Laptenko Oleg, Kim Seung-Sup, Lee Jookyung, Starodubtseva Marina, Cava Fellipe, Berenguer Jose, Kong Xiang-Peng, Borukhov Sergei
Department of Cell Biology, School of Osteopathic Medicine at Stratford, University of Medicine and Dentistry of New Jersey, Stratford, NJ 08084, USA.
EMBO J. 2006 May 17;25(10):2131-41. doi: 10.1038/sj.emboj.7601094. Epub 2006 Apr 20.
Gfh1, a transcription factor from Thermus thermophilus, inhibits all catalytic activities of RNA polymerase (RNAP). We characterized the Gfh1 structure, function and possible mechanism of action and regulation. Gfh1 inhibits RNAP by competing with NTPs for coordinating the active site Mg2+ ion. This coordination requires at least two aspartates at the tip of the Gfh1 N-terminal coiled-coil domain (NTD). The overall structure of Gfh1 is similar to that of the Escherichia coli transcript cleavage factor GreA, except for the flipped orientation of the C-terminal domain (CTD). We show that depending on pH, Gfh1-CTD exists in two alternative orientations. At pH above 7, it assumes an inactive 'flipped' orientation seen in the structure, which prevents Gfh1 from binding to RNAP. At lower pH, Gfh1-CTD switches to an active 'Gre-like' orientation, which enables Gfh1 to bind to and inhibit RNAP.
嗜热栖热菌的转录因子Gfh1可抑制RNA聚合酶（RNAP）的所有催化活性。我们对Gfh1的结构、功能以及可能的作用和调控机制进行了表征。Gfh1通过与NTP竞争以配位活性位点Mg2+离子来抑制RNAP。这种配位需要Gfh1 N端卷曲螺旋结构域（NTD）末端至少两个天冬氨酸。Gfh1的整体结构与大肠杆菌转录切割因子GreA相似，只是C端结构域（CTD）的方向相反。我们发现，根据pH值，Gfh1-CTD存在两种不同的方向。在pH高于7时，它呈现出结构中所见的无活性“翻转”方向，这会阻止Gfh1与RNAP结合。在较低pH值下，Gfh1-CTD会转变为活性“Gre样”方向，使Gfh1能够结合并抑制RNAP。
