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Title: Mutations in the PCCA gene encoding the {alpha} subunit of propionyl-CoA carboxylase in patients with propionic acidemia

Abstract

Propionic acidemia is a rare autosomal recessive disorder characterized by a deficiency of the mitochondrial biotin-dependent enzyme, propionyl-CoA carboxylase (PCC). PCC has the structure {alpha}{sub 4}{beta}{sub 4}, with the {alpha} subunit containing the biotin prosthetic group. This study is concerned with defining the spectrum of mutations occurring in the PCCA gene encoding the {alpha} subunit. Mutations were initially assigned to this gene through complementation experiments done after somatic fusion of patient fibroblasts. The analyses were performed on PCR-amplified reverse transcripts of fibroblast RNA. The mutations were identified by single strand conformational polymorphism analysis and direct sequencing of PCR products. Three candidate disease-causing mutations and one DNA polymorphism were identified in the {alpha} subunit sequence in different patients: (1) a 3 bp deletion {triangle}CTG{sub 2058-2060}, which eliminates Cys687 near the biotin binding site (Lys669); (2) T{sub 611}{r_arrow}A which converts Met204 to Lys in a highly conserved region matching that of an ATP binding site; (3) An {approximately}50 bp deletion near the 3{prime} end of the cDNA which likely corresponds to the loss of an exon due to a splicing defect; and (4) a 3 bp insertion, +CAG{sub 2203}, located downstream of the stop codon, which is likely a DNA polymorphism. Inmore » order to determine the effect of the Cys687 deletion on the biotinylation of PCC, we expressed the mutation in a 67 amino acid C-terminal fragment of the PCC {alpha} subunit in E. coli in which biotinylation is directed by the bacterial biotin ligase. While the mutant peptide was expressed at about half-normal levels, the biotinylation of the peptide that was present was reduced to only {approximately}20% normal. We suggest, therefore, that the absence of PCC activity due to {triangle}Cys687 results at least in part from defective biotinylation of an unstable protein.« less

Authors:
; ;  [1]
  1. McGill Univ., Quebec (Canada)
Publication Date:
OSTI Identifier:
133424
Report Number(s):
CONF-941009-
Journal ID: AJHGAG; ISSN 0002-9297; TRN: 95:005313-0152
Resource Type:
Journal Article
Resource Relation:
Journal Name: American Journal of Human Genetics; Journal Volume: 55; Journal Issue: Suppl.3; Conference: 44. annual meeting of the American Society of Human Genetics, Montreal (Canada), 18-22 Oct 1994; Other Information: PBD: Sep 1994
Country of Publication:
United States
Language:
English
Subject:
55 BIOLOGY AND MEDICINE, BASIC STUDIES; GENES; GENE MUTATIONS; TRANSCRIPTION; SPLICING; PATIENTS; RECESSIVE MUTATIONS; HEREDITARY DISEASES; ENZYMES; STRUCTURE-ACTIVITY RELATIONSHIPS; FIBROBLASTS; SOMATIC MUTATIONS; BIOTIN; POLYMERASE CHAIN REACTION; RNA; PROTEINS; ESCHERICHIA COLI

Citation Formats

Campeau, E., Leon-Del-Rio, A., and Gravel, R.A. Mutations in the PCCA gene encoding the {alpha} subunit of propionyl-CoA carboxylase in patients with propionic acidemia. United States: N. p., 1994. Web.
Campeau, E., Leon-Del-Rio, A., & Gravel, R.A. Mutations in the PCCA gene encoding the {alpha} subunit of propionyl-CoA carboxylase in patients with propionic acidemia. United States.
Campeau, E., Leon-Del-Rio, A., and Gravel, R.A. Thu . "Mutations in the PCCA gene encoding the {alpha} subunit of propionyl-CoA carboxylase in patients with propionic acidemia". United States.
@article{osti_133424,
title = {Mutations in the PCCA gene encoding the {alpha} subunit of propionyl-CoA carboxylase in patients with propionic acidemia},
author = {Campeau, E. and Leon-Del-Rio, A. and Gravel, R.A.},
abstractNote = {Propionic acidemia is a rare autosomal recessive disorder characterized by a deficiency of the mitochondrial biotin-dependent enzyme, propionyl-CoA carboxylase (PCC). PCC has the structure {alpha}{sub 4}{beta}{sub 4}, with the {alpha} subunit containing the biotin prosthetic group. This study is concerned with defining the spectrum of mutations occurring in the PCCA gene encoding the {alpha} subunit. Mutations were initially assigned to this gene through complementation experiments done after somatic fusion of patient fibroblasts. The analyses were performed on PCR-amplified reverse transcripts of fibroblast RNA. The mutations were identified by single strand conformational polymorphism analysis and direct sequencing of PCR products. Three candidate disease-causing mutations and one DNA polymorphism were identified in the {alpha} subunit sequence in different patients: (1) a 3 bp deletion {triangle}CTG{sub 2058-2060}, which eliminates Cys687 near the biotin binding site (Lys669); (2) T{sub 611}{r_arrow}A which converts Met204 to Lys in a highly conserved region matching that of an ATP binding site; (3) An {approximately}50 bp deletion near the 3{prime} end of the cDNA which likely corresponds to the loss of an exon due to a splicing defect; and (4) a 3 bp insertion, +CAG{sub 2203}, located downstream of the stop codon, which is likely a DNA polymorphism. In order to determine the effect of the Cys687 deletion on the biotinylation of PCC, we expressed the mutation in a 67 amino acid C-terminal fragment of the PCC {alpha} subunit in E. coli in which biotinylation is directed by the bacterial biotin ligase. While the mutant peptide was expressed at about half-normal levels, the biotinylation of the peptide that was present was reduced to only {approximately}20% normal. We suggest, therefore, that the absence of PCC activity due to {triangle}Cys687 results at least in part from defective biotinylation of an unstable protein.},
doi = {},
journal = {American Journal of Human Genetics},
number = Suppl.3,
volume = 55,
place = {United States},
year = {Thu Sep 01 00:00:00 EDT 1994},
month = {Thu Sep 01 00:00:00 EDT 1994}
}