EVIDENCE SUPPORTING A TETHERED TRACKING MODEL FOR HELICASE ACTIVITY OF ESCHERICHIA-COLI RHO-FACTOR

被引:64
作者
STEINMETZ, EJ [1 ]
PLATT, T [1 ]
机构
[1] UNIV ROCHESTER,MED CTR,DEPT BIOCHEM,ROCHESTER,NY 14642
关键词
TRANSCRIPTION TERMINATION; TRANSLOCATION; ATPASE; RNA-PROTEIN INTERACTIONS; HEXAMERIC HELICASE;
D O I
10.1073/pnas.91.4.1401
中图分类号
O [数理科学和化学]; P [天文学、地球科学]; Q [生物科学]; N [自然科学总论];
学科分类号
07 ; 0710 ; 09 ;
摘要
Transcription termination factor Rho of Escherichia coli has an ATP-dependent RNA DNA helicase activity that presumably facilitates RNA transcript release from the elongation complex. This helicase activity is unidirectional (5' to 3') and is stoichiometric, with one RNA molecule released per Rho hexamer in vitro. A simple RNA tracking model postulates that after Rho's initial binding, it translocates preferentially toward the 3' end of the RNA. Nitrocellulose filter binding studies combined with RNase H cleavage are inconsistent with this simple tracking model. Instead, they support a model in which Rho forms tight primary binding interactions with the recognition region of the RNA and remains bound there while transient secondary RNA binding interactions coupled to ATP hydrolysis serve to scan along the RNA to contact the RNA DNA helix. This ''tethered tracking'' model is consistent with other properties of Rho factor, including the presence of two classes of RNA binding sites on the Rho hexamer and the 1:1 stoichiometry in the Rho helicase assay.
引用
收藏
页码:1401 / 1405
页数:5
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