黄曲霉Ste50衔接子蛋白对生长发育及致病性的影响

Effects of adaptor protein Ste50 on growth, development and pathogenicity of Aspergillus flavus

摘要:

[目的] Ste50是真菌中重要的衔接子蛋白，在多个MAPK级联通路中起重要的信号衔接与传递作用。本研究鉴定出了黄曲霉AflSte50蛋白，并发现了其对黄曲霉的生长、产孢、致病能力和响应渗透压胁迫等方面的影响。[方法] 首先通过生物信息学方法在黄曲霉NRRL 3357中鉴定出ste50基因，并通过同源重组的方法构建了ste50基因的敲除和互补突变体菌株。而后，对基因敲除在黄曲霉生长发育、次级代谢产物合成和胁迫响应等方面的作用进行了研究。[结果] 与野生型相比，△Aflste50菌株生长速度和AFB₁合成量降低且不能产生菌核，同时对花生、玉米种子的致病能力下降。该基因在渗透胁迫条件下正调控MAP激酶的磷酸化水平，但对细胞壁胁迫无响应。[结论] Ste50（AFLA_002340）是黄曲霉衔接子蛋白，影响黄曲霉的生长、发育和AFB₁的合成，能够响应渗透压胁迫，在HOG通路中发挥作用。

Abstract:

[Objective] Ste50 is an important adaptor protein in fungi, which plays important roles in signal connection and transmission in multiple MAPK pathways. In this study, Aflste50 protein of Aspergillus flavus was identified and its effects on growth, conidiation, pathogenicity and response to osmotic stress were found. [Methods] Firstly, the ste50 gene was identified in A. flavus NRRL 3357 by bioinformatics method. Then, the effect of gene knockout on growth, secondary metabolite synthesis and stress response of A. flavus were tested. [Results] Compared with the wild type, the growth rate and AFB₁ synthesis of △Aflste50 strain were decreased. And sclerotia formation of A. flavus was blocked when ste50 was absent. At the same time, the pathogenicity to peanut and maize seeds was impaired in △Aflste50. Also, AflSte50 regulated the phosphorylation of MAP kinase under osmotic stress, but did not respond to cell wall stress.[Conclusion] Ste50 (AFLA_ 002340) is an adaptor protein of A. flavus, which affects the growth and development, as well as the synthesis of AFB₁ in this fungus. It can respond to osmotic stress and play a role in the HOG pathway.