Courcelle J, Ganesan A K, Hanawalt P C
Department of Biological Sciences; Mississippi State University, 39762, USA.
Bioessays. 2001 May;23(5):463-70. doi: 10.1002/bies.1065.
The order of discovery can have a profound effect upon the way in which we think about the function of a gene. In E. coli, recA is nearly essential for cell survival in the presence of DNA damage. However, recA was originally identified, as a gene required to obtain recombinant DNA molecules in conjugating bacteria. As a result, it has been frequently assumed that recA promotes the survival of bacteria containing DNA damage by recombination in which DNA strand exchanges occur. We now know that several of the processes that interact with or are controlled by recA, such as excision repair and translesion synthesis, operate to ensure that DNA replication occurs processively without strand exchanges. Yet the view persists in the literature that recA functions primarily to promote recombination during DNA repair. With the benefit of hindsight and more than three decades of additional research, we reexamine some of the classical experiments that established the concept of DNA repair by recombination, and we consider the possibilities that recombination is not an efficient mechanism for rescuing damaged cells, and that recA may be important for maintaining processive replication in a manner that does not generally promote recombination.
发现的顺序可能会对我们思考基因功能的方式产生深远影响。在大肠杆菌中，recA在存在DNA损伤的情况下对细胞存活几乎至关重要。然而，recA最初被鉴定为在接合细菌中获得重组DNA分子所需的基因。因此，人们经常认为recA通过发生DNA链交换的重组来促进含有DNA损伤的细菌的存活。我们现在知道，与recA相互作用或受其控制的几个过程，如切除修复和跨损伤合成，其作用是确保DNA复制连续进行而不发生链交换。然而，文献中仍然存在这样的观点，即recA主要在DNA修复过程中促进重组。借助事后诸葛亮的优势以及三十多年的额外研究，我们重新审视了一些确立了通过重组进行DNA修复概念的经典实验，并考虑了以下可能性：重组不是拯救受损细胞的有效机制，并且recA可能以一种通常不促进重组的方式对维持连续复制很重要。
