title: Functional architecture of the Reb1-Ter complex of Schizosaccharomyces pombe.
abstract: Reb1 ofSchizosaccharomyces pomberepresents a family of multifunctional proteins that bind to specific terminator sites (Ter) and cause polar termination of transcription catalyzed by RNA polymerase I (pol I) and arrest of replication forks approaching the Ter sites from the opposite direction. However, it remains to be investigated whether the same mechanism causes arrest of both DNA transactions. Here, we present the structure of Reb1 as a complex with a Ter site at a resolution of 2.7 Å. Structure-guided molecular genetic analyses revealed that it has distinct and well-defined DNA binding and transcription termination (TTD) domains. The region of the protein involved in replication termination is distinct from the TTD. Mechanistically, the data support the conclusion that transcription termination is not caused by just high affinity Reb1-Ter protein-DNA interactions. Rather, protein-protein interactions between the TTD with the Rpa12 subunit of RNA pol I seem to be an integral part of the mechanism. This conclusion is further supported by the observation that double mutations in TTD that abolished its interaction with Rpa12 also greatly reduced transcription termination thereby revealing a conduit for functional communications between RNA pol I and the terminator protein.
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298;
authors.forename: Rahul
authors.initials: R
authors.lastname: Jaiswal
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425.
authors.forename: Malay
authors.initials: M
authors.lastname: Choudhury
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425.
authors.forename: Shamsu
authors.initials: S
authors.lastname: Zaman
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425.
authors.forename: Samarendra
authors.initials: S
authors.lastname: Singh
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298;
authors.forename: Vishaka
authors.initials: V
authors.lastname: Santosh
authors.affiliation: Department of Biochemistry and Molecular Biology, Medical University of South Carolina, Charleston, SC 29425 bastia@musc.edu crescalante@vcuhealth.org.
authors.forename: Deepak
authors.initials: D
authors.lastname: Bastia
authors.affiliation: Department of Physiology and Biophysics, Virginia Commonwealth University, Richmond, VA 23298; bastia@musc.edu crescalante@vcuhealth.org.
authors.forename: Carlos R
authors.initials: CR
authors.lastname: Escalante
mesh_terms: D018360:Crystallography, X-Ray; D004271:DNA, Fungal / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012318:RNA Polymerase I / Q000737:chemistry / Q000378:metabolism; D012568:Schizosaccharomyces / Q000737:chemistry* / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry* / Q000378:metabolism; D013728:Terminator Regions, Genetic; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism; D061806:Transcription Termination, Genetic
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; D014157:Transcription Factors; C512907:reb1 protein, S pombe; D012318:RNA Polymerase I
keywords: RNA polymerase I; crystal structure; protein–DNA interaction; replication termination; transcription termination