Functional studies of mutations in the human protoporphyrinogen oxidase gene in variegate porphyria.

Abstract

The autosomal dominant disorder, variegate porphyria (VP), results from mutations in the protoporphyrinogen oxidase (PPOX) gene. We have investigated the effects of 22 disease-associated missense mutations in this gene on enzyme activity. Mutants were generated in the expression plasmid pHPPOX by site-directed mutagenesis. They were screened for PPOX activity by complementation of the Escherischia coli strain SAS38X which lacks PPOX activity. Ten mutants (G40E, L85P, G232R, de1281H, V282D, L295P, V335G, S350P, L444P, G453V) had no detectable PPOX activity. PPOX activity of the remaining 12 mutants (L15F, R38P, L73P, V84G, D143V, R152C, L154P, V158M, R168H, A172V, V290L, G453R) ranged from less than 1% to 9.2% of wild-type activity. Our findings show that all 22 mutations substantially impair or abolish PPOX activity in a prokaryotic expression system and add to the evidence that they cause VP.

• Authors: Rhian R Morgan, Silva Vasco da, Hervé Puy, Jean-Charles Deybach, George H Elder
• Journal: Cellular and molecular biology (Noisy-le-Grand, France) (Cell Mol Biol (Noisy-le-grand)) Vol. 48 Issue 1 Pg. 79-82 (Feb 2002) ISSN: 0145-5680 [Print] France
• PMID: 11929051 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Flavoproteins
• Mitochondrial Proteins
• Oxidoreductases
• Oxidoreductases Acting on CH-CH Group Donors
• PPOX protein, human
• Protoporphyrinogen Oxidase

Topics

• Escherichia coli (enzymology, genetics)
• Flavoproteins
• Gene Expression (genetics)
• Genetic Complementation Test
• Humans
• Mitochondrial Proteins
• Mutagenesis, Site-Directed
• Mutation, Missense (genetics)
• Oxidoreductases (genetics, metabolism)
• Oxidoreductases Acting on CH-CH Group Donors
• Porphyrias, Hepatic (enzymology, genetics)
• Protoporphyrinogen Oxidase