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Masuda T, Goto F, Yoshihara T, Ezure T, Suzuki T, Kobayashi S, Shikata M, Utsumi S. Construction of homo- and heteropolymers of plant ferritin subunits using an in vitro protein expression system. Protein Expr Purif 2007; 56:237-46. [PMID: 17904862 DOI: 10.1016/j.pep.2007.07.011] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Revised: 07/20/2007] [Accepted: 07/27/2007] [Indexed: 11/17/2022]
Abstract
Ferritin is a class of iron storage protein composed of 24 subunits. Although many studies on gene expression analyses of plant ferritin have been conducted, the functions and oligomeric assembly of plant ferritin subunits are still largely unknown. In order to characterize the ability to form multimeric protein shells and determine the iron incorporating activity, we produced ferritin homo- and heteropolymers by expressing four cDNAs of ferritin subunits from soybean, sfer1, sfer2, sfer3, and sfer4, using an in vitro protein expression system. Using SDS-PAGE analysis followed by Prussian blue stain, homopolymers of SFER1, SFER2, and SFER3, and heteropolymers of SFER1/SFER2 and SFER1/SFER3 were detected as assembled polymers with iron incorporating activity, whereas only a small amount of SFER4 related homo- and heteropolymer was detected, suggesting that the SFER4 was not competent for oligomeric assembly, unlike every other ferritin. We conclude that certain combinations of plant ferritin subunits can form heteropolymers and that their iron incorporating activities depend on the formation of multimeric protein.
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Affiliation(s)
- Taro Masuda
- Laboratory of Food Quality Design and Development, Division of Agronomy and Horticultural Science, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan.
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102
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Bedekovics T, Gajdos GB, Kispal G, Isaya G. Partial conservation of functions between eukaryotic frataxin and the Escherichia coli frataxin homolog CyaY. FEMS Yeast Res 2007; 7:1276-84. [PMID: 17727661 DOI: 10.1111/j.1567-1364.2007.00296.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Frataxin is a mitochondrial protein structurally conserved from bacteria to humans. Eukaryotic frataxins are known to be involved in the maintenance of mitochondrial iron balance via roles in iron delivery and iron detoxification. The prokaryotic frataxin homolog, CyaY, has been shown to bind and donate iron for the assembly of [2Fe-2S] clusters in vitro. However, in contrast to the severe phenotypes associated with the partial or complete loss of frataxin in humans and other eukaryotes, deletion of the cyaY gene does not cause any obvious alteration of iron balance in bacterial cells, an effect that probably reflects functional redundancy between CyaY and other bacterial proteins. To study CyaY function in a nonredundant setting, we have expressed a mitochondria-targeted form of CyaY in a Saccharomyces cerevisiae strain depleted of the endogenous yeast frataxin protein (yfh1Delta). We show that in this strain CyaY complements to a large extent the loss of iron-sulfur cluster enzyme activities and heme synthesis, and thereby maintains a nearly normal respiratory growth. In addition, CyaY effectively protects yfh1Delta from oxidative damage during treatment with hydrogen peroxide but is less efficient in detoxifying excess labile iron during aerobic growth.
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Affiliation(s)
- Tibor Bedekovics
- Department of Biochemistry and Medical Chemistry, Faculty of Medicine, University of Pécs, Pécs, Hungary.
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103
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Santambrogio P, Biasiotto G, Sanvito F, Olivieri S, Arosio P, Levi S. Mitochondrial ferritin expression in adult mouse tissues. J Histochem Cytochem 2007; 55:1129-37. [PMID: 17625226 PMCID: PMC3957534 DOI: 10.1369/jhc.7a7273.2007] [Citation(s) in RCA: 138] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2007] [Accepted: 06/25/2007] [Indexed: 11/22/2022] Open
Abstract
Mitochondrial ferritin (FtMt) is a novel ferritin type specifically targeted to mitochondria. It is highly expressed in the human testis and in sideroblasts from patients with sideroblastic anemia, but other organs have not been studied. To study its expression in the main organs of the mouse, we first used RT-PCR and then produced recombinant mouse FtMt and specific antibodies. Immunohistochemistry analyses confirmed that FtMt is highly expressed in mouse testis, particularly in spermatocytes and interstitial Leydig cells. The protein was also identified in other organs including heart, brain, spinal cord, kidney, and pancreatic islet of Langerhans but not in liver and splenocytes, which have iron storage function and express high levels of cytosolic ferritins. Results indicate that the primary function of ferritin FtMt is not involved in storing cellular or body iron, but its association with cell types characterized by high metabolic activity and oxygen consumption suggests a role in protecting mitochondria from iron-dependent oxidative damage.
