Nanomolar affinity of EF-hands in neuronal calcium sensor 1 for bivalent cations Pb2+, Mn2+, and Hg2.
Md Shofiul AlamSamiol AzamKhoa PhamDennys LeyvaKevin Jeanne Dit FouqueFrancisco Fernandez LimaJaroslava MiksovskaPublished in: Metallomics : integrated biometal science (2022)
Abiogenic metals Pb and Hg are highly toxic since chronic and/or acute exposure often leads to severe neuropathologies. Mn2+ is an essential metal ion but in excess can impair neuronal function. In this study, we address in vitro the interactions between neuronal calcium sensor 1 (NCS1) and divalent cations. Results showed that non-physiological ions (Pb2+ and Mn2+) bind to EF-hands in NCS1 with nanomolar affinity and lower equilibrium dissociation constant than the physiological Ca2+ ion. (Kd, Pb2+ = 7.0 ± 1.0 nM; Kd, Mn2+ = 34.0 ± 6.0 nM; K). Native ultra-high resolution mass spectrometry (FT-ICR MS) and trapped ion mobility spectrometry-mass spectrometry (nESI-TIMS-MS) studies provided the NCS1-metal complex compositions-up to four Ca2+ or Mn2+ ions and three Pb2+ ions (M⋅Pb1-3Ca1-3, M⋅Mn1-4Ca1-2, and M⋅Ca1-4) were observed in complex-and similarity across the mobility profiles suggests that the overall native structure is preserved regardless of the number and type of cations. However, the non-physiological metal ions (Pb2+, Mn2+, and Hg2+) binding to NCS1 leads to more efficient quenching of Trp emission and a decrease in W30 and W103 solvent exposure compared to the apo and Ca2+ bound form, although the secondary structural rearrangement and exposure of hydrophobic sites are analogous to those for Ca2+ bound protein. Only Pb2+ and Hg2+ binding to EF-hands leads to the NCS1 dimerization whereas Mn2+ bound NCS1 remains in the monomeric form, suggesting that other factors in addition to metal ion coordination, are required for protein dimerization.
Keyphrases
- aqueous solution
- mass spectrometry
- heavy metals
- room temperature
- transition metal
- metal organic framework
- ionic liquid
- liquid chromatography
- protein kinase
- high resolution mass spectrometry
- multiple sclerosis
- high resolution
- gas chromatography
- photodynamic therapy
- risk assessment
- binding protein
- respiratory failure
- intensive care unit
- fluorescent probe
- ultra high performance liquid chromatography
- drug induced
- early onset
- climate change
- simultaneous determination
- living cells
- brain injury
- quantum dots
- tandem mass spectrometry
- molecular dynamics
- case control