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T rypanosoma brucei harbours a divergent XPB helicase paralogue that is specialized in nucleotide excision repair and conserved among kinetoplastid organisms
Author(s) -
Badjatia Nitika,
Nguyen Tu N.,
Lee Ju Huck,
Günzl Arthur
Publication year - 2013
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12435
Subject(s) - transcription factor ii h , biology , nucleotide excision repair , helicase , transcription (linguistics) , rna polymerase ii , dna repair , genetics , microbiology and biotechnology , rna polymerase , gene , rna , gene expression , promoter , linguistics , philosophy
Summary 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 X eroderma pigmentosum B ( XPB ) and a kinase subcomplex. T rypanosoma 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 K inetoplastida.