Mitochondrial targeting signals and mature peptides of 3-methylcrotonyl-CoA carboxylase.
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Stadler SC, Polanetz R, Meier S, Mayerhofer PU, Herrmann JM, Anslinger K, Roscher AA, Roschinger W, Holzinger A
Mitochondrial targeting signals and mature peptides of 3-methylcrotonyl-CoA carboxylase.
Biochem Biophys Res Commun. 2005 Sep 2;334(3):939-46.
- PubMed ID
- 16023992 [ View in PubMed]
- Abstract
Inherited deficiency of 3-methylcrotonyl-CoA carboxylase (MCC), an enzyme of leucine degradation, is an organic acidemia detectable by expanded newborn screening with a variable phenotype that ranges from asymptomatic to death in infancy. Here, we show that the two subunits of the enzyme (MCCalpha; MCCbeta) are imported into the mitochondrial matrix by the classical pathway involving cleavable amino-terminal targeting presequences. We identified the cleavage sites (Tyr41/Thr42 and Ala22/Tyr23 for MCCalpha and MCCbeta, respectively) of the targeting signals and the amino-termini of the mature polypeptides of MCC and propionyl-CoA carboxylase, a mitochondrial paralog. The amino-termini containing 39 (MCCalpha) or 20 amino acids (MCCbeta) were both necessary and sufficient for targeting. Structural requirements for mitochondrial import were defined by site-directed mutagenesis. Our studies provide the prerequisite to understand the impact of specific mutations on the clinical phenotype of MCC deficiency.