Degradation of Nematodes by Chitinase AO-492 from Arthrospora oligospora
[Objective]To explore the biological function of secreted protein AO-492 in the process of chitin induction from nematode-trapping fungus Arthrobotrys oligospora.[Method]The coding region of the main domain of chitinase AO-492 from A.oligospora was cloned and analyzed,and expressed in Pichia pastoris.The recombinant protein ReAO-Z492 was purified by nickel column affinity chromatography.The enzymatic activity of the recombinant protein under different temperature,pH and metal ion conditions was analyzed by NAG assay,and its biological function was analyzed by acting on Caenorhabditis elegans and eggs.[Result]The chitinase AO-492 had a signal peptide,no transmembrane domain,contained two chitin binding domains and a glycoside hydrolase 18 family domain,and the highly conserved substrate binding site of the glycoside hydrolase 18 family chitinase-SVGGWT-and the hydrolase active site-FDGGDLDWE-,as well as a typical TIM barrel molecular structure.Phylogenetic analysis showed that the protein had the closest genetic relationship with chitinase(EPS35099.1).SDS-PAGE and Western Blot analysis showed that the molecular weight of ReAO-Z492 was about 59 kD,which specifically reacted with mouse polyclonal antibody against A.oligospora.The optimal temperature and pH of ReAO-Z492 were 40℃and 7.0,respectively.Mg2+promoted the enzyme activity,while Ag+,Cu2+,Fe3+and Zn2+inhibited it.ReAO-Z492 had strong degrading activity on the body wall and egg shell of C.elegans.[Conclusion]The chitinase AO-492 of A.oligospora has a strong degradation effect on C.elegans and its eggs.
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