title: Direct Characterization of Transcription Elongation by RNA Polymerase I.
abstract: RNA polymerase I (Pol I) transcribes ribosomal DNA and is responsible for more than 60% of transcription in a growing cell. Despite this fundamental role that directly impacts cell growth and proliferation, the kinetics of transcription by Pol I are poorly understood. This study provides direct characterization of S. Cerevisiae Pol I transcription elongation using tethered particle microscopy (TPM). Pol I was shown to elongate at an average rate of approximately 20 nt/s. However, the maximum speed observed was, in average, about 60 nt/s, comparable to the rate calculated based on the in vivo number of active genes, the cell division rate and the number of engaged polymerases observed in EM images. Addition of RNA endonucleases to the TPM elongation assays enhanced processivity. Together, these data suggest that additional transcription factors contribute to efficient and processive transcription elongation by RNA polymerase I in vivo.
authors.affiliation: Physics Department, Emory University, Atlanta, GA, 30322, United States of America.
authors.forename: Suleyman
authors.initials: S
authors.lastname: Ucuncuoglu
authors.affiliation: Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.
authors.forename: Krysta L
authors.initials: KL
authors.lastname: Engel
authors.affiliation: Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, PA, 19104, United States of America.
authors.forename: Prashant K
authors.initials: PK
authors.lastname: Purohit
authors.affiliation: Physics Department, Emory University, Atlanta, GA, 30322, United States of America.
authors.forename: David D
authors.initials: DD
authors.lastname: Dunlap
authors.affiliation: Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, AL, 35294, United States of America.
authors.forename: David A
authors.initials: DA
authors.lastname: Schneider
authors.affiliation: Physics Department, Emory University, Atlanta, GA, 30322, United States of America.
authors.forename: Laura
authors.identifier: http://orcid.org/0000-0003-1173-5339
authors.initials: L
authors.lastname: Finzi
mesh_terms: D005786:Gene Expression Regulation; D007700:Kinetics; D008853:Microscopy / Q000379:methods; D057054:Molecular Imaging; D034622:RNA Interference; D012318:RNA Polymerase I / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D061805:Transcription Elongation, Genetic; D014158:Transcription, Genetic
chemical_list: D012318:RNA Polymerase I