Physiological Control of Mu-dependent DNA Rearrangements

“Mu依赖性DNA重排的生理控制”大肠杆菌和Mu遗传学将用于解剖阿拉伯- lacz融合系统，这是细菌中生理调节突变（“适应性突变”）的第一个严格记录的例子。在这个系统中，Mu噬菌体通过连接部分阿拉伯和lacA顺子形成杂交蛋白编码序列。使用非致死性Mu B-KAN（7701）噬菌体进行的融合研究发现了在实际融合形成之前激活状态的证据，并表明融合动力学是在两个不同的水平上决定的：(1)Mu激活/抑制和(2)在Mu促进的DNA重排列中链转移复合物中间体的差异加工。该项目将利用分子遗传技术和我们操纵细菌和Mu噬菌体基因组的能力来实现两个特定目标：(1)确定B-KAN（7701）菌株热抑制形成的预融合中间体的性质；(2)确定控制融合形成的信号转导系统中的分子。这些研究将扩展我们对细菌和其他活细胞如何能够修改其基因组结构的理解。特别是，它将阐明细胞生长条件的差异如何激活和影响所有生物体拥有的自然基因工程系统。这项研究将为进化过程和我们改造细胞用于生物技术的能力提供新的线索。＊＊＊

Shapiro 9513728 "Physiological control of Mu-dependent DNA rearrangements" E. coli and Mu genetics will be used to dissect the araB-lacZ fusion system, the first rigorously documented example of physiologically-regulated mutation in bacteria ("adaptive mutation"). In this system, a Mu prophage forms a hybrid protein coding sequence by joining portions of the araB and lacA cistrons. Fusion studies using a non-lethal Mu B-KAN(7701 prophage have uncovered evidence for an activated state preceeding actual fusion formation and suggested that fusion kinetics are determined at two different levels: (1) Mu activation/derepression and (2) differential processing of the strand-transfer complex intermediate in Mu-promoted DNA rearrangements. This project will capitalize on molecular genetic technology and our ability to manipulate both the bacterial and Mu prophage genomes to accomplish two specific aims: (1) identify the nature of pre-fusion intermediates formed by thermal derepression of B-KAN(7701 strains, and (2) identify molecules in the signal transduction system controlling fusion formation. These studies will extend our understanding of how bacteria and other living cells are able to modify the structures of their genomes. In particular, it will illuminate how differences in cellular growth conditions activate and influence the natural genetic engineering systems which all organisms possess. This research will shed new light on evolutionary processes and our ability to modify cells for use in biotechnology. ***