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Affiliation(s)
- Paolo Santambrogio
- Department of Bio Technology, San Raffaele Scientific Institute, Milan, Italy
| | - Giorgio Biasiotto
- Section of Chemistry, Faculty of Medicine, University of Brescia, Brescia, Italy
| | - Francesca Sanvito
- Department of Pathology, San Raffaele Scientific Institute, Milan, Italy
| | - Stefano Olivieri
- Department of Pathology, San Raffaele Scientific Institute, Milan, Italy
| | - Paolo Arosio
- Section of Chemistry, Faculty of Medicine, University of Brescia, Brescia, Italy
| | - Sonia Levi
- Department of Bio Technology, San Raffaele Scientific Institute, Milan, Italy
- Vita-Salute, San Raffaele University, Milan, Italy
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104
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Malone JH, Chrzanowski TH, Michalak P. Sterility and gene expression in hybrid males of Xenopus laevis and X. muelleri. PLoS One 2007; 2:e781. [PMID: 17712429 PMCID: PMC1940320 DOI: 10.1371/journal.pone.0000781] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2007] [Accepted: 07/18/2007] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Reproductive isolation is a defining characteristic of populations that represent unique biological species, yet we know very little about the gene expression basis for reproductive isolation. The advent of powerful molecular biology tools provides the ability to identify genes involved in reproductive isolation and focuses attention on the molecular mechanisms that separate biological species. Herein we quantify the sterility pattern of hybrid males in African Clawed Frogs (Xenopus) and apply microarray analysis of the expression pattern found in testes to identify genes that are misexpressed in hybrid males relative to their two parental species (Xenopus laevis and X. muelleri). METHODOLOGY/PRINCIPAL FINDINGS Phenotypic characteristics of spermatogenesis in sterile male hybrids (X. laevis x X. muelleri) were examined using a novel sperm assay that allowed quantification of live, dead, and undifferentiated sperm cells, the number of motile vs. immotile sperm, and sperm morphology. Hybrids exhibited a dramatically lower abundance of mature sperm relative to the parental species. Hybrid spermatozoa were larger in size and accompanied by numerous undifferentiated sperm cells. Microarray analysis of gene expression in testes was combined with a correction for sequence divergence derived from genomic hybridizations to identify candidate genes involved in the sterility phenotype. Analysis of the transcriptome revealed a striking asymmetric pattern of misexpression. There were only about 140 genes misexpressed in hybrids compared to X. laevis but nearly 4,000 genes misexpressed in hybrids compared to X. muelleri. CONCLUSIONS/SIGNIFICANCE Our results provide an important correlation between phenotypic characteristics of sperm and gene expression in sterile hybrid males. The broad pattern of gene misexpression suggests intriguing mechanisms creating the dominance pattern of the X. laevis genome in hybrids. These findings significantly contribute to growing evidence for allelic dominance in hybrids and have implications for the mechanism of species differentiation at the transcriptome level.
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Affiliation(s)
- John H. Malone
- Department of Biology, The University of Texas at Arlington, Arlington, Texas, United States of America
| | - Thomas H. Chrzanowski
- Department of Biology, The University of Texas at Arlington, Arlington, Texas, United States of America
| | - Pawel Michalak
- Department of Biology, The University of Texas at Arlington, Arlington, Texas, United States of America
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105
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Colbourne JK, Eads BD, Shaw J, Bohuski E, Bauer DJ, Andrews J. Sampling Daphnia's expressed genes: preservation, expansion and invention of crustacean genes with reference to insect genomes. BMC Genomics 2007; 8:217. [PMID: 17612412 PMCID: PMC1940262 DOI: 10.1186/1471-2164-8-217] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Accepted: 07/06/2007] [Indexed: 11/11/2022] Open
Abstract
Background Functional and comparative studies of insect genomes have shed light on the complement of genes, which in part, account for shared morphologies, developmental programs and life-histories. Contrasting the gene inventories of insects to those of the nematodes provides insight into the genomic changes responsible for their diversification. However, nematodes have weak relationships to insects, as each belongs to separate animal phyla. A better outgroup to distinguish lineage specific novelties would include other members of Arthropoda. For example, crustaceans are close allies to the insects (together forming Pancrustacea) and their fascinating aquatic lifestyle provides an important comparison for understanding the genetic basis of adaptations to life on land versus life in water. Results This study reports on the first characterization of cDNA libraries and sequences for the model crustacean Daphnia pulex. We analyzed 1,546 ESTs of which 1,414 represent approximately 787 nuclear genes, by measuring their sequence similarities with insect and nematode proteomes. The provisional annotation of genes is supported by expression data from microarray studies described in companion papers. Loci expected to be shared between crustaceans and insects because of their mutual biological features are identified, including genes for reproduction, regulation and cellular processes. We identify genes that are likely derived within Pancrustacea or lost within the nematodes. Moreover, lineage specific gene family expansions are identified, which suggest certain biological demands associated with their ecological setting. In particular, up to seven distinct ferritin loci are found in Daphnia compared to three in most insects. Finally, a substantial fraction of the sampled gene transcripts shares no sequence similarity with those from other arthropods. Genes functioning during development and reproduction are comparatively well conserved between crustaceans and insects. By contrast, genes that were responsive to environmental conditions (metal stress) and not sex-biased included the greatest proportion of genes with no matches to insect proteomes. Conclusion This study along with associated microarray experiments are the initial steps in a coordinated effort by the Daphnia Genomics Consortium to build the necessary genomic platform needed to discover genes that account for the phenotypic diversity within the genus and to gain new insights into crustacean biology. This effort will soon include the first crustacean genome sequence.
