雪腐核盘菌ClyA_Cry6Aa-like成孔毒素蛋白功能OA

Pore-forming toxins(PFTs)are present in fungi,but their functions remain poorly understood.In this study,analysis of differentially expressed genes between sclerotia and mycelia of Sclerotinia nivalis revealed that genes encoding pore-forming toxin proteins were highly expressed in sclerotia.Further proteomic profiling by mass spectrometry confirmed the abundant accumulation of these proteins in sclerotia.Sequence and structural analyses indicated that three pore-forming toxin proteins SnCry6Aa1,SnCry6Aa2,and SnCry6Aa3 were encoded by S.nivali SnTB1.All of which contain the conserved ClyA_Cry6Aa-like PFTs domain and exhibit the characteristic three-dimensional structure of α-PFTs.The recombinant SnCry6Aa1 and SnCry6Aa2 were successfully expressed and purified using a prokaryotic system,and their hemolytic activity and nematidal/insecticidal toxicity were subsequently assessed.The results showed that SnCry6Aa1 exhibited significant hemolytic activity at concentrations over 6.25 ng/mL under acidic conditions,whereas no similar activity was detected for SnCry6Aa2.Neither SnCry6Aa1 nor SnCry6Aa2 showed notable toxicity against Caenorhabditis elegans,Helicoverpa armigera,Spodoptera litura,Grapholita molesta,or Bradysia odoriphaga.However,both displayed low but detectable insecticidal activity against larvae of Pnyxia scabiei,with corrected mortality rates of 14%and 17%,respectively.This study is the first to identify the presence of ClyA_Cry6Aa-like PFTs at high abundance in the sclerotia of S.nivalis and provides initial insights into their biological roles,laying a foundation for further functional studies and potential applications of these proteins.