A conserved cysteine residue in yeast uroporphyrinogen decarboxylase is not essential for enzymatic activity
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Updated: Aug 9, 2026

Growth-based Determination and Biochemical Confirmation of Genetic Requirements for Protein Degradation in Saccharomyces cerevisiae
Published on: February 16, 2015
C Di Flumeri1, N H Acheson, T Keng
1Department of Microbiology and Immunology, McGill University, Montréal, QC, Canada. charlie@nexus.microimm.mcgill.ca
Abstract:
Uroporphyrinogen decarboxylase catalyzes the fifth step of heme biosynthesis in Saccharomyces cerevisiae. Studies utilizing sulfhydryl-specific reagents suggest that the enzyme requires a cysteine residue within the catalytic site. This hypothesis was tested directly by site-directed mutagenesis of highly conserved cysteine-52 to serine or alanine. Plasmids containing these mutations were able to complement a hem6 mutant strain. In addition, properties associated with decreased uroporphyrinogen decarboxylase activity were not detected in the mutant strain transformed with these mutant plasmids. These results suggest that the conserved cysteine-52 by itself is not essential for enzymatic activity.
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