title: Structural basis of lariat RNA recognition by the intron debranching enzyme Dbr1.
abstract: The enzymatic processing of cellular RNA molecules requires selective recognition of unique chemical and topological features. The unusual 2',5'-phosphodiester linkages in RNA lariats produced by the spliceosome must be hydrolyzed by the intron debranching enzyme (Dbr1) before they can be metabolized or processed into essential cellular factors, such as snoRNA and miRNA. Dbr1 is also involved in the propagation of retrotransposons and retroviruses, although the precise role played by the enzyme in these processes is poorly understood. Here, we report the first structures of Dbr1 alone and in complex with several synthetic RNA compounds that mimic the branchpoint in lariat RNA. The structures, together with functional data on Dbr1 variants, reveal the molecular basis for 2',5'-phosphodiester recognition and explain why the enzyme lacks activity toward 3',5'-phosphodiester linkages. The findings illuminate structure/function relationships in a unique enzyme that is central to eukaryotic RNA metabolism and set the stage for the rational design of inhibitors that may represent novel therapeutic agents to treat retroviral infections and neurodegenerative disease.
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center, San Antonio, TX 78229, USA X-ray Crystallography Core Laboratory, The University of Texas Health Science Center, San Antonio, TX 78229, USA.
authors.forename: Eric J
authors.initials: EJ
authors.lastname: Montemayor
authors.affiliation: Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada.
authors.forename: Adam
authors.initials: A
authors.lastname: Katolik
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center, San Antonio, TX 78229, USA X-ray Crystallography Core Laboratory, The University of Texas Health Science Center, San Antonio, TX 78229, USA.
authors.forename: Nathaniel E
authors.initials: NE
authors.lastname: Clark
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center, San Antonio, TX 78229, USA X-ray Crystallography Core Laboratory, The University of Texas Health Science Center, San Antonio, TX 78229, USA.
authors.forename: Alexander B
authors.initials: AB
authors.lastname: Taylor
authors.affiliation: Northeastern Collaborative Access Team, Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY 14853, USA.
authors.forename: Jonathan P
authors.initials: JP
authors.lastname: Schuermann
authors.affiliation: Program in Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78212, USA.
authors.forename: D Joshua
authors.initials: DJ
authors.lastname: Combs
authors.affiliation: Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada.
authors.forename: Richard
authors.initials: R
authors.lastname: Johnsson
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center, San Antonio, TX 78229, USA.
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Holloway
authors.affiliation: Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA scott.stevens@austin.utexas.edu.
authors.forename: Scott W
authors.initials: SW
authors.lastname: Stevens
authors.affiliation: Department of Chemistry, McGill University, Montreal, Quebec H3A 0B8, Canada masad.damha@mcgill.ca.
authors.forename: Masad J
authors.initials: MJ
authors.lastname: Damha
authors.affiliation: Department of Biochemistry, The University of Texas Health Science Center, San Antonio, TX 78229, USA X-ray Crystallography Core Laboratory, The University of Texas Health Science Center, San Antonio, TX 78229, USA Geriatric Research, Education, and Clinical Center, Department of Veterans Affairs, South Texas Veterans Health Care System, San Antonio, TX 78229, USA pjhart1@biochem.uthscsa.edu.
authors.forename: P John
authors.identifier: http://orcid.org/0000-0003-1097-3992
authors.initials: PJ
authors.lastname: Hart
mesh_terms: D004748:Entamoeba histolytica / Q000201:enzymology; D007438:Introns; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D017434:Protein Structure, Tertiary; D012313:RNA / Q000737:chemistry / Q000378:metabolism; D012316:RNA Nucleotidyltransferases / Q000737:chemistry* / Q000378:metabolism
chemical_list: D012313:RNA; D012316:RNA Nucleotidyltransferases