title: Aggregation of the neuroblastoma-associated mutant (S120G) of the human nucleoside diphosphate kinase-A/NM23-H1 into amyloid fibrils.
abstract: The human nucleoside diphosphate (NDP) kinase A, product of the NME1 gene also named NM23-H1, is known as a metastasis suppressor protein. A naturally occurring variant, S120G, identified in neuroblastomas, possesses native three-dimensional structure and enzymatic activity but displays reduced conformational stability and a folding defect with the accumulation of a "molten globule" folding intermediate during refolding in vitro. As such intermediate has been postulated to be involved in amyloid formation, NDP kinase A may serve as a model protein for studying the relationship between folding intermediates and amyloid fibrils. The NDP kinase A S120G was heated in phosphate buffer (pH 7.0). The protein precipitated as amyloid fibrils, as demonstrated by electron microscopy, Congo red, and thioflavin T binding and FTIR spectroscopy. The NDP kinase A S120G, at neutral pH and at moderate temperature experiences a transition towards amyloid fibrils. The aggregation process was faster if seeded by preformed fibrils. The fibrils presented a large proteinase K-resistant core not including residue Gly 120, as shown by mass spectrometry. This suggests that the aggregation process is triggered by the reduced stability of the S120G variant and not by a specific increase in the kinase domain intrinsic aggregation propensity at the place of mutation. This constitutes one of the few reports on a protein involved in cancer biology able to aggregate into amyloid structures under mild conditions.
authors.affiliation: Institut de Biochimie et Génétique Cellulaires, UMR 5095 University Bordeaux-2 and CNRS, 1 rue Camille St Saëns, 33077, Bordeaux cedex, France.
authors.forename: Florian
authors.initials: F
authors.lastname: Georgescauld
authors.forename: Raimon
authors.initials: R
authors.lastname: Sabaté
authors.forename: Alba
authors.initials: A
authors.lastname: Espargaró
authors.forename: Salvador
authors.initials: S
authors.lastname: Ventura
authors.forename: Stéphane
authors.initials: S
authors.lastname: Chaignepain
authors.forename: Marie-Lise
authors.initials: ML
authors.lastname: Lacombe
authors.forename: Ioan
authors.initials: I
authors.lastname: Lascu
mesh_terms: D000682:Amyloid / Q000737:chemistry* / Q000235:genetics*; D002942:Circular Dichroism; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D046529:Microscopy, Electron, Transmission; D009154:Mutation; D054778:NM23 Nucleoside Diphosphate Kinases / Q000737:chemistry* / Q000235:genetics*; D009447:Neuroblastoma / Q000235:genetics*; D011487:Protein Conformation; D017510:Protein Folding; D055550:Protein Stability; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013696:Temperature
chemical_list: D000682:Amyloid; D054778:NM23 Nucleoside Diphosphate Kinases; C517938:NME1 protein, human