Labrador M, Corces V G
Department of Biology, Johns Hopkins University, Baltimore, Maryland 21218, USA.
Annu Rev Genet. 1997;31:381-404. doi: 10.1146/annurev.genet.31.1.381.
Transposable elements propagate by inserting into new locations in the genomes of the hosts they inhabit. Their transposition might thus negatively affect the fitness of the host, suggesting the requirement for a tight control in the regulation of transposable element mobilization. The nature of this control depends on the structure of the transposable element. DNA elements encode a transposase that is necessary, and in most cases sufficient, for mobilization. In general, regulation of these elements depends on intrinsic factors with little direct input from the host. Retrotransposons require an RNA intermediate for transposition, and their frequency of mobilization is controlled at multiple steps by the host genome by regulating both their expression levels and their insertional specificity. As a result, a symbiotic relationship has developed between transposable elements and their host. Examples are now emerging showing that transposons can contribute significantly to the well being of the organisms they populate.
转座元件通过插入它们所寄生宿主基因组的新位置来进行增殖。因此，它们的转座可能会对宿主的适应性产生负面影响，这表明在转座元件动员的调控中需要严格控制。这种控制的性质取决于转座元件的结构。DNA元件编码一种转座酶，该转座酶对于转座是必需的，并且在大多数情况下足以实现转座。一般来说，这些元件的调控取决于内在因素，宿主的直接影响很小。逆转座子转座需要RNA中间体，宿主基因组通过调节其表达水平和插入特异性，在多个步骤控制它们的转座频率。结果，转座元件与其宿主之间形成了一种共生关系。现在有例子表明，转座子可以对它们所寄生的生物体的健康做出重大贡献。
