title: Isolation of a new fungi and wound-induced chitinase class in corms of Crocus sativus.
abstract: In plants, various chitinases have been identified and categorized into several groups based on the analysis of their sequences and domains. We have isolated SafchiA, a novel class of chitinase from saffron (Crocus sativus L.). The cDNA encoding SafchiA is mainly expressed in roots and corms, and its expression is induced by elicitor treatment, methyl jasmonate, wounding, and by the fungi Fusarium oxysporum, Beauveria and Phoma sp., suggesting a defence role of the protein. Furthermore, in vitro assays with the recombinant native protein showed chitinolytic, and antifungal activity. The deduced protein shares high similarity with chitinases belonging to family 19 of glycosyl-hydrolases, although some changes in the enzyme active site are present. To explore the properties of SafchiA we have expressed recombinant SafchiA in Escherichia coli and generated four different mutants affected in residues involved in the catalytic activity. One glutamic acid essential for family 19 chitinases activity is not present in C. sativus chitinase suggesting that only one acidic residue is necessary for the enzyme activity, in a similar manner as family 18 glycosyl-hydrolases.
authors.affiliation: VITAB Laboratorios Polígono Industrial Garysol C/Pino, Albacete, Spain. gerencia@vitablaboratorios.com
authors.forename: Raquel Castillo
authors.initials: RC
authors.lastname: López
authors.forename: Lourdes
authors.initials: L
authors.lastname: Gómez-Gómez
mesh_terms: D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000494:pharmacology; D001203:Ascomycota / Q000187:drug effects / Q000502:physiology; D052982:Beauveria / Q000187:drug effects / Q000502:physiology; D002384:Catalysis; D020134:Catalytic Domain / Q000235:genetics; D002688:Chitinases / Q000145:classification / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D027622:Crocus / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D005670:Fusarium / Q000187:drug effects / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D054884:Host-Pathogen Interactions; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D010935:Plant Diseases / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D018514:Plant Structures / Q000201:enzymology* / Q000235:genetics / Q000382:microbiology; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013314:Stress, Mechanical
chemical_list: D000935:Antifungal Agents; D018076:DNA, Complementary; D010940:Plant Proteins; D011994:Recombinant Proteins; D002688:Chitinases