title: Identification of human ferritin, heavy polypeptide 1 (FTH1) and yeast RGI1 (YER067W) as pro-survival sequences that counteract the effects of Bax and copper in Saccharomyces cerevisiae.
abstract: Ferritin is a sub-family of iron binding proteins that form multi-subunit nanotype iron storage structures and prevent oxidative stress induced apoptosis. Here we describe the identification and characterization of human ferritin, heavy polypeptide 1 (FTH1) as a suppressor of the pro-apoptotic murine Bax sequence in yeast. In addition we demonstrate that FTH1 is a general pro-survival sequence since it also prevents the cell death inducing effects of copper when heterologously expressed in yeast. Although ferritins are phylogenetically widely distributed and are present in most species of Bacteria, Archaea and Eukarya, ferritin is conspicuously absent in most fungal species including Saccharomyces cerevisiae. An in silico analysis of the yeast proteome lead to the identification of the 161 residue RGI1 (YER067W) encoded protein as a candidate for being a yeast ferritin. In addition to sharing 20% sequence identity with the 183 residue FTH1, RGI1 also has similar pro-survival properties as ferritin when overexpressed in yeast. Analysis of recombinant protein by SDS-PAGE and by electron microscopy revealed the expected formation of higher-order structures for FTH1 that was not observed with Rgi1p. Further analysis revealed that cells overexpressing RGI1 do not show increased resistance to iron toxicity and do not have enhanced capacity to store iron. In contrast, cells lacking RGI1 were found to be hypersensitive to the toxic effects of iron. Overall, our results suggest that Rgi1p is a novel pro-survival protein whose function is not related to ferritin but nevertheless it may have a role in regulating yeast sensitivity to iron stress.
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada; Department of Biology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Rawan
authors.initials: R
authors.lastname: Eid
authors.affiliation: Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
authors.forename: Eric
authors.initials: E
authors.lastname: Boucher
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada.
authors.forename: Nada
authors.initials: N
authors.lastname: Gharib
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada; Department of Biology, Queen's University, Kingston, Ontario, Canada; Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
authors.forename: Chamel
authors.initials: C
authors.lastname: Khoury
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada; Department of Biology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Nagla T T
authors.initials: NT
authors.lastname: Arab
authors.affiliation: Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
authors.forename: Alistair
authors.initials: A
authors.lastname: Murray
authors.affiliation: Department of Biology, Queen's University, Kingston, Ontario, Canada.
authors.forename: Paul G
authors.initials: PG
authors.lastname: Young
authors.affiliation: Department of Anatomy and Cell Biology, McGill University, Montreal, Quebec, Canada.
authors.forename: Craig A
authors.initials: CA
authors.lastname: Mandato
authors.affiliation: Department of Chemistry and Chemical Engineering, Royal Military College, Kingston, Ontario, Canada. Electronic address: michael.greenwood@rmc.ca.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Greenwood
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002712:Chlorides / Q000494:pharmacology; D019327:Copper Sulfate / Q000494:pharmacology*; D005290:Ferric Compounds / Q000494:pharmacology; D005293:Ferritins / Q000737:chemistry / Q000502:physiology*; D006801:Humans; D051379:Mice; D050296:Microbial Viability; D008969:Molecular Sequence Data; D010088:Oxidoreductases; D012441:Saccharomyces cerevisiae / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000502:physiology*; D017386:Sequence Homology, Amino Acid; D013312:Stress, Physiological; D051028:bcl-2-Associated X Protein / Q000502:physiology*
chemical_list: C494827:Bax protein, mouse; D002712:Chlorides; D005290:Ferric Compounds; C551793:RGI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D051028:bcl-2-Associated X Protein; D005293:Ferritins; C454461:FTH1 protein, human; D010088:Oxidoreductases; D019327:Copper Sulfate; C024555:ferric chloride
keywords: Anti-apoptosis; Copper; Ferritin; Iron; Pro-survival; Recombinant ferritin