Lampe D J, Grant T E, Robertson H M
Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
Genetics. 1998 May;149(1):179-87. doi: 10.1093/genetics/149.1.179.
Mariner family transposable elements are widespread in animals, but their regulation is poorly understood, partly because only two are known to be functional. These are particular copies of the Dmmar1 element from Drosophila mauritiana, for example, Mos1, and the consensus sequence of the Himar1 element from the horn fly, Haematobia irritans. An in vitro transposition system was refined to investigate several parameters that influence the transposition of Himar1. Transposition products accumulated linearly over a period of 6 hr. Transposition frequency increased with temperature and was dependent on Mg2+ concentration. Transposition frequency peaked over a narrow range of transposase concentration. The decline at higher concentrations, a phenomenon observed in vivo with Mos1, supports the suggestion that mariners may be regulated in part by "overproduction inhibition." Transposition frequency decreased exponentially with increasing transposon size and was affected by the sequence of the flanking DNA of the donor site. A noticeable bias in target site usage suggests a preference for insertion into bent or bendable DNA sequences rather than any specific nucleotide sequences beyond the TA target site.
水手家族转座元件在动物中广泛存在，但其调控机制却鲜为人知，部分原因是已知只有两个元件具有功能。例如，来自毛里求斯果蝇的Dmmar1元件的特定拷贝Mos1，以及来自角蝇（嗜人血蝇）的Himar1元件的共有序列。一种体外转座系统得到了优化，以研究影响Himar1转座的几个参数。转座产物在6小时内呈线性积累。转座频率随温度升高而增加，并且依赖于Mg2+浓度。转座频率在转座酶浓度的一个狭窄范围内达到峰值。在较高浓度下出现下降，这一在Mos1体内观察到的现象支持了水手元件可能部分受“过量产生抑制”调控的观点。转座频率随转座子大小增加呈指数下降，并且受供体位点侧翼DNA序列的影响。在靶位点使用上存在明显偏差，这表明其倾向于插入弯曲或可弯曲的DNA序列，而不是TA靶位点之外的任何特定核苷酸序列。
