Loss of function in phenylketonuria is caused by impaired molecular motions and conformational instability
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Loss of function in phenylketonuria is caused by impaired molecular motions and conformational instability. / Gersting, Søren W; Kemter, Kristina F; Staudigl, Michael; Messing, Dunja D; Danecka, Marta K; Lagler, Florian B; Sommerhoff, Christian P; Roscher, Adelbert A; Muntau, Ania C.
In: AM J HUM GENET, Vol. 83, No. 1, 07.2008, p. 5-17.Research output: SCORING: Contribution to journal › SCORING: Journal article › Research › peer-review
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T1 - Loss of function in phenylketonuria is caused by impaired molecular motions and conformational instability
AU - Gersting, Søren W
AU - Kemter, Kristina F
AU - Staudigl, Michael
AU - Messing, Dunja D
AU - Danecka, Marta K
AU - Lagler, Florian B
AU - Sommerhoff, Christian P
AU - Roscher, Adelbert A
AU - Muntau, Ania C
PY - 2008/7
Y1 - 2008/7
N2 - A significant share of patients with phenylalanine hydroxylase (PAH) deficiency benefits from pharmacological doses of tetrahydrobiopterin (BH(4)), the natural PAH cofactor. Phenylketonuria (PKU) is hypothesized to be a conformational disease, with loss of function due to protein destabilization, and the restoration of enzyme function that is observed in BH(4) treatment might be transmitted by correction of protein misfolding. To elucidate the molecular basis of functional impairment in PAH deficiency, we investigated the impact of ten PAH gene mutations identified in patients with BH(4)-responsiveness on enzyme kinetics, stability, and conformation of the protein (F55L, I65S, H170Q, P275L, A300S, S310Y, P314S, R408W, Y414C, Y417H). Residual enzyme activity was generally high, but allostery was disturbed in almost all cases and pointed to altered protein conformation. This was confirmed by reduced proteolytic stability, impaired tetramer assembly or aggregation, increased hydrophobicity, and accelerated thermal unfolding--with particular impact on the regulatory domain--observed in most variants. Three-dimensional modeling revealed the involvement of functionally relevant amino acid networks that may communicate misfolding throughout the protein. Our results substantiate the view that PAH deficiency is a protein-misfolding disease in which global conformational changes hinder molecular motions essential for physiological enzyme function. Thus, PKU has evolved from a model of a genetic disease that leads to severe neurological impairment to a model of a treatable protein-folding disease with loss of function.
AB - A significant share of patients with phenylalanine hydroxylase (PAH) deficiency benefits from pharmacological doses of tetrahydrobiopterin (BH(4)), the natural PAH cofactor. Phenylketonuria (PKU) is hypothesized to be a conformational disease, with loss of function due to protein destabilization, and the restoration of enzyme function that is observed in BH(4) treatment might be transmitted by correction of protein misfolding. To elucidate the molecular basis of functional impairment in PAH deficiency, we investigated the impact of ten PAH gene mutations identified in patients with BH(4)-responsiveness on enzyme kinetics, stability, and conformation of the protein (F55L, I65S, H170Q, P275L, A300S, S310Y, P314S, R408W, Y414C, Y417H). Residual enzyme activity was generally high, but allostery was disturbed in almost all cases and pointed to altered protein conformation. This was confirmed by reduced proteolytic stability, impaired tetramer assembly or aggregation, increased hydrophobicity, and accelerated thermal unfolding--with particular impact on the regulatory domain--observed in most variants. Three-dimensional modeling revealed the involvement of functionally relevant amino acid networks that may communicate misfolding throughout the protein. Our results substantiate the view that PAH deficiency is a protein-misfolding disease in which global conformational changes hinder molecular motions essential for physiological enzyme function. Thus, PKU has evolved from a model of a genetic disease that leads to severe neurological impairment to a model of a treatable protein-folding disease with loss of function.
KW - Administration, Oral
KW - Allosteric Regulation
KW - Amino Acid Metabolism, Inborn Errors
KW - Amino Acid Sequence
KW - Amino Acid Substitution
KW - Binding Sites
KW - Biopterin
KW - Catalytic Domain
KW - Computer Simulation
KW - Dimerization
KW - Endopeptidase K
KW - Enzyme Stability
KW - Female
KW - Hot Temperature
KW - Humans
KW - Hydrogen Bonding
KW - Hydrolysis
KW - Hydrophobic and Hydrophilic Interactions
KW - Infant, Newborn
KW - Kinetics
KW - Luminescence
KW - Male
KW - Models, Molecular
KW - Motion
KW - Mutation, Missense
KW - Phenylalanine
KW - Phenylalanine Hydroxylase
KW - Phenylketonurias
KW - Protein Conformation
KW - Protein Denaturation
KW - Protein Folding
KW - Protein Structure, Secondary
KW - Protein Structure, Tertiary
KW - Protein Subunits
KW - Recombinant Fusion Proteins
KW - Static Electricity
U2 - 10.1016/j.ajhg.2008.05.013
DO - 10.1016/j.ajhg.2008.05.013
M3 - SCORING: Journal article
C2 - 18538294
VL - 83
SP - 5
EP - 17
JO - AM J HUM GENET
JF - AM J HUM GENET
SN - 0002-9297
IS - 1
ER -