The ferrochelatase from Saccharomyces cerevisiae. Sequence, disruption, and expression of its structural gene HEM15.
The HEM15 gene in Saccharomyces cerevisiae encodes ferrochelatase (EC 4.99.1.1, protoheme ferrolyase), a mitochondrial inner membrane-bound enzyme which catalyzes the insertion of ferrous ion into protoporphyrin IX, the last step in protoheme biosynthesis. The gene was isolated by functional complementation of a hem15 mutant. Sequence analysis of a 2.9-kilobase genomic DNA fragment revealed an open reading frame of 1179 nucleotides, plus a gene coding for a tRNA(Val)(GUU) and delta elements downstream from the 3'-end of HEM15. The open reading frame encodes a precursor form of the protein containing a 31-amino acid presequence. The mature enzyme contains 362 amino acid residues; its calculated molecular weight (40,900) and predicted amino-terminal sequence agree with those determined from the purified protein. It is relatively abundant in lysine (9%) and contains no apparent transmembrane segment. Disruption of the HEM15 gene led to non-viable cells in certain genetic background. Northern (RNA) analysis showed a slight (1.5-2-fold) repression of HEM15 expression by glucose.
Labbe-Bois
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Institut Jacques Monod, Laboratoire de Biochimie des Porphyrines, Université Paris VII, France.
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D003062:Codon / Q000235:genetics; D004271:DNA, Fungal / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000235:genetics; D005294:Ferrochelatase / Q000235:genetics*; D015870:Gene Expression; D005800:Genes, Fungal; D008190:Lyases / Q000235:genetics*; D008969:Molecular Sequence Data; D010957:Plasmids; D011487:Protein Conformation; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics*
D003062:Codon; D004271:DNA, Fungal; D008190:Lyases; D005294:Ferrochelatase