Study On Structure And Function Of Nucleoside Diphosphae Kinase(NDK) In Aspergillus Flavus

Aspergillus flavus and its secondary metabolite-aflatoxin,are serious threats for agricultural development and human health.Studies on the structure and function of proteins from A.flavus proteins are significant not only for the maintenance of food safety,but also for providing structural mechanism of Aspergillus flavus sopore growth and help for finding effective Aspergillus flavus inhibitors.Nucleoside Diphosphate Kinase(NDK)is a kind of phosphokinase which regulates the balance levels of intracellular nucleotide triphosphate between nucleoside triphosphate and nucleoside diphosphate by catalyzing the high-energy phosphate bond,and plays an important role in different organisms with a variety of functions.In this study,we found that NDK was the key protein in the growth of Aspergillus flavus:(1)There were double copies of ndk gene in the wide type of Aspergillus flavus.We knocked out one copy of ndk gene by homologous recombination method.The one-copy of ndk gene strain showed different phenotype compared with the wild type,expecially in the spore yield of the Aspergillus flavus and the growth of the conidiophore.(2)We found that zidovudine(AZT)inhibited the NDK protein activity in vitro,and inhibited the production of conidia and conidiophore in Aspergillus flavus.(3)In vitro,the NDK protein is expressed in E.coli and purified to a high level of purity by using a series of chromatograms,and 2.4 A resolution crystal diffraction data of the NDK protein was obtained by X-ray crystallography.The NDK folded into 25 molecules with asymmetric unit.Therefore,we believe that NDK plays an important role in spore synthesis of Aspergillus flavus.AZT can bind with NDK protein with high affinity,and may become a potential inhibitor of Aspergillus flavus.