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Impact of age-associated cyclopurine lesions on DNA repair helicases.

Title: Impact of age-associated cyclopurine lesions on DNA repair helicases.
Name(s): Khan, Irfan, author
Suhasini, Avvaru N, author
Banerjee, Taraswi, author
Sommers, Joshua A, author
Kaplan, Daniel L, author
Kuper, Jochen, author
Kisker, Caroline, author
Brosh, Robert M, author
Type of Resource: text
Genre: Journal Article
Date Issued: 2014-11-19
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: 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.
Identifier: FSU_pmch_25409515 (IID), 10.1371/journal.pone.0113293 (DOI), PMC4237422 (PMCID), 25409515 (RID), 25409515 (EID), PONE-D-14-42316 (PII)
Publication Note: This NIH-funded author manuscript originally appeared in PubMed Central at
Subject(s): Archaea/enzymology
Archaeal Proteins/isolation & purification
Archaeal Proteins/metabolism
DNA Damage
DNA Helicases/isolation & purification
DNA Helicases/metabolism
DNA Repair
Deoxyadenosines/chemical synthesis
Deoxyguanosine/chemical synthesis
Recombinant Proteins/isolation & purification
Recombinant Proteins/metabolism
Persistent Link to This Record:
Host Institution: FSU
Is Part Of: PloS one.
Issue: iss. 11, vol. 9

Choose the citation style.
Khan, I., Suhasini, A. N., Banerjee, T., Sommers, J. A., Kaplan, D. L., Kuper, J., … Brosh, R. M. (2014). Impact of age-associated cyclopurine lesions on DNA repair helicases. Plos One. Retrieved from