Structural (betaalpha)8 TIM barrel model of 3-hydroxy-3-methylglutaryl-coenzyme A lyase.
This study describes three novel homozygous missense mutations (S75R, S201Y, and D204N) in the 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) lyase gene, which caused 3-hydroxy-3-methylglutaric aciduria in patients from Germany, England, and Argentina. Expression studies in Escherichia coli show that S75R and S201Y substitutions completely abolished the HMG-CoA lyase activity, whereas D204N reduced catalytic efficiency to 6.6% of the wild type. We also propose a three-dimensional model for human HMG-CoA lyase containing a (betaalpha)8 (TIM) barrel structure. The model is supported by the similarity with analogous TIM barrel structures of functionally related proteins, by the localization of catalytic amino acids at the active site, and by the coincidence between the shape of the substrate (HMG-CoA) and the predicted inner cavity. The three novel mutations explain the lack of HMG-CoA lyase activity on the basis of the proposed structure: in S75R and S201Y because the new amino acid residues occlude the substrate cavity, and in D204N because the mutation alters the electrochemical environment of the active site. We also report the localization of all missense mutations reported to date and show that these mutations are located in the beta-sheets around the substrate cavity.
Casals
Núria
N
Unit of Biochemistry and Molecular Biology, International University of Catalonia, Spain.
Gómez-Puertas
Paulino
P
Pié
Juan
J
Mir
Cecilia
C
Roca
Ramón
R
Puisac
Beatriz
B
Aledo
Rosa
R
Clotet
Josep
J
Menao
Sebastián
S
Serra
Dolors
D
Asins
Guillermina
G
Till
Jacqueline
J
Elias-Jones
Alun C
AC
Cresto
Juan C
JC
Chamoles
Nestor A
NA
Abdenur
Jose E
JE
Mayatepek
Ertan
E
Besley
Guy
G
Valencia
Alfonso
A
Hegardt
Fausto G
FG
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D015870:Gene Expression; D006720:Homozygote; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D015093:Meglutol / Q000652:urine; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D016297:Mutagenesis, Site-Directed; D020125:Mutation, Missense; D007652:Oxo-Acid-Lyases / Q000737:chemistry* / Q000172:deficiency* / Q000235:genetics; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins; D016415:Sequence Alignment
D011994:Recombinant Proteins; D015093:Meglutol; D007652:Oxo-Acid-Lyases; C021410:3-hydroxy-3-methylglutaryl-coenzyme A lyase