Borukhov S, Polyakov A, Nikiforov V, Goldfarb A
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, NY 10032.
Proc Natl Acad Sci U S A. 1992 Oct 1;89(19):8899-902. doi: 10.1073/pnas.89.19.8899.
A protein identified as the 158-amino acid product of the greA gene was isolated from Escherichia coli. When added to a halted ternary transcription complex, the GreA protein induced cleavage and removal of the 3' proximal dinucleotide from the nascent RNA. The new 3' terminus generated by the cleavage could be extended into longer transcripts. GreA-mediated cleavage of a transcript appears to permit a ternary complex to resume transcription from a state of indefinite elongation arrest induced by a specific DNA site. The GreA protein tended to interact with RNA polymerase during purification and recycled between RNA polymerase molecules in the course of the in vitro cleavage reaction. Similar biochemical activities have been reported in eukaryotic RNA polymerases, indicating that transcript cleavage and restart of elongation may be a general transcriptional mechanism.
从大肠杆菌中分离出一种被鉴定为greA基因158个氨基酸产物的蛋白质。当将其添加到停滞的三元转录复合物中时，GreA蛋白可诱导从新生RNA上切割并去除3'近端二核苷酸。切割产生的新3'末端可延伸为更长的转录本。GreA介导的转录本切割似乎能使三元复合物从由特定DNA位点诱导的无限延伸停滞状态恢复转录。在纯化过程中，GreA蛋白倾向于与RNA聚合酶相互作用，并在体外切割反应过程中在RNA聚合酶分子之间循环。真核RNA聚合酶中也报道了类似的生化活性，这表明转录本切割和延伸重新启动可能是一种普遍的转录机制。
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