TN3 TRANSPOSITION IMMUNITY: A NEW GENETIC PHENOMENON

移位免疫是一种相对未被研究的遗传现象。 细菌。Tn3转位免疫是一种顺式作用机制，它限制 将Tn3插入到质粒中。我们已经证明了Tn3‘S末端重复序列可以 赋予对质粒的免疫力。然而，我们也发现，移位 免疫表型会受到寄主序列的影响。在此授予过程中 期间，我们将采用遗传方法，使用体外和 体内诱变，剖析免疫序列以及宿主和 也会影响免疫力的质粒序列。我们将确定是否 与Tn3相关的其他转座子表现出免疫力，如果是这样的话，确定 他们对彼此表现出交叉豁免权。我们将确定一个多大的 DNA分子Tn3是否能赋予免疫力以及是否还有其他参数 这也会影响豁免权。例如，一些自然产生的质粒 对Tn3免疫，但不会产生青霉素耐药性。穿过 这种遗传方法，以及额外的实验，我们将 区分转位免疫如何发挥作用的各种模型。

Transposition immunity is a relatively unstudied genetic phenomenon in bacteria. Tn3 transposition immunity is a cis acting mechanism which limits Tn3 insertion into a plasmid. We have shown that Tn3's terminal repeat can confer immunity to a plasmid. However, we also find that the transposition immunity phenotype can be affected by host sequences. During this granting period we will pursue a genetic approach, using techniques of in vitro and in vivo mutagenesis, to dissect the immunity sequence as well as host and plasmid sequences which also affect immunity. We will determine whether other transposons related to Tn3 show immunity and if so determine whether they show cross immunity to each other. We will determine to how large a DNA molecule Tn3 can confer immunity and whether there are other parameters which also affect immunity. For example, some naturally occurring plasmids are immune to Tn3 though they do not confer penicillin resistance. Through this genetic approach, as well as additional experiments, we will distinguish between the various models for how transposition immunity works.