Martin T Hess

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The fjord region diol-epoxide metabolites of polycyclic aromatic hydrocarbons display stronger tumorigenic activities in rodent studies than comparable bay region diol-epoxides, but the molecular basis for this difference between fjord and bay region derivatives is not understood. Here we tested whether the variable effects of these genotoxic metabolites of(More)
Human nucleotide excision repair processes carcinogen-DNA adducts at highly variable rates, even at adjacent sites along individual genes. Here, we identify conformational determinants of fast or slow repair by testing excision of N2-guanine adducts formed by benzo[a]pyrene diol epoxide (BPDE), a potent and ubiquitous mutagen that induces mainly G x C-->T x(More)
Indirect evidence has suggested that the Msh2-Msh6 mispair-binding complex undergoes conformational changes upon binding of ATP and mispairs, resulting in the formation of Msh2-Msh6 sliding clamps and licensing the formation of Msh2-Msh6-Mlh1-Pms1 ternary complexes. Here, we have studied eight mutant Msh2-Msh6 complexes with defective responses to(More)
Here, the ATP-binding, ATP hydrolysis, mispair-binding, sliding clamp formation, and Mlh1-Pms1 complex interaction properties of dominant mutant Msh2-Msh6 complexes have been characterized. The results demonstrate two mechanisms for dominance. In one, seen with the Msh6-S1036P and Msh6-G1067D mutant complexes, the mutant complex binds mispaired bases, is(More)
Mammalian nucleotide excision repair (NER) eliminates carcinogen-DNA adducts by double endonucleolytic cleavage and subsequent release of 24-32 nucleotide-long single-stranded fragments. Here we manipulated the deoxyribose-phosphate backbone of DNA to analyze the mechanism by which damaged strands are discriminated as substrates for dual incision. We found(More)
A previous study described four dominant msh6 mutations that interfere with both the Msh2-Msh6 and Msh2-Msh3 mismatch recognition complexes (Das Gupta, R., and Kolodner, R. D. (2000) Nat. Genet. 24, 53-56). Modeling predicted that two of the amino acid substitutions (G1067D and G1142D) interfere with protein-protein interactions at the ATP-binding(More)
BACKGROUND & AIMS Recent evidence suggests that patients with advanced microsatellite unstable (MSI) colorectal cancers lack a survival benefit with 5-fluorouracil (5-FU)-based chemotherapy. Additionally, tumor cells with MSI (caused by defective DNA mismatch repair) are more resistant to 5-FU in culture compared with microsatellite stable cells, despite(More)
Nondistorting C4' backbone adducts serve as molecular tools to analyze the strategy by which a limited number of human nucleotide excision repair (NER) factors recognize an infinite variety of DNA lesions. We have constructed composite DNA substrates containing a noncomplementary site adjacent to a nondistorting C4' adduct to show that the loss of hydrogen(More)
The mechanism by which mammalian nucleotide excision repair (NER) detects a wide range of base lesions is poorly understood. Here, we tested the ability of human NER to recognize bulky modifications that either destabilize the DNA double helix (acetylaminofluorene (AAF) and benzo[a]pyrene diol-epoxide (BPDE) adducts, UV radiation products) or induce(More)
To assess helical parameters that dictate fast or slow removal of carcinogen-DNA adducts, we probed human nucleotide excision repair (NER) activity with DNA containing L-deoxyriboses. Unlike natural lesions such as pyrimidine dimers or base adducts, L-deoxyribonucleosides (the mirror images of normal D-deoxyribonucleosides) involve neither the addition nor(More)