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Neurodegenerative disease-associated mutants of a human mitochondrial aminoacyl-tRNA synthetase present individual molecular signatures.

Sauter C, Lorber B, Gaudry A, Karim L, Schwenzer H, Wien F, Roblin P, Florentz C, Sissler M - Sci Rep (2015)

Bottom Line: The effects of these mutations on the structure and function of the enzymes remain to be established.Mutations with mild effects on solubility occur in patients as allelic combinations whereas those with strong effects on solubility or on aminoacylation are necessarily associated with a partially functional allele.The fact that all mutations show individual molecular and cellular signatures and affect amino acids only conserved in mammals, points towards an alternative function besides aminoacylation.

View Article: PubMed Central - PubMed

Affiliation: Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, IBMC, 15 rue René Descartes, 67084 STRASBOURG Cedex, France.

ABSTRACT
Mutations in human mitochondrial aminoacyl-tRNA synthetases are associated with a variety of neurodegenerative disorders. The effects of these mutations on the structure and function of the enzymes remain to be established. Here, we investigate six mutants of the aspartyl-tRNA synthetase correlated with leukoencephalopathies. Our integrated strategy, combining an ensemble of biochemical and biophysical approaches, reveals that mutants are diversely affected with respect to their solubility in cellular extracts and stability in solution, but not in architecture. Mutations with mild effects on solubility occur in patients as allelic combinations whereas those with strong effects on solubility or on aminoacylation are necessarily associated with a partially functional allele. The fact that all mutations show individual molecular and cellular signatures and affect amino acids only conserved in mammals, points towards an alternative function besides aminoacylation.

No MeSH data available.


Related in: MedlinePlus

Differential thermal stability of WT mt-AspRS and mutants.(A) Temperature-dependent binding of a fluorescent hydrophobic dye measured by DSF, in the absence and in the presence of an aminoacyl-adenylate analog 5′-O-[N-(L-aspartyl)sulfamoyl]adenosine (Asp-AMS). (B) Thermal stability of structural secondary elements. (Left) Temperature dependent variation of the molar ellipticity at 209 nm measured by SRCD. (Right) Derivatives of sigmoidal fits of curves displayed in the left panel with maxima corresponding to the Tm. Color code is as in Fig. 1.
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f3: Differential thermal stability of WT mt-AspRS and mutants.(A) Temperature-dependent binding of a fluorescent hydrophobic dye measured by DSF, in the absence and in the presence of an aminoacyl-adenylate analog 5′-O-[N-(L-aspartyl)sulfamoyl]adenosine (Asp-AMS). (B) Thermal stability of structural secondary elements. (Left) Temperature dependent variation of the molar ellipticity at 209 nm measured by SRCD. (Right) Derivatives of sigmoidal fits of curves displayed in the left panel with maxima corresponding to the Tm. Color code is as in Fig. 1.

Mentions: In DSF experiment, the transition mid-point temperatures derived from increase of fluorescence intensity of R263Q, L613F, and L626Q were comparable to that of WT mt-AspRS (Tm = 47 to 48 ± 1 °C) (Fig. 3A). The Tm of Q184K was lower by ~2 °C and those of R58G and T136S lower by as much as 3 °C. In the presence of Asp-AMS, the Tm values of WT and R58G were 54 ± 1 °C and 53 ± 1 °C, respectively. Those of T136S, L613F, and L626Q were 52 ± 1 °C. The stabilizing effect of Asp-AMS on WT mt-AspRS26 was also strong on R58G and T136S (ΔTm = +7 to +8 °C), but lower on L613F and L626Q (ΔTm = +4 to +5 °C), very low on Q184K (ΔTm = +2 °C), and negligible on R263Q (ΔTm = 0 °C) (Fig. 3A).


Neurodegenerative disease-associated mutants of a human mitochondrial aminoacyl-tRNA synthetase present individual molecular signatures.

Sauter C, Lorber B, Gaudry A, Karim L, Schwenzer H, Wien F, Roblin P, Florentz C, Sissler M - Sci Rep (2015)

Differential thermal stability of WT mt-AspRS and mutants.(A) Temperature-dependent binding of a fluorescent hydrophobic dye measured by DSF, in the absence and in the presence of an aminoacyl-adenylate analog 5′-O-[N-(L-aspartyl)sulfamoyl]adenosine (Asp-AMS). (B) Thermal stability of structural secondary elements. (Left) Temperature dependent variation of the molar ellipticity at 209 nm measured by SRCD. (Right) Derivatives of sigmoidal fits of curves displayed in the left panel with maxima corresponding to the Tm. Color code is as in Fig. 1.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664897&req=5

f3: Differential thermal stability of WT mt-AspRS and mutants.(A) Temperature-dependent binding of a fluorescent hydrophobic dye measured by DSF, in the absence and in the presence of an aminoacyl-adenylate analog 5′-O-[N-(L-aspartyl)sulfamoyl]adenosine (Asp-AMS). (B) Thermal stability of structural secondary elements. (Left) Temperature dependent variation of the molar ellipticity at 209 nm measured by SRCD. (Right) Derivatives of sigmoidal fits of curves displayed in the left panel with maxima corresponding to the Tm. Color code is as in Fig. 1.
Mentions: In DSF experiment, the transition mid-point temperatures derived from increase of fluorescence intensity of R263Q, L613F, and L626Q were comparable to that of WT mt-AspRS (Tm = 47 to 48 ± 1 °C) (Fig. 3A). The Tm of Q184K was lower by ~2 °C and those of R58G and T136S lower by as much as 3 °C. In the presence of Asp-AMS, the Tm values of WT and R58G were 54 ± 1 °C and 53 ± 1 °C, respectively. Those of T136S, L613F, and L626Q were 52 ± 1 °C. The stabilizing effect of Asp-AMS on WT mt-AspRS26 was also strong on R58G and T136S (ΔTm = +7 to +8 °C), but lower on L613F and L626Q (ΔTm = +4 to +5 °C), very low on Q184K (ΔTm = +2 °C), and negligible on R263Q (ΔTm = 0 °C) (Fig. 3A).

Bottom Line: The effects of these mutations on the structure and function of the enzymes remain to be established.Mutations with mild effects on solubility occur in patients as allelic combinations whereas those with strong effects on solubility or on aminoacylation are necessarily associated with a partially functional allele.The fact that all mutations show individual molecular and cellular signatures and affect amino acids only conserved in mammals, points towards an alternative function besides aminoacylation.

View Article: PubMed Central - PubMed

Affiliation: Architecture et Réactivité de l'ARN, CNRS, Université de Strasbourg, IBMC, 15 rue René Descartes, 67084 STRASBOURG Cedex, France.

ABSTRACT
Mutations in human mitochondrial aminoacyl-tRNA synthetases are associated with a variety of neurodegenerative disorders. The effects of these mutations on the structure and function of the enzymes remain to be established. Here, we investigate six mutants of the aspartyl-tRNA synthetase correlated with leukoencephalopathies. Our integrated strategy, combining an ensemble of biochemical and biophysical approaches, reveals that mutants are diversely affected with respect to their solubility in cellular extracts and stability in solution, but not in architecture. Mutations with mild effects on solubility occur in patients as allelic combinations whereas those with strong effects on solubility or on aminoacylation are necessarily associated with a partially functional allele. The fact that all mutations show individual molecular and cellular signatures and affect amino acids only conserved in mammals, points towards an alternative function besides aminoacylation.

No MeSH data available.


Related in: MedlinePlus