant amaranth cystatin (AhCPI) inhibits the growth of phytopathogenic fungi.
abstract: Phytocystatins are cysteine proteinase inhibitors from plants implicated in defense mechanisms against insects and plant pathogens. We have previously characterized an amaranth cystatin cDNA and analyzed its response to different kinds of abiotic stress [37]. In order to characterize amaranth cystatin, the coding sequence was expressed in Escherichia coli using the pQE-2 vector. Recombinant cystatin was predominantly found in the soluble fraction of the cell extract. Large amounts (266 mgL(-1)) of pure recombinant protein were obtained by affinity chromatography in a single step of purification. The amaranth cystatin with a pI 6.8 and an apparent 28 kDa molecular mass inhibited papain (E.C.3.4.22.2) (Ki 115 nM), ficin (E.C.3.4.22.3) (Ki 325 nM) and cathepsin L (E.C.3.4.22.15) (Ki 12.7 nM) but not stem bromelain (E.C.3.4.22.32), and cathepsin B (E.C.3.4.22.1) activities, in colorimetric assays. Furthermore, it was able to arrest the fungal growth of Fusarium oxysporum, Sclerotium cepivorum and Rhyzoctonia solani. It was further demonstrated that recombinant AhCPI is a weak inhibitor of the endogenous cysteine proteinase activities in the fungal mycelium. These findings contribute to a better understanding of the amaranth cystatin activity and encourage further studies of this protein.
authors.affiliation: Departamento de Biotecnología y Bioquímica, Cinvestav, Km. 9.6 Libramiento Norte, A.P. 629, 36821 Irapuato, Gto., Mexico. svaldes@ira.cinvestav.mx <svaldes@ira.cinvestav.mx>
authors.forename: Silvia
authors.initials: S
authors.lastname: Valdes-Rodriguez
authors.forename: Alberto
authors.initials: A
authors.lastname: Cedro-Tanda
authors.forename: Victor
authors.initials: V
authors.lastname: Aguilar-Hernandez
authors.forename: Erick
authors.initials: E
authors.lastname: Cortes-Onofre
authors.forename: Alejandro
authors.initials: A
authors.lastname: Blanco-Labra
authors.forename: Armando
authors.initials: A
authors.lastname: Guerrero-Rangel
mesh_terms: D027721:Amaranthus / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology; D002846:Chromatography, Affinity; D015891:Cystatins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018076:DNA, Complementary; D018744:DNA, Plant; D004926:Escherichia coli; D005658:Fungi / Q000254:growth & development* / Q000472:pathogenicity; D017343:Genes, Plant; D007113:Immunity, Innate / Q000235:genetics*; D025282:Mycelium; D010935:Plant Diseases / Q000235:genetics* / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012995:Solubility
chemical_list: D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D018076:DNA, Complementary; D018744:DNA, Plant; D010940:Plant Proteins; D011994:Recombinant Proteins