TY  - JOUR
A1  - Schmitt, Dominik R.
A1  - Kuper, Jochen
A1  - Elias, Agnes
A1  - Kisker, Caroline
T1  - The Structure of the TFIIH p34 Subunit Reveals a Von Willebrand Factor A Like Fold
JF  - PLoS ONE
N2  - RNA polymerase II dependent transcription and nucleotide excision repair are mediated by a multifaceted interplay of subunits within the general transcription factor II H (TFIIH). A better understanding of the molecular structure of TFIIH is the key to unravel the mechanism of action of this versatile protein complex within these vital cellular processes. The importance of this complex becomes further evident in the context of severe diseases like xeroderma pigmentosum, Cockayne's syndrome and trichothiodystrophy, that arise from single point mutations in TFIIH subunits. Here we describe the structure of the p34 subunit of the TFIIH complex from the eukaryotic thermophilic fungus Chaetomium thermophilum. The structure revealed that p34 contains a von Willebrand Factor A (vWA) like domain, a fold which is generally known to be involved in protein-protein interactions. Within TFIIH p34 strongly interacts with p44, a positive regulator of the helicase XPD. Putative protein-protein interfaces are analyzed and possible binding sites for the p34-p44 interaction suggested.
KW  - sequence motif analysis
KW  - iodides
KW  - protein-protein interactions
KW  - protein domains
KW  - molecular structure
KW  - electron density
KW  - protein structure
KW  - crystal structure
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119471
SN  - 1932-6203
VL  - 9
IS  - 7
ER  - 
TY  - JOUR
A1  - Khan, Irfan
A1  - Suhasini, Avvaru N.
A1  - Banerjee, Taraswi
A1  - Sommers, Joshua A.
A1  - Kaplan, Daniel L.
A1  - Kuper, Jochen
A1  - Kisker, Caroline
A1  - Brosh, Jr., Robert M.
T1  - Impact of Age-Associated Cyclopurine Lesions on DNA Repair Helicases
JF  - PLOS ONE
N2  - 8,5' cyclopurine deoxynucleosides (cPu) are locally distorting DNA base lesions corrected by nucleotide excision repair (NER) and proposed to play a role in neurodegeneration prevalent in genetically defined Xeroderma pigmentosum (XP) patients. In the current study, purified recombinant helicases from different classifications based on sequence homology were examined for their ability to unwind partial duplex DNA substrates harboring a single site-specific cPu adduct. Superfamily (SF) 2 RecQ helicases (RECQ1, BLM, WRN, RecQ) were inhibited by cPu in the helicase translocating strand, whereas helicases from SF1 (UvrD) and SF4 (DnaB) tolerated cPu in either strand. SF2 Fe-S helicases (FANCJ, DDX11 (ChlR1), DinG, XPD) displayed marked differences in their ability to unwind the cPu DNA substrates. Archaeal Thermoplasma acidophilum XPD (taXPD), homologue to the human XPD helicase involved in NER DNA damage verification, was impeded by cPu in the non-translocating strand, while FANCJ was uniquely inhibited by the cPu in the translocating strand. Sequestration experiments demonstrated that FANCJ became trapped by the translocating strand cPu whereas RECQ1 was not, suggesting the two SF2 helicases interact with the cPu lesion by distinct mechanisms despite strand-specific inhibition for both. Using a protein trap to simulate single-turnover conditions, the rate of FANCJ or RECQ1 helicase activity was reduced 10-fold and 4.5-fold, respectively, by cPu in the translocating strand. In contrast, single-turnover rates of DNA unwinding by DDX11 and UvrD helicases were only modestly affected by the cPu lesion in the translocating strand. The marked difference in effect of the translocating strand cPu on rate of DNA unwinding between DDX11 and FANCJ helicase suggests the two Fe-S cluster helicases unwind damaged DNA by distinct mechanisms. The apparent complexity of helicase encounters with an unusual form of oxidative damage is likely to have important consequences in the cellular response to DNA damage and DNA repair.
KW  - nucleotide excision-repair
KW  - replication fork
KW  - substrate specificity
KW  - translesion synthesis
KW  - genomic stability
KW  - Warsaw breakage syndrome
KW  - escherichia coli
KW  - xeroderma-pigmentosum
KW  - human cells
KW  - biochemical characterization
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-114635
VL  - 9
IS  - 11
ER  -