title: Nuclear myosin I is necessary for the formation of the first phosphodiester bond during transcription initiation by RNA polymerase II.
abstract: The nuclear isoform of myosin, Nuclear Myosin I (NMI) is involved in transcription by RNA polymerase I. Previous experiments showing that antibodies to NMI inhibit transcription by RNA polymerase II using HeLa cell nuclear extract (NE) suggested that NMI might be a general transcription factor for RNA polymerases. In this study we used a minimal in vitro transcription system to investigate the involvement of NMI in transcription by RNA polymerase II in detail. We demonstrate that NMI co-purifies with RNA polymerase II and that NMI is necessary for basal transcription by RNA polymerase II because antibodies to NMI inhibit transcription while adding NMI stimulates transcription. Further investigation revealed that NMI is specifically involved in transcription initiation. Finally, by employing an abortive transcription initiation assay, we demonstrate that NMI is crucial for the formation of the first phosphodiester bond during transcription initiation.
authors.affiliation: Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA.
authors.forename: Wilma A
authors.initials: WA
authors.lastname: Hofmann
authors.forename: Gabriela M
authors.initials: GM
authors.lastname: Vargas
authors.forename: Ramaswamy
authors.initials: R
authors.lastname: Ramchandran
authors.forename: Ljuba
authors.initials: L
authors.lastname: Stojiljkovic
authors.forename: James A
authors.initials: JA
authors.lastname: Goodrich
authors.forename: Primal
authors.initials: P
authors.lastname: de Lanerolle
mesh_terms: D000818:Animals; D019556:COS Cells; D002467:Cell Nucleus / Q000378:metabolism*; D002522:Chlorocebus aethiops; D006367:HeLa Cells; D006801:Humans; D024461:Myosin Type I / Q000276:immunology / Q000302:isolation & purification / Q000378:metabolism*; D010710:Phosphates / Q000378:metabolism*; D011485:Protein Binding; D012319:RNA Polymerase II / Q000302:isolation & purification / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D010710:Phosphates; D012319:RNA Polymerase II; D024461:Myosin Type I