Transcription factor Rho does not require a free end to act as an RNA-DNA helicase on an RNA.
Escherichia coli Rho factor is a ring-shaped, homohexameric protein that terminates synthesis of RNA through interactions with the nascent RNA transcript. Because its mechanism of action may involve translocation of the RNA transcript through the hole in its ring structure, its action could depend on the availability of a free 5' terminus. To determine whether Rho's activity is 5'-end-dependent, its ability to bind to and function on a circular derivative of lambda cro mRNA was investigated. The circular derivative was made in vitro by action of RNA ligase on a derivative of lambda cro RNA containing an extra 10-nucleotide sequence near the 5'-end that was complementary to a sequence located near the 3'-end. Rho bound nearly as tightly to the circular derivative RNA as to the standard cro transcript. Rho was also able to readily dissociate a DNA oligonucleotide from its helical complex with the circular RNA in an ATP-dependent reaction. Thus, the action of Rho on a transcript does not depend on the availability of a free 5' terminus.
Burgess
B R
BR
Department of Chemistry, Indiana University, Bloomington, Indiana 47405, USA.
Richardson
J P
JP
D000255:Adenosine Triphosphate / Q000378:metabolism; D001483:Base Sequence; D001665:Binding Sites; D004265:DNA Helicases / Q000378:metabolism*; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000378:metabolism*; D007700:Kinetics; D009838:Oligodeoxyribonucleotides / Q000737:chemistry / Q000378:metabolism; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D020365:RNA Helicases / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D012097:Repressor Proteins / Q000235:genetics*; D012234:Rho Factor / Q000737:chemistry / Q000378:metabolism*; D013379:Substrate Specificity; D014157:Transcription Factors / Q000378:metabolism; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins
D004268:DNA-Binding Proteins; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D012097:Repressor Proteins; D012234:Rho Factor; D014157:Transcription Factors; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D012313:RNA; D000255:Adenosine Triphosphate; D004265:DNA Helicases; D020365:RNA Helicases