Limits...
Turning Saccharomyces cerevisiae into a Frataxin-Independent Organism.

Yoon H, Knight SA, Pandey A, Pain J, Turkarslan S, Pain D, Dancis A - PLoS Genet. (2015)

Bottom Line: Yeast Isu1 with the methionine to isoleucine substitution (M141I), in which the E. coli amino acid is inserted at this position, corrected most of the phenotypes that result from lack of Yfh1 in yeast.The frataxin-bypassing amino acids Cys, Ile, Leu, or Val, were found predominantly in prokaryotes.This amino acid position 141 is unique in Isu1, and the frataxin-bypass effect likely mimics a conserved and ancient feature of the prokaryotic Fe-S cluster assembly machinery.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.

ABSTRACT
Frataxin (Yfh1 in yeast) is a conserved protein and deficiency leads to the neurodegenerative disease Friedreich's ataxia. Frataxin is a critical protein for Fe-S cluster assembly in mitochondria, interacting with other components of the Fe-S cluster machinery, including cysteine desulfurase Nfs1, Isd11 and the Isu1 scaffold protein. Yeast Isu1 with the methionine to isoleucine substitution (M141I), in which the E. coli amino acid is inserted at this position, corrected most of the phenotypes that result from lack of Yfh1 in yeast. This suppressor Isu1 behaved as a genetic dominant. Furthermore frataxin-bypass activity required a completely functional Nfs1 and correlated with the presence of efficient scaffold function. A screen of random Isu1 mutations for frataxin-bypass activity identified only M141 substitutions, including Ile, Cys, Leu, or Val. In each case, mitochondrial Nfs1 persulfide formation was enhanced, and mitochondrial Fe-S cluster assembly was improved in the absence of frataxin. Direct targeting of the entire E. coli IscU to ∆yfh1 mitochondria also ameliorated the mutant phenotypes. In contrast, expression of IscU with the reverse substitution i.e. IscU with Ile to Met change led to worsening of the ∆yfh1 phenotypes, including severely compromised growth, increased sensitivity to oxygen, deficiency in Fe-S clusters and heme, and impaired iron homeostasis. A bioinformatic survey of eukaryotic Isu1/prokaryotic IscU database entries sorted on the amino acid utilized at the M141 position identified unique groupings, with virtually all of the eukaryotic scaffolds using Met, and the preponderance of prokaryotic scaffolds using other amino acids. The frataxin-bypassing amino acids Cys, Ile, Leu, or Val, were found predominantly in prokaryotes. This amino acid position 141 is unique in Isu1, and the frataxin-bypass effect likely mimics a conserved and ancient feature of the prokaryotic Fe-S cluster assembly machinery.

No MeSH data available.


Related in: MedlinePlus

Cosegregation of Isu1/IscU-M and frataxin in global taxonomy.Distribution of species containing M (red letter) versus C I L V (blue letters) at the X position of the motif LPPVK LH CSX LA and correlation with the presence of frataxin. The presence of frataxin is indicated by a red colored box next to each species in the taxonomic tree. The depicted species were chosen to maximize diversity. The species are displayed using the NCBI Taxonomy browser according to their positions in the NCBI Taxonomy Database. The arrow connecting shaded areas in Proteobacteria and Eukaryota represents the direction of possible horizontal gene transfer occurring during mitochondrial creation.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4440810&req=5

pgen.1005135.g006: Cosegregation of Isu1/IscU-M and frataxin in global taxonomy.Distribution of species containing M (red letter) versus C I L V (blue letters) at the X position of the motif LPPVK LH CSX LA and correlation with the presence of frataxin. The presence of frataxin is indicated by a red colored box next to each species in the taxonomic tree. The depicted species were chosen to maximize diversity. The species are displayed using the NCBI Taxonomy browser according to their positions in the NCBI Taxonomy Database. The arrow connecting shaded areas in Proteobacteria and Eukaryota represents the direction of possible horizontal gene transfer occurring during mitochondrial creation.

Mentions: Sorting on this position revealed highly interesting groupings. Firstly, we found that Isu1/IscU sequences with Met were present almost exclusively in eukaryotic species (302 of 307 entries, S2 Table). The converse was also true i.e. eukaryotic species had Isu1/IscU with Met present in almost all cases. The proteins with Met at position X were found in the most diverse branches of eukaryotes, including Excavata that lack classical mitochondria, Chromalveolata, various yeasts including Zygomycota, Basidiomycota, Ascomycota, land plants, photosynthetic single-celled organisms, various metazoans including worms, fish, flies, mice and humans (Fig 6). The only significant exceptions to the rule that Isu1/IscU with Met occurs in eukaryotes were several proteobacterial rickettsial species, including Holospora undulata, Neorickettsia risticii, Neorickettsia sennetsu, and Orientia tsutsugamushi. These organisms are intracellular parasites that are the closest living relatives of mitochondria. Interestingly, all these species have retained frataxin in their genomes [1], suggesting that IscU-Met and frataxin may have been co-inherited with the rest of the Fe-S cluster assembly machinery during the endosymbiotic event that gave rise to mitochondria (Fig 6) [1].


