Mustaev A, Kozlov M, Markovtsov V, Zaychikov E, Denissova L, Goldfarb A
Public Health Research Institute, 455 First Avenue, New York, NY 10016, USA.
Proc Natl Acad Sci U S A. 1997 Jun 24;94(13):6641-5. doi: 10.1073/pnas.94.13.6641.
The Fe2+ ion that specifically replaces Mg2+ in the active center of RNA polymerase generates reactive hydroxyl radicals that cause highly localized cleavage of polypeptide chains. Mapping of the cleavage sites revealed the overall architecture of the active center. Nine distinct sites, five in the beta subunit and four in the beta' subunit of Escherichia coli RNA polymerase, all at or near highly conserved sequence motifs, are brought together in the enzyme's ternary structure within the distance of approximately 1 nm from the active center Me2+. These sites are located in at least six different domains of the subunits, reflecting modular organization of the active center.
在RNA聚合酶活性中心特异性取代Mg2+的Fe2+离子会产生活性羟基自由基,导致多肽链发生高度局部的裂解。裂解位点的定位揭示了活性中心的整体结构。在大肠杆菌RNA聚合酶的β亚基中有五个不同的位点,β'亚基中有四个不同的位点,所有这些位点都位于高度保守的序列基序处或其附近,在酶的三元结构中,它们与活性中心Me2+的距离约为1纳米。这些位点位于亚基的至少六个不同结构域中,反映了活性中心的模块化组织。