The roles of purified Int and Xis proteins of the conjugative transposon Tn 916 in excision of a deletion derivative of the closely related element Tn 1545 were investigated. At a low salt concentration (37.5 mM NaCl), Int alone was able to promote limited excision to produce a covalently closed circular form of the transposon, showing that Tn 916 Int can catalyze both DNA cleavage and strand exchange. This reaction was stimulated by Xis. At higher salt concentrations (150 mM NaCl), excision by Int alone was reduced to barely detectable levels and Xis was required for excision. The low salt, Xis-stimulated reaction was approximately 8-fold more efficient than the high salt, Xis-dependent reaction. These results reflect in vivo requirements for Int and Xis in excision.
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机译：研究了共轭转座子Tn 916的纯化的Int和Xis蛋白在切除紧密相关元件Tn 1545的缺失衍生物中的作用。在低盐浓度（37.5 mM NaCl）下，单独的Int能够促进有限的切除以产生共价闭合的转座子环状形式，表明Tn 916 Int可以催化DNA切割和链交换。 Xis刺激了这一反应。在更高的盐浓度（150 mM NaCl）下，仅通过Int进行的切除就减少到几乎检测不到的水平，并且需要Xis进行切除。低盐Xis刺激的反应比高盐Xis依赖性反应的效率高约8倍。这些结果反映了体内对Int和Xis的切除要求。
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