Metal binding to Saccharomyces cerevisiae ferrochelatase.

Ferrochelatase is the terminal enzyme in the heme biosynthetic pathway. It catalyzes the insertion of ferrous iron into protoporphyrin IX to produce protoheme IX. The crystal structures of ferrochelatase from Saccharomyces cerevisiae in free form, in complex with Co(II), a substrate metal ion, and in complex with two inhibitors, Cd(II) and Hg(I), are presented in this work.

Activity and cellular location in Saccharomyces cerevisiae of chimeric mouse/yeast and Bacillus subtilis/yeast ferrochelatases.

We have constructed a series of chimeric yeast/mouse and yeast/Bacillus subtilis ferrochelatase genes in order to investigate domains of the ferrochelatase that are important for activity and/or association with the membrane. These genes were expressed in a Saccharomyces cerevisiae mutant in which the endogenous ferrochelatase gene (HEM15) had been deleted, and the phenotypes of the transformants were characterized. Exchanging the approximately 40-amino-acid C-terminus between the yeast and mouse ferrochelatases caused a total loss of activity and the hybrid proteins were unstable when overproduced in Escherichia coli.

Flavohemoglobin expression and function in Saccharomyces cerevisiae. No relationship with respiration and complex response to oxidative stress.

The yeast Saccharomyces cerevisiae contains a flavohemoglobin, encoded by the gene YHB1, whose function is unclear. Previous reports presented evidence that its maximal expression requires disruption of mitochondrial respiration and that it plays a role in the response to oxidative stress. We have studied the expression of YHB1 in respiratory deficient cells and in cells exposed to various compounds causing oxidative stress.

Characterization of an upstream activation sequence and two Rox1p-responsive sites controlling the induction of the yeast HEM13 gene by oxygen and heme deficiency.

The Saccharomyces cerevisiae HEM13 gene codes for coproporphyrinogen oxidase, an oxygen-requiring enzyme catalyzing the sixth step of heme biosynthesis. Its transcription has been shown to be induced 40-50-fold in response to oxygen or heme deficiency, in part through relief of repression exerted by Rox1p and in part by activation mediated by an upstream activation sequence (UAS). This report describes an analysis of HEM13 UAS and of the Rox1p-responsive sites by electrophoretic mobility shift assays, DNase I footprinting, and mutational mapping.

Probing the active-site residues in Saccharomyces cerevisiae ferrochelatase by directed mutagenesis. In vivo and in vitro analyses.

Ferrochelatase is a mitochondrial inner membrane-bound enzyme that catalyzes the insertion of ferrous iron into protoporphyrin, the terminal step in protoheme biosynthesis. The functional/structural roles of 10 invariant amino acid residues were investigated by site-directed mutagenesis in the yeast Saccharomyces cerevisiae ferrochelatase. The mutant enzymes were expressed in a yeast strain lacking the ferrochelatase gene HEM15 and in Escherichia coli.