title: Structure-function analysis of RNA polymerases I and III.
abstract: Recent advances in elucidating the structure of yeast Pol I and III are based on a combination of X-ray crystal analysis, electron microscopy and homology modelling. They allow a better comparison of the three eukaryotic nuclear RNA polymerases, underscoring the most obvious difference existing between the three enzymes, which lies in the existence of additional Pol-I-specific and Pol-III-specific subunits. Their location on the cognate RNA polymerases is now fairly well known, suggesting precise hypotheses as to their function in transcription during initiation, elongation, termination and/or reinitiation. Unexpectedly, even though Pol I and III, but not Pol II, have an intrinsic RNA cleavage activity, it was found that TFIIS Pol II cleavage stimulation factor also played a general role in Pol III transcription.
authors.affiliation: CEA, iRCM, F-91057 Evry Cedex, France. michel.werner@cea.fr
authors.forename: Michel
authors.initials: M
authors.lastname: Werner
authors.forename: Pierre
authors.initials: P
authors.lastname: Thuriaux
authors.forename: Julie
authors.initials: J
authors.lastname: Soutourina
mesh_terms: D000818:Animals; D006801:Humans; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D012318:RNA Polymerase I / Q000737:chemistry* / Q000378:metabolism*; D012320:RNA Polymerase III / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic; D035602:Transcriptional Elongation Factors / Q000378:metabolism
chemical_list: D021122:Protein Subunits; D035602:Transcriptional Elongation Factors; C018648:transcription factor S-II; D012318:RNA Polymerase I; D012320:RNA Polymerase III