1. Trypanosoma brucei harbours a divergent XPB helicase paralogue that is specialized in nucleotide excision repair and conserved among kinetoplastid organisms.
- Author
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Badjatia, Nitika, Nguyen, Tu N., Lee, Ju Huck, and Günzl, Arthur
- Subjects
TRYPANOSOMA brucei ,HARBORS ,XERODERMA pigmentosum ,DNA repair ,DNA helicases ,RNA polymerases ,KINETOPLASTIDA - Abstract
Conserved from yeast to humans, TFIIH is essential for RNA polymerase II transcription and nucleotide excision repair ( NER). TFIIH consists of a core that includes the DNA helicase Xeroderma pigmentosum B ( XPB) and a kinase subcomplex. Trypanosoma brucei TFIIH harbours all core complex components and is indispensable for RNA polymerase II transcription of spliced leader RNA genes ( SLRNAs). Kinetoplastid organisms, however, possess two highly divergent XPB paralogues with only the larger being identified as a TFIIH subunit in T. brucei. Here we show that a knockout of the gene for the smaller paralogue, termed XPB-R ( R for repair) resulted in viable cultured trypanosomes that grew slower than normal. XPB- R depletion did not affect transcription in vivo or in vitro and XPB-R was not found to occupy the SLRNA promoter which assembles a RNA polymerase II transcription pre-initiation complex including TFIIH. However, XPB-R
−/− cells were much less tolerant than wild-type cells to UV light- and cisplatin-induced DNA damage, which require NER. Since XPB-R−/− cells were not impaired in DNA base excision repair, XPB- R appears to function specifically in NER. Interestingly, several other protists possess highly divergent XPB paralogues suggesting that XPBs specialized in transcription or NER exist beyond the Kinetoplastida. [ABSTRACT FROM AUTHOR]- Published
- 2013
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