Turning Saccharomyces cerevisiae into a Frataxin-Independent Organism.

Yoon H, Knight SA, Pandey A, Pain J, Turkarslan S, Pain D, Dancis A - PLoS Genet. (2015)

Cosegregation of Isu1/IscU-M and frataxin in global taxonomy.Distribution of species containing M (red letter) versus C I L V (blue letters) at the X position of the motif LPPVK LH CSX LA and correlation with the presence of frataxin. The presence of frataxin is indicated by a red colored box next to each species in the taxonomic tree. The depicted species were chosen to maximize diversity. The species are displayed using the NCBI Taxonomy browser according to their positions in the NCBI Taxonomy Database. The arrow connecting shaded areas in Proteobacteria and Eukaryota represents the direction of possible horizontal gene transfer occurring during mitochondrial creation.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440810&req=5

pgen.1005135.g006: Cosegregation of Isu1/IscU-M and frataxin in global taxonomy.Distribution of species containing M (red letter) versus C I L V (blue letters) at the X position of the motif LPPVK LH CSX LA and correlation with the presence of frataxin. The presence of frataxin is indicated by a red colored box next to each species in the taxonomic tree. The depicted species were chosen to maximize diversity. The species are displayed using the NCBI Taxonomy browser according to their positions in the NCBI Taxonomy Database. The arrow connecting shaded areas in Proteobacteria and Eukaryota represents the direction of possible horizontal gene transfer occurring during mitochondrial creation.
Mentions: Sorting on this position revealed highly interesting groupings. Firstly, we found that Isu1/IscU sequences with Met were present almost exclusively in eukaryotic species (302 of 307 entries, S2 Table). The converse was also true i.e. eukaryotic species had Isu1/IscU with Met present in almost all cases. The proteins with Met at position X were found in the most diverse branches of eukaryotes, including Excavata that lack classical mitochondria, Chromalveolata, various yeasts including Zygomycota, Basidiomycota, Ascomycota, land plants, photosynthetic single-celled organisms, various metazoans including worms, fish, flies, mice and humans (Fig 6). The only significant exceptions to the rule that Isu1/IscU with Met occurs in eukaryotes were several proteobacterial rickettsial species, including Holospora undulata, Neorickettsia risticii, Neorickettsia sennetsu, and Orientia tsutsugamushi. These organisms are intracellular parasites that are the closest living relatives of mitochondria. Interestingly, all these species have retained frataxin in their genomes [1], suggesting that IscU-Met and frataxin may have been co-inherited with the rest of the Fe-S cluster assembly machinery during the endosymbiotic event that gave rise to mitochondria (Fig 6) [1].

Bottom Line: Yeast Isu1 with the methionine to isoleucine substitution (M141I), in which the E. coli amino acid is inserted at this position, corrected most of the phenotypes that result from lack of Yfh1 in yeast.The frataxin-bypassing amino acids Cys, Ile, Leu, or Val, were found predominantly in prokaryotes.This amino acid position 141 is unique in Isu1, and the frataxin-bypass effect likely mimics a conserved and ancient feature of the prokaryotic Fe-S cluster assembly machinery.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Division of Hematology-Oncology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America.

ABSTRACT
Frataxin (Yfh1 in yeast) is a conserved protein and deficiency leads to the neurodegenerative disease Friedreich's ataxia. Frataxin is a critical protein for Fe-S cluster assembly in mitochondria, interacting with other components of the Fe-S cluster machinery, including cysteine desulfurase Nfs1, Isd11 and the Isu1 scaffold protein. Yeast Isu1 with the methionine to isoleucine substitution (M141I), in which the E. coli amino acid is inserted at this position, corrected most of the phenotypes that result from lack of Yfh1 in yeast. This suppressor Isu1 behaved as a genetic dominant. Furthermore frataxin-bypass activity required a completely functional Nfs1 and correlated with the presence of efficient scaffold function. A screen of random Isu1 mutations for frataxin-bypass activity identified only M141 substitutions, including Ile, Cys, Leu, or Val. In each case, mitochondrial Nfs1 persulfide formation was enhanced, and mitochondrial Fe-S cluster assembly was improved in the absence of frataxin. Direct targeting of the entire E. coli IscU to ∆yfh1 mitochondria also ameliorated the mutant phenotypes. In contrast, expression of IscU with the reverse substitution i.e. IscU with Ile to Met change led to worsening of the ∆yfh1 phenotypes, including severely compromised growth, increased sensitivity to oxygen, deficiency in Fe-S clusters and heme, and impaired iron homeostasis. A bioinformatic survey of eukaryotic Isu1/prokaryotic IscU database entries sorted on the amino acid utilized at the M141 position identified unique groupings, with virtually all of the eukaryotic scaffolds using Met, and the preponderance of prokaryotic scaffolds using other amino acids. The frataxin-bypassing amino acids Cys, Ile, Leu, or Val, were found predominantly in prokaryotes. This amino acid position 141 is unique in Isu1, and the frataxin-bypass effect likely mimics a conserved and ancient feature of the prokaryotic Fe-S cluster assembly machinery.

No MeSH data available.


Related in: MedlinePlus