title: Base J represses genes at the end of polycistronic gene clusters in Leishmania major by promoting RNAP II termination.
abstract: The genomes of kinetoplastids are organized into polycistronic gene clusters that are flanked by the modified DNA base J. Previous work has established a role of base J in promoting RNA polymerase II termination in Leishmania spp. where the loss of J leads to termination defects and transcription into adjacent gene clusters. It remains unclear whether these termination defects affect gene expression and whether read through transcription is detrimental to cell growth, thus explaining the essential nature of J. We now demonstrate that reduction of base J at specific sites within polycistronic gene clusters in L. major leads to read through transcription and increased expression of downstream genes in the cluster. Interestingly, subsequent transcription into the opposing polycistronic gene cluster does not lead to downregulation of sense mRNAs. These findings indicate a conserved role for J regulating transcription termination and expression of genes within polycistronic gene clusters in trypanosomatids. In contrast to the expectations often attributed to opposing transcription, the essential nature of J in Leishmania spp. is related to its role in gene repression rather than preventing transcriptional interference resulting from read through and dual strand transcription.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, 30602, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Reynolds
authors.affiliation: Institute of Bioinformatics, University of Georgia, Athens, Georgia, 30602, USA.
authors.forename: Brigitte T
authors.initials: BT
authors.lastname: Hofmeister
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, 30602, USA.
authors.forename: Laura
authors.initials: L
authors.lastname: Cliffe
authors.affiliation: Research Center for Infectious Diseases, University of Wuerzburg, Wuerzburg, 97080, Germany.
authors.forename: T Nicolai
authors.initials: TN
authors.lastname: Siegel
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
authors.forename: Britta A
authors.initials: BA
authors.lastname: Anderson
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
authors.forename: Stephen M
authors.initials: SM
authors.lastname: Beverley
authors.affiliation: Department of Genetics, University of Georgia, Athens, Georgia, 30602, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Schmitz
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, 30602, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: Sabatini
mesh_terms: D005786:Gene Expression Regulation; D005960:Glucosides / Q000235:genetics* / Q000378:metabolism; D018320:Leishmania major / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000235:genetics; D014498:Uracil / Q000031:analogs & derivatives* / Q000378:metabolism
chemical_list: D005960:Glucosides; D012333:RNA, Messenger; C084880:5-((glucopyranosyloxy)methyl)uracil; D014498:Uracil; D012319:RNA Polymerase II