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Affiliation(s)
- John K Colbourne
- The Center for Genomics and Bioinformatics, and Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Brian D Eads
- The Center for Genomics and Bioinformatics, and Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Joseph Shaw
- Department of Biology, Dartmouth College, Hanover, New Hampshire 03755, USA
| | - Elizabeth Bohuski
- The Center for Genomics and Bioinformatics, and Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Darren J Bauer
- Hubbard Center for Genome Studies, University of New Hampshire, Durham, New Hampshire 03824, USA
| | - Justen Andrews
- The Center for Genomics and Bioinformatics, and Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
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106
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Missirlis F, Kosmidis S, Brody T, Mavrakis M, Holmberg S, Odenwald WF, Skoulakis EMC, Rouault TA. Homeostatic mechanisms for iron storage revealed by genetic manipulations and live imaging of Drosophila ferritin. Genetics 2007; 177:89-100. [PMID: 17603097 PMCID: PMC2013694 DOI: 10.1534/genetics.107.075150] [Citation(s) in RCA: 107] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Ferritin is a symmetric, 24-subunit iron-storage complex assembled of H and L chains. It is found in bacteria, plants, and animals and in two classes of mutations in the human L-chain gene, resulting in hereditary hyperferritinemia cataract syndrome or in neuroferritinopathy. Here, we examined systemic and cellular ferritin regulation and trafficking in the model organism Drosophila melanogaster. We showed that ferritin H and L transcripts are coexpressed during embryogenesis and that both subunits are essential for embryonic development. Ferritin overexpression impaired the survival of iron-deprived flies. In vivo expression of GFP-tagged holoferritin confirmed that iron-loaded ferritin molecules traffic through the Golgi organelle and are secreted into hemolymph. A constant ratio of ferritin H and L subunits, secured via tight post-transcriptional regulation, is characteristic of the secreted ferritin in flies. Differential cellular expression, conserved post-transcriptional regulation via the iron regulatory element, and distinct subcellular localization of the ferritin subunits prior to the assembly of holoferritin are all important steps mediating iron homeostasis. Our study revealed both conserved features and insect-specific adaptations of ferritin nanocages and provides novel imaging possibilities for their in vivo characterization.
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Affiliation(s)
- Fanis Missirlis
- Neural Cell-Fate Determinants Section, National Institute of Neurological Disorders and Stroke, Bethesda, Maryland 20892, USA.
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107
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Lind MI, Missirlis F, Melefors O, Uhrigshardt H, Kirby K, Phillips JP, Söderhäll K, Rouault TA. Of two cytosolic aconitases expressed in Drosophila, only one functions as an iron-regulatory protein. J Biol Chem 2006; 281:18707-14. [PMID: 16679315 DOI: 10.1074/jbc.m603354200] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
In mammalian cells, iron homeostasis is largely regulated by post-transcriptional control of gene expression through the binding of iron-regulatory proteins (IRP1 and IRP2) to iron-responsive elements (IREs) contained in the untranslated regions of target mRNAs. IRP2 is the dominant iron sensor in mammalian cells under normoxia, but IRP1 is the more ancient protein in evolutionary terms and has an additional function as a cytosolic aconitase. The Caenorhabditis elegans genome does not contain an IRP2 homolog or identifiable IREs; its IRP1 homolog has aconitase activity but does not bind to mammalian IREs. The Drosophila genome offers an evolutionary intermediate containing two IRP1-like proteins (IRP-1A and IRP-1B) and target genes with IREs. Here, we used purified recombinant IRP-1A and IRP-1B from Drosophila melanogaster and showed that only IRP-1A can bind to IREs, although both proteins possess aconitase activity. These results were also corroborated in whole-fly homogenates from transgenic flies that overexpress IRP-1A and IRP-1B in their fat bodies. Ubiquitous and muscle-specific overexpression of IRP-1A, but not of IRP-1B, resulted in pre-adult lethality, underscoring the importance of the biochemical difference between the two proteins. Domain-swap experiments showed that multiple amino acid substitutions scattered throughout the IRP1 domains are synergistically required for conferring IRE binding activity. Our data suggest that as a first step during the evolution of the IRP/IRE system, the ancient cytosolic aconitase was duplicated in insects with one variant acquiring IRE-specific binding.
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Affiliation(s)
- Maria I Lind
- Department of Comparative Physiology, Evolutionary Biology Centre, Uppsala University, S-75236 Uppsala, Sweden.
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