Finkel S E, Johnson R C
Department of Biological Chemistry, UCLA School of Medicine 90024-1737.
Mol Microbiol. 1992 Nov;6(22):3257-65. doi: 10.1111/j.1365-2958.1992.tb02193.x.
Higher-order nucleoprotein complexes are associated with many biological processes. In bacteria the formation of these macromolecular structures for DNA recombination, replication, and transcription often requires not only the participation of specific enzymes and co-factors, but also a class of DNA-binding proteins collectively known as 'nucleoid-associated' or 'histone-like' proteins. Examples of this class of proteins are HU, Integration Host Factor, H-NS, and Fis. Fis was originally identified as the factor for inversion stimulation of the homologous Hin and Gin site-specific DNA recombinases of Salmonella and phage Mu, respectively. This small, basic, DNA-bending protein has recently been shown to function in many other reactions including phage lambda site-specific recombination, transcriptional activation of rRNA and tRNA operons, repression of its own synthesis, and oriC-directed DNA replication. Cellular concentrations of Fis vary tremendously under different growth conditions which may have important regulatory implications for the physiological role of Fis in these different reactions. The X-ray crystal structure of Fis has been determined and insights into its mode of DNA binding and mechanisms of action in these disparate systems are being made.
高阶核蛋白复合物与许多生物过程相关。在细菌中，这些用于DNA重组、复制和转录的大分子结构的形成通常不仅需要特定酶和辅助因子的参与，还需要一类统称为“类核相关”或“组蛋白样”的DNA结合蛋白。这类蛋白的例子有HU、整合宿主因子、H-NS和Fis。Fis最初分别被鉴定为沙门氏菌和噬菌体Mu同源Hin和Gin位点特异性DNA重组酶的倒位刺激因子。这种小的碱性DNA弯曲蛋白最近被证明在许多其他反应中发挥作用，包括噬菌体λ位点特异性重组、rRNA和tRNA操纵子的转录激活、自身合成的抑制以及oriC导向的DNA复制。在不同生长条件下，Fis的细胞浓度差异极大，这可能对Fis在这些不同反应中的生理作用具有重要的调节意义。Fis的X射线晶体结构已被确定，并且正在深入了解其DNA结合模式以及在这些不同系统中的作用机制。
