title: Transcription termination factor La is also an initiation factor for RNA polymerase III.
abstract: La RNA-binding protein is a transcription termination factor that facilitates recycling of template and RNA polymerase (pol) 111. Transcription complexes preassembled on immobilized templates were depleted of pol III after a single round of RNA synthesis in the presence of heparin and sarkosyl. The isolated complexes could then be complemented with highly purified pol III and/or recombinant La to test if La is required for transcription reinitiation. VA1, 7SL, and B1 transcription complexes cannot be transcribed by supplemental pol III in single or multiple-round transcription assays unless La is also provided. La mediates concentration-dependent activation of pol III initiation and thereby controls the use of preassembled stable transcription complexes. The initiation factor activity of La augments its termination factor activity to produce a novel mechanism of activated reinitiation. A model in which La serves pol III upon transcription initiation and again at termination is discussed.
authors.affiliation: Laboratory of Molecular Growth Regulation, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892-2753, USA.
authors.forename: R J
authors.initials: RJ
authors.lastname: Maraia
mesh_terms: D001324:Autoantigens / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D066298:In Vitro Techniques; D008954:Models, Biological; D012313:RNA / Q000235:genetics / Q000378:metabolism; D012320:RNA Polymerase III / Q000378:metabolism*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D012261:Ribonucleoproteins / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D000097585:SS-B Antigen
chemical_list: D001324:Autoantigens; D012313:RNA; D012320:RNA Polymerase III; D011994:Recombinant Proteins; D012261:Ribonucleoproteins; D014157:Transcription Factors; D000097585:SS-B Antigen