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Publication Abstract from PubMed

Human NAD(P)H:quinone oxidoreductase (NQO1) is essential for the antioxidant defence system, stabilization of tumour suppressors (e.g. p53, p33 and p73) and activation of quinone based chemotherapeutics. Overexpression of NQO1 in many solid tumours coupled with its ability to convert quinone-based chemotherapeutics into potent cytotoxic compounds made it a very attractive target for anti-cancer drugs. A naturally occurring single nucleotide polymorphism (transition from C609T) leading to an amino acid exchange (P187S) has been implicated in development of various cancers and poor survival rates following anthracyclin based adjuvant chemotherapy. Despite the importance for cancer prediction and therapy, the exact molecular basis for the loss of function in NQO1 P187S is currently unknown. Therefore we solved the crystal structure of NQO1 P187S. Surprisingly, this structure is virtually identical to NQO1. Employing a combination of NMR spectroscopy and limited proteolysis experiments we demonstrate that the single amino acid exchange destabilizes interactions between the core and C-terminal domain leading to depopulation of the native structure in solution. This collapse of the native structure diminishes cofactor affinity and leads to a less competent FAD binding pocket thus severely compromising the catalytic capacity of the variant protein. Hence our findings provide a rationale for the loss of function in NQO1 P187S due to a frequently occurring single nucleotide polymorphism. This article is protected by copyright. All rights reserved. STRUCTURED DIGITAL ABSTRACT: NQO1 P187S and NQO1 P187S bind by nuclear magnetic resonance (View interaction) NQO1 P187S and NQO1 P187S bind by x-ray crystallography (1, 2) NQO1 and NQO1 bind by molecular sieving (1, 2).

Collapse of the native structure by a single amino acid exchange in human NAD(P)H:quinone oxidoreductase (NQO1).,Lienhart WD, Gudipati V, Uhl MK, Binter A, Pulido S, Saf R, Zangger K, Gruber K, Macheroux P FEBS J. 2014 Aug 20. doi: 10.1111/febs.12975. PMID:25143260^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.