TN3 TRANSPOSITION IMMUNITY: A NEW GENETIC PHENOMENON

转座免疫是一种相对未研究的遗传现象， 细菌Tn3转座免疫是一种顺式作用机制， Tn3插入质粒。 我们已经证明Tn3的末端重复序列可以 赋予质粒免疫力。 然而，我们也发现， 免疫表型可受宿主序列影响。 在此授予 在此期间，我们将采用基因方法，使用体外技术， 体内诱变，以剖析免疫序列以及宿主， 也影响免疫力的质粒序列。 我们将决定 与Tn3相关的其他转座子显示免疫性，如果是，则确定是否 它们对彼此表现出交叉免疫 我们将确定一个 DNA分子Tn3可以赋予免疫力以及是否存在其他参数 这也影响免疫力。 例如，一些天然存在的质粒 尽管它们不会产生青霉素耐药性，但对Tn3具有免疫力。 通过 这种遗传方法，以及额外的实验，我们将 区分换位免疫如何工作的各种模型。

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.