烟曲霉pbs2基因功能初步探讨

目的 克隆烟曲霉pbs2基因,并构建烟曲霉pbs2基因突变株,了解该基因对烟曲霉形态学影响以及对渗透压、氧化压力物质敏感性的变化.方法 通过基因同源性比对,在烟曲霉基因组找出与酿酒酵母pbs2基因同源的序列,分析其结构并通过PCR扩增烟曲霉pbs2基因连同其上下游各约1.0 kb的DNA片段,将该片段重组到质粒pDHt/SK中形成PA,再通过PCR扩增pyrG作为筛选标记插入到PA的pbs2基因开放阅读框架(ORF)中,构建好pbs2基因敲除载体PB.将敲除载体转化到根瘤农杆菌,再利用ATMT法转化嘧啶营养缺陷株烟曲霉AF293.1,筛选出烟曲霉pbs2基因缺陷株△Pbs2.观察突变株和野生株AF293在基础培养基上的生长速度并测定二者对渗透压、氧化压力物质敏感性的变化.结果 经过SMART软件分析发现烟曲霉pbs2基因编码一种磷酸转移酶.在基础培养基上△pbs2生长速度同野生株间差异无统计学意义(P＞0.05),但在氧化压力和渗透压的信号传导中,△pbs2对氧化压力和渗透压的敏感性较野生株AF293敏感.结论 烟曲霉中pbs2基因不仅参与渗透压的传导,还参与氧化压力的传导,但只参与传导特定的氧化压力.

Cloning and functional analysis of pbs2 gene in Aspergillus fumigatus

Objective To construct a mutant strain of Aspergillus fumigatus with the mutant pbs2 gene, and to investigate the effect of the mutant gene on the morphology of A. fumigatus, the variation of os-motic pressure and the sensitivity of oxidative stress. Methods S. cerevisiae pbs2 gene homologs was identi-fied in A. fumigatus genome database. A PCR fragment, composed of the 5' flanking sequence(approximate-ly 1 kb) ofpbs20RF and its 3' flanking sequence (approximately 1 kb), was subcloned into a vector pDHt/SK with Xho Ⅰ/Xba Ⅰ enzyme to produce a recombinant plasmid PA. The selected marker pryG amplified from pLAX223 was cloned into PA with BamH Ⅰ/Pst Ⅰ enzyme to produce plasmid PB. PB was transformed into Agrobacterium tumefac/ens and named plasmid At pbs2. Then At pbs2 was transformed into A. fumigatus strain AF293.1 (pyrG) via ATMT to produce the transformants △pbs2. To observe the growth rate and the phenotype on the MM containing different oxidative stress and osmotic pressure between the △pbs2 and the wild type. Results There were no visible difference between △pbs2 and AF293 on the radial growth rate and morphology. △pbs2 mutant was not only more sensitive to osmotic pressure produced by sodium chloride and glycerol but also sensitive to oxidative stress produced by hydrogen peroxide than the wild type. Conclu-sion The pbs2 gene plays a role in osmotic pressure and oxidative stress signal tmnsductions in A. fumiga-tus but only involved in oxidative stress induced by hydrogen peroxide specifically. However, pbs2 gene has a minor effect on growth and morphology in A. fumigatus.