Manna D, Higgins N P
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL 35294, USA.
Mol Microbiol. 1999 May;32(3):595-606. doi: 10.1046/j.1365-2958.1999.01377.x.
Transposition immunity is the negative influence that the presence of one transposon sequence has on the probability of a second identical element inserting in the same site or in sites nearby. A transposition-defective Mu derivative (MudJr1) produced transposition immunity in both directions from one insertion point in the Salmonella typhimurium chromosome. To control for the sequence preference of Mu transposition proteins, Tn10 elements were introduced as targets at various distances from an immunity-conferring MudJr1 element. Mu transposition into a Tn10 target was not detectable when the distance of separation from MudJr1 was 5 kb, and transposition was unencumbered when the separation was 25 kb. Between 5 kb and 25 kb, immunity decayed gradually with distance. Immunity decayed more sharply in a gyrase mutant than in a wild-type strain. We propose that Mu transposition immunity senses the domain structure of bacterial chromosomes.
转座免疫是指一个转座子序列的存在对第二个相同元件插入同一位置或附近位置的概率产生的负面影响。一种转座缺陷型Mu衍生物（MudJr1）在鼠伤寒沙门氏菌染色体的一个插入点两侧均产生了双向转座免疫。为了控制Mu转座蛋白的序列偏好，将Tn10元件作为靶标引入到距赋予免疫性的MudJr1元件不同距离处。当与MudJr1的间隔距离为5 kb时，未检测到Mu向Tn10靶标的转座，而当间隔距离为25 kb时，转座不受阻碍。在5 kb至25 kb之间，免疫随着距离逐渐衰减。在gyrase突变体中，免疫衰减比野生型菌株中更明显。我们提出，Mu转座免疫能够感知细菌染色体的结构域。
