尖孢镰刀菌FoHeli转座元件的结构特征及功能验证

Structural characteristics and functional identification of FoHeli transposable element in Fusarium oxysporum

Helitron是一种广泛存在于真核生物中的可移动遗传元件。与其他转座子不同,自主Helitron元件可编码具有复制引发(Rep)和解旋酶(Hel)结构域的转座酶,并通过滚环复制的方式在基因组中进行扩张。本研究对9种尖孢镰刀菌中的自主Helitron元件进行系统分析,结果表明尖孢镰刀菌中存在两类自主Helitron元件FoHeli1与FoHeli2。其中FoHeli1成员间序列高度相似,并具有明晰的边界特征:3’端为保守的"TATTTT"序列,其上游可形成稳定的发夹结构,且发夹上游可与5’端形成12bp的反向互补结构。基于上述分析结果,从尖孢镰刀菌Fo4287菌株中克隆获得完整的Fo Heli1元件,并通过构建双元转座系统及PEG介导的原生质体转化,证明尖孢镰刀菌中的Fo Heli元件可在禾谷镰刀菌PH-1菌株的基因组中发生跳转。

Helitron is a family of transposable element in eukaryotes.Unlike other transposons,Helitron can encode a replication initiator protein（Rep）and a helicase（Hel）,and expand in the genome by rolling circle replication.This study systematically analyzed the autonomous Helitron elements in nine Fusarium oxysporum strains.The generation of evolutionary trees indicated that there were two types of Helitron,i.e.,FoHeli1 and FoHeli2.The sequences are highly similar and boundary is clear between the members of FoHeli1.There is a conserved motif＂TATTTT＂at the 3′-end,a hairpin of the 3′-end upstream and 12bp inverted repeats making upstream of hairpin and 5′-end pairing with each other.Based on above analytic results,the Fo Heli1 element was cloned from the F.oxysporum strain Fo4287,and the transposable ability of FoHeli element was verified through construction of the dual translocation system and PEG mediated protoplast transformation of F.graminearum PH-1 strain.