Mustaev A, Kashlev M, Zaychikov E, Grachev M, Goldfarb A
Public Health Research Institute, New York, New York 10016.
J Biol Chem. 1993 Sep 15;268(26):19185-7.
His1237 in the beta subunit of Escherichia coli RNA polymerase marks the "5' face" of the active center since it can be cross-linked to the gamma-phosphate of the priming substrate. It is demonstrated that RNA chains up to 9 nucleotides in length can be synthesized using His1237-cross-linked nucleotide as a primer. Thus, a substantial mass of RNA can be accommodated in the active center between His1237 and the site of catalysis that remains juxtaposed to the growing 3' end. The apparent "filling" of the active center with RNA precedes promoter clearance and suggests a mechanism of coupling between catalysis and saltatory translocation of RNA polymerase.
大肠杆菌RNA聚合酶β亚基中的His1237标记了活性中心的“5'面”，因为它可以与引发底物的γ-磷酸基团交联。结果表明，以His1237交联的核苷酸为引物，可以合成长度达9个核苷酸的RNA链。因此，在His1237和与正在生长的3'端并列的催化位点之间的活性中心可以容纳大量的RNA。活性中心明显被RNA“填满”发生在启动子清除之前，这提示了一种RNA聚合酶催化作用与跳跃式易位之间的偶联机制。
