Molecular analysis of HEM6 (HEM12) in Saccharomyces cerevisiae, the gene for uroporphyrinogen decarboxylase

Abstract

HEM6 (HEM12) in Saccharomyces cerevisiae encodes uroporphyrinogen decarboxylase, the fifth enzyme in the heme biosynthetic pathway. The HEM6 (HEM12) gene was cloned by complementation of heme auxotrophy of a hem6 mutant. Sequence analysis revealed an open reading frame of 1086 nucleotides. The predicted amino acid sequence of HEM6 (HEM12) shows extensive homology to those reported for uroporphyrinogen decarboxylase from mammalian sources. Expression of HEM6 (HEM12) was investigated and was found to increase two-fold in a non-fermentable carbon source. However, HEM6 (HEM12) transcription was unaffected by heme or by intermediates in the heme biosynthetic pathway. In addition, HEM6 (HEM12) expression is not regulated by the transcriptional activator complex HAP2-3-4, as has been shown for some genes encoding heme biosynthetic enzymes.

Kluyveromyces lactis: A Suitable Yeast Model to Study Cellular Defense Mechanisms against Hypoxia-Induced Oxidative Stress

“…For the three genes of the heme biosynthetic pathway characterized in K. lactis to date ( KlHEM1 , KlHEM12 ,and KlHEM13) , functional equivalence with their S. cerevisiae homologs has been confirmed experimentally by cross-complementation [31, 32, 37]. As it happens in S. cerevisiae , the transcriptional regulation of KlHEM12 is not a key point for regulation of heme synthesis in K. lactis [38] and its transcriptional regulation in different carbon sources [38] is also similar to that reported for its homolog in S. cerevisiae [39, 40]. However, notable differences exist in the regulation of the other two characterized genes.…”

Sampangine Inhibits Heme Biosynthesis in both Yeast and Human

“…It is possible that hyperactivation of PBGD and/or UIIIS disrupts the balance within the entire heme synthesis pathway and leads to decreased heme levels. To test this hypothesis, we measured cellular levels of hemin in yeast strains that overexpress HEM3, HEM4, and HEM12, genes encoding PBGD, UIIIS, and UroD, respectively (2,10,18), from high-copy-number plasmids. Overexpressing both HEM3 and HEM12 increased heme levels in yeast cells, and these effects were blocked by sampangine treatment (Fig.…”

Mouse uroporphyrinogen decarboxylase: CDNA cloning, expression, and mapping

“…In human, rat, and mouse, the regions of nucleotide and predicted amino acid homology were distributed throughout the entire open reading frame, disrupted only by short stretches of no more than five nonhomologous nucleotides or three different amino acids. In contrast, the amino acid identity was lower between the mouse sequence and the URO-decarboxylase coding region from Saccharomyces cerevisiae [48.8% with 25 gaps (gap = two or more amino acids) (Diflumeri et al 1993)], Synechococcus sp. (35.1% with 31 gaps) (Kiel et al 1992), Bacillus subtilis (34.8% with 29 gaps; Hansson and Hederstedt 1992), R. capsulatus (33.2% with 29 gaps; Ineichen and Biel 1994; Fig.…”

“…In addition, a partial URO-decarboxylase cDNA from rat spleen (Romeo et al 1984) and the prokaryotic genes encoding the enzyme from Bacillus subtilis, Escherichia coli bacter capsulatus, Synechococcus sp. PCC7942, and Saccharomyces cerevisiae have been isolated and sequenced (Hansson and Hederstedt 1992;Nishimura et al 1993;Kiel et al 1992;Diflumeri et al 1993).…”