沿DNA运动的蛋白机器如DNA聚合酶和解旋酶，必将遭遇与特定点发生相互作用的其他所结合的蛋白。Finkelstein等人利用由标记的DNA构成的纳米“帘子”来确定这种结合蛋白是否干涉细菌DNA转位酶RecBCD的活性。他们发现，这种酶非常“强健”，在它们被取代之前能将蛋白在非特定点上推动数千个碱基对的距离。（生物谷Bioon.com）
生物谷推荐原文出处：
Nature doi:10.1038/nature09561
Single-molecule imaging reveals mechanisms of protein disruption by a DNA translocase
Ilya J. Finkelstein,Mari-Liis Visnapuu& Eric C. Greene
In physiological settings, nucleic-acid translocases must act on substrates occupied by other proteins, and an increasingly appreciated role of translocases is to catalyse protein displacement from RNA and DNA1, 2, 3, 4. However, little is known regarding the inevitable collisions that must occur, and the fate of protein obstacles and the mechanisms by which they are evicted from DNA remain unexplored. Here we sought to establish the mechanistic basis for protein displacement from DNA using RecBCD as a model system. Using nanofabricated curtains of DNA and multicolour single-molecule microscopy, we visualized collisions between a model translocase and different DNA-bound proteins in real time. We show that the DNA translocase RecBCD can disrupt core RNA polymerase, holoenzymes, stalled elongation complexes and transcribing RNA polymerases in either head-to-head or head-to-tail orientations, as well as EcoRIE111Q, lac repressor and even nucleosomes. RecBCD did not pause during collisions and often pushed proteins thousands of base pairs before evicting them from DNA. We conclude that RecBCD overwhelms obstacles through direct transduction of chemomechanical force with no need for specific protein–protein interactions, and that proteins can be removed from DNA through active disruption mechanisms that act on a transition state intermediate as they are pushed from one nonspecific site to the next.
