TbENF is an essential TbTFIIB-interacting trypanosomatid-specific factor

Abstract

Trypanosoma brucei, the causative agent of African Sleeping sickness, is replete with unique biochemistry, including unusual features of gene transcription. The parasite also contains over 4500 non-annotated genes, representing novel biochemistry yet to be explored. Using tandem affinity purification (TAP)-tagged TbTFIIB, we identified and subsequently confirmed, one of the non-annotated Trypanosoma brucei proteins, Tb11.02.4300, as a TbTFIIB-interacting protein. The 49 kDa protein is nuclear and essential for parasite variability as determined by RNA interference studies; hence, the nomenclature T. brucei Essential Nuclear Factor (TbENF). TbENF is shown to interact with DNA in a sequence-independent fashion under the conditions examined. Furthermore, TbENF bears motifs associated with many eukaryotic transcription factors, such as a glutamine-rich region and a leucine zipper, yet TbENF is specific to trypanosomatids making it a potentially attractive therapeutic target. Taken together, our results suggest a role for TbENF in trypanosome gene transcription.

Depletion of Trypanosome CTR9 Leads to Gene Expression Defects

“…Some examples of essential genes with at least 20-fold RNA decreases are shown in Table 4 . Multiple genes that encode proteins involved in gene expression now had less than one copy of mRNA per cell: the largest RNA polymerase II subunit and the second largest polymerase I subunit; the TFIIB-interacting protein ENF [34] ; two components of the mRNA degradation machinery, NOT1 and XRNA; poly(A) binding protein 2 and some translation factors. There were also other targets potentially involved in gene expression: 7 RNA helicases, including DHH1; zinc finger proteins ZC3H22, ZC3H28, ZC3H32, and ZC3H41, RNA-binding domain proteins DRBD12 and DRBD17, and nearly all of the pumilio domain proteins.…”

“…Some are identifiable (although often extremely diverged) homologues of known transcription factors from other eukaryotes, but others are not. For example, the spliced leader promoter-binding complex has a Kinetoplastid-specific subunit [33] ; ENF, a protein that interacts with TfIIB, has various motifs that are found in transcription factors, but has no clear Opisthokont homologue [34] ; and the trypanosome Mediator complex resembles that of yeast in overall shape (as judged by electron microscopy) but not in the protein primary structures [35] , [36] .…”