Structure of the gene encoding the entire mature E1α subunit of human branched-chain α-keto acid dehydrogenase complex

Abstract

We report the isolation of a 22-kb human genomic clone (G7) that contains 8 exons encoding a partial mitochondrial presequence, the entire mature peptide and the complete 3′ untranslated region of the E1α mRNA of human branched-chain α-keto acid dehydrogenase complex. Based on this gene structure, exon 9 contains the Tyr 393 → Asn mutation previously identified in the E1α subunit of Mennonite and other maple syrup urine disease (MSUD) patients. Moreover, the homozygous mutation appears to cause skipping of exon 6 in the mutant E1α transcript. The information on the gene structure for the entire mature E1α subunit will facilitate investigations into the molecular basis of MSUD involving this subunit.