Characterization of a Novel Class I Transcription Factor A (CITFA) Subunit That Is Indispensable for Transcription by the Multifunctional RNA Polymerase I of Trypanosoma brucei
KAUST DepartmentBioscience Core Lab
MetadataShow full item record
AbstractTrypanosoma brucei is the only organism known to have evolved a multifunctional RNA polymerase I (pol I) system that is used to express the parasite's ribosomal RNAs, as well as its major cell surface antigens, namely, the variant surface glycoprotein (VSG) and procyclin, which are vital for establishing successful infections in the mammalian host and the tsetse vector, respectively. Thus far, biochemical analyses of the T. brucei RNA pol I transcription machinery have elucidated the subunit structure of the enzyme and identified the class I transcription factor A (CITFA). CITFA binds to RNA pol I promoters, and its CITFA-2 subunit was shown to be absolutely essential for RNA pol I transcription in the parasite. Tandem affinity purification (TAP) of CITFA revealed the subunits CITFA-1 to -6, which are conserved only among kinetoplastid organisms, plus the dynein light chain DYNLL1. Here, by tagging CITFA-6 instead of CITFA-2, a complex was purified that contained all known CITFA subunits, as well as a novel proline-rich protein. Functional studies carried out in vivo and in vitro, as well as a colocalization study, unequivocally demonstrated that this protein is a bona fide CITFA subunit, essential for parasite viability and indispensable for RNA pol I transcription of ribosomal gene units and the active VSG expression site in the mammalian-infective life cycle stage of the parasite. Interestingly, CITFA-7 function appears to be species specific, because expression of an RNA interference (RNAi)-resistant CITFA-7 transgene from Trypanosoma cruzi could not rescue the lethal phenotype of silencing endogenous CITFA-7.
CitationCharacterization of a Novel Class I Transcription Factor A (CITFA) Subunit That Is Indispensable for Transcription by the Multifunctional RNA Polymerase I of Trypanosoma brucei 2012, 11 (12):1573 Eukaryotic Cell
PublisherAmerican Society for Microbiology
PubMed Central IDPMC3536272
- Dynein Light Chain LC8 Is Required for RNA Polymerase I-Mediated Transcription in Trypanosoma brucei, Facilitating Assembly and Promoter Binding of Class I Transcription Factor A.
- Authors: Kirkham JK, Park SH, Nguyen TN, Lee JH, Günzl A
- Issue date: 2016 Jan 1
- Transcription by the multifunctional RNA polymerase I in Trypanosoma brucei functions independently of RPB7.
- Authors: Park SH, Nguyen TN, Kirkham JK, Lee JH, Günzl A
- Issue date: 2011 Nov
- Active RNA polymerase I of Trypanosoma brucei harbors a novel subunit essential for transcription.
- Authors: Nguyen TN, Schimanski B, Günzl A
- Issue date: 2007 Sep
- RNA polymerase I transcribes procyclin genes and variant surface glycoprotein gene expression sites in Trypanosoma brucei.
- Authors: Günzl A, Bruderer T, Laufer G, Schimanski B, Tu LC, Chung HM, Lee PT, Lee MG
- Issue date: 2003 Jun
- Metacyclic VSG expression site promoters are recognized by the same general transcription factor that is required for RNA polymerase I transcription of bloodstream expression sites.
- Authors: Kolev NG, Günzl A, Tschudi C
- Issue date: 2017 Sep