A putative exonic splicing enhancer in exon 7 of the PDHA1 gene affects splicing of adjacent exons.
A nonsense mutation (c.729C>A, Y243X) in exon 7 of the PDHA1 gene in a patient with pyruvate dehydrogenase deficiency results in aberrant splicing of the primary transcript with production of stable mRNAs which lack either both exons 6 and 7 or exon 7 alone. Transfection and expression of genomic constructs covering exons 5 to 8 of the mutant PDHA1 gene reproduced this aberrant splicing in vitro. The same pattern of abnormal splicing was found when a silent mutation was introduced at the same position. Both the nonsense and silent mutations alter a strong consensus site for the binding of SRp40, suggesting that they may interfere with an exonic splicing enhancer in exon 7 of the gene. However, this appears to affect splicing of not only exon 7, but also the adjacent upstream exon. The splice acceptor site of intron 5 has weak homology to the consensus sequence and this may contribute to the combined splicing defect.
Ridout
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CK
Genetics Unit, Department of Biochemistry, University of Oxford, UK.
Keighley
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P
Krywawych
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Brown
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RM
Brown
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GK
D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002478:Cells, Cultured; D002522:Chlorocebus aethiops; D018389:Codon, Nonsense; D004247:DNA / Q000235:genetics; D004742:Enhancer Elements, Genetic; D005091:Exons; D005822:Genetic Vectors; D006801:Humans; D016297:Mutagenesis, Site-Directed; D030481:Pyruvate Dehydrogenase (Lipoamide) / Q000235:genetics*; D015325:Pyruvate Dehydrogenase Complex Deficiency Disease / Q000201:enzymology / Q000235:genetics; D012326:RNA Splicing / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014162:Transfection
D018389:Codon, Nonsense; D012333:RNA, Messenger; D004247:DNA; D030481:Pyruvate Dehydrogenase (Lipoamide); C065640:pyruvate dehydrogenase E1alpha subunit