Molecular Studies of Chromosomal Protein H-NS"

染色体的分子结构仍然是现代遗传学的主要谜团之一。尽管在学习染色体的核苷酸序列方面取得了令人印象深刻的进展，但将功能DNA包装到可用的小空间中的机制尚未解决。一种组织机制是超盘绕。DNA在所有生物体中都是超盘绕的，其程度大致相同。另一个令人困惑的事实是，在任何时刻，只有一小部分遗传信息被积极使用。了解DNA是如何在染色体的活跃区域和非活跃区域组织的被称为结构域问题。噬菌体MU是研究染色体结构最有用的工具之一。Mu是一种转座子，它随机地将自己插入细菌染色体中，并利用宿主酶和蛋白质创造自己的超螺旋结构域。此外，通过新的Mu遗传学，发现大肠杆菌中最丰富的染色体蛋白之一H-NS，超级螺旋DNA。被H-NS缠绕的DNA不具有转录活性。因此，H-NS是组织非活性超螺旋结构域的主要候选者。实验旨在利用遗传方法以及化学和酶探针和电子显微镜来探测H-NS与Mu DNA相互作用的结构。

Molecular architecture of chromosomes remains one of the major mysteries of modern genetics. In spite of impressive advances made in learning the nucleotide sequence of chromosomes, the mechanisms of packing functional DNA into the small space available is unsolved. One organizing mechanism is supercoiling. DNA is found supercoiled in all organisms to about the same extent. Another puzzle is the fact that only a fraction of the genetic information is actively used at any instant. Learning how DNA is organized in both active and inactive regions of chromosomes is known as the domain problem. Bacteriophage MU is one of the most useful tools for studying chromosome structure. Mu is a transposon that randomly inserts itself into bacterial chromosomes and creates its own supercoiled domain using host enzymes and proteins. Further, through novel Mu genetics, it was discovered that one of the most abundant chromosomal proteins in E. coli, H-NS, supercoils DNA. DNA supercoiled by H-NS is inactive for transcription. Thus, H-NS is a prime candidate for organizing inactive supercoiled domains. Experiments are designed to probe the structure of H-NS interactions with Mu DNA using genetic approaches as well as chemical and enzymatic probes and electron microscopy.