Abstract: The AmPR-10（Astragalus membranaceus pathogenesis-related protein-10）plays an important role in the development and disease resistance of Astragalus membranaceus. The results showed that the AmPR-10 expressed in E. coli could display nuclease activity. Comparing the amino acid sequence of AmPR-10 with its seven homologous proteins which had been proved to have nuclease activity, we found that there were four highly conserved regions in the AmPR-10 gene (V14-V24, V44-K55, T64-K70 and Y83-G88 ). The first conserved region and the C-terminal α-helix formed a strong hydrophobic region in space to stabilize the structure of protein cavity, which was conducive to the function of AmPR-10 in resisting invasion. In addition, by molecular docking and amino acid site mutation, the Tyr at position 83 in the fourth conserved region was discovered to be the key site for AmPR-10 nuclease activity, and its change would affect the stability of target protein binding with substrate, while the 140 Gly in the non-conservative region could be used as a reference site for gene evolution. When Gly was mutated to Asn, Val and Trp, the binding free energy was decreased. The above results have theoretical guiding significance for further understanding and optimizing of the nuclease activity of AmPR-10.

Key words: AmPR-10, homologous protein, molecular docking, nuclease activity