Isolation of a cDNA encoding human holocarboxylase synthetase by functional complementation of a biotin auxotroph of Escherichia coli.

DOI Web Site 被引用文献5件
  • A León-Del-Rio
    McGill University-Montreal Children's Hospital Research Institute, QC, Canada.
  • D Leclerc
    McGill University-Montreal Children's Hospital Research Institute, QC, Canada.
  • B Akerman
    McGill University-Montreal Children's Hospital Research Institute, QC, Canada.
  • N Wakamatsu
    McGill University-Montreal Children's Hospital Research Institute, QC, Canada.
  • R A Gravel
    McGill University-Montreal Children's Hospital Research Institute, QC, Canada.

抄録

<jats:p>Holocarboxylase synthetase (HCS) catalyzes the biotinylation of the four biotin-dependent carboxylases in human cells. Patients with HCS deficiency lack activity of all four carboxylases, indicating that a single HCS is targeted to the mitochondria and cytoplasm. We isolated 21 human HCS cDNA clones, in four size classes of 2.0-4.0 kb, by complementation of an Escherichia coli birA mutant defective in biotin ligase. Expression of the cDNA clones promoted biotinylation of the bacterial biotinyl carboxyl carrier protein as well as a carboxyl-terminal fragment of the alpha subunit of human propionyl-CoA carboxylase expressed from a plasmid. The open reading frame encodes a predicted protein of 726 aa and M(r) 80,759. Northern blot analysis revealed the presence of a 5.8-kb major species and 4.0-, 4.5-, and 8.5-kb minor species of poly(A)+ RNA in human tissues. Human HCS shows specific regions of homology with the BirA protein of E. coli and the presumptive biotin ligase of Paracoccus denitrificans. Several forms of HCS mRNA are generated by alternative splicing, and as a result, two mRNA molecules bear different putative translation initiation sites. A sequence upstream of the first translation initiation site encodes a peptide structurally similar to mitochondrial presequences, but it lacks an in-frame ATG codon to direct its translation. We anticipate that alternative splicing most likely mediates the mitochondrial versus cytoplasmic expression, although the elements required for directing the enzyme to the mitochondria remain to be confirmed.</jats:p>

収録刊行物

被引用文献 (5)*注記

もっと見る

キーワード

詳細情報 詳細情報について

問題の指摘

ページトップへ