Sequence of the GLT1 gene from Saccharomyces cerevisiae reveals the domain structure of yeast glutamate synthase

Filetici, Patrizia; Martegani, Marco Paolo; Valenzuela, Lourdes; González, Alicia; Ballario, Paola

doi:10.1002/(sici)1097-0061(199610)12:13<1359::aid-yea3>3.0.co;2-5

Cited by 27 publications

(16 citation statements)

References 33 publications

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“…The mitochondrion contains many [Fe-S] cluster-containing proteins including enzymes of the respiratory chain (eg, complex I and III), ferrochelatase, and enzymes of the citric acid cycle such as aconitase and succinate dehydrogenase. There are also cytosolic [Fe-S] clustercontaining proteins including the well-known human IRP1 ( Figure 2) but also yeast glutamate synthase (Glt1p) 21 and isopropylmalate isomerase (Leu1p). 22 There is also an example of a human nuclear [Fe-S] protein, human endonuclease III homolog 1 (hNTH1), which is involved in base excision repair and has homologs in the yeast and mouse.…”

Section: The Mitochondrion Is a Major Site Of [Fe-s] Synthesismentioning

confidence: 99%

Iron trafficking in the mitochondrion: novel pathways revealed by disease

Napier

Ponka

Richardson

2005

Blood

252

201

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It is well known that iron (Fe) is trans- IntroductionSince its discovery, the mitochondrion has been known as an essential and dynamic component of cellular biochemistry. The complexity of the mitochondrion has been gradually revealed by the study of a variety of genetic diseases associated with its function. Thus far, it is clear that Fe plays a crucial role in many facets of mitochondrial metabolism and the consequences of disruption to these pathways are catastrophic. Therefore, it would seem clear that the mitochondrion, a site of dynamically active electron transport and redox activity, would possess sufficient measures for the safe trafficking and metabolism of Fe. However, until recently, knowledge of the Fe metabolism of the mitochondrion has been largely confined to the heme synthesis pathway (for review, see Ponka 1 ), and very little was understood concerning the trafficking and storage of Fe in this organelle.The recent discovery of a plethora of mitochondrial proteins believed to be involved in Fe metabolism has resulted in a marked increase of research in this field. Key proteins identified include frataxin, ATP-binding cassette protein B7 (ABCB7), and the more recently discovered mitochondrial ferritin. These discoveries have provided evidence to support the hypothesis that the mitochondrion is a distinct compartment of Fe metabolism. However, despite these new data, the Fe trafficking pathways within the mitochondrion remain unclear, and in this review we will attempt to analyze and integrate the most recent findings in this intriguing field. Iron transport, storage, and homeostatic regulationBefore discussing the most recent results regarding mitochondrial Fe metabolism, we will first provide a brief overview of the well-characterized molecular pathways of cellular Fe trafficking and utilization. Iron is transported within the serum bound to the Fe-binding protein, transferrin (Tf), 2-4 that binds to the transferrin receptor 1 (TfR1; Figure 1). The receptor binds 2 molecules of Fe-loaded Tf, 5 resulting in receptor-mediated endocytosis of the Tf-TfR1 complex (for reviews, see Morgan, 2 Richardson and Ponka, 3 and Hentze et al 4 ). A reduction in endosomal pH 2,3,6 mediates the release of Fe from Tf. 2,7 A protein known as the natural resistance-associated macrophage protein 2 (Nramp2) 8 was subsequently demonstrated to be the long sought-after exporter of Fe ϩ2 from endosomes. [9][10][11] This molecule is now known as divalent metal ion transporter 1 (DMT1) but has also been denoted as the divalent cation transporter 1 (DCT1) or solute carrier family 11a member 2 (Slc11a2).Within the cytosol, Fe can be stored in a large multimeric protein known as ferritin. 12 The storage of Fe in this molecule protects the cells from the damaging effects of free Fe and also keeps it sequestered in a bioavailable form. Since Fe is such an important but potentially toxic metal, its uptake, storage, and mobilization pathways are tightly regulated. This homeostatic control mechanism is largely controlled by RNA-bi...

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Section: The Mitochondrion Is a Major Site Of [Fe-s] Synthesismentioning

confidence: 99%

Iron trafficking in the mitochondrion: novel pathways revealed by disease

Napier

Ponka

Richardson

2005

Blood

252

201

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“…PCC 7120 has been sequenced, showing that glsF encoding Fd-glutamate synthase is the unique glutamate synthase gene (Martin-Figueroa et al 2000), and to date genes for NADH-glutamate synthase have not been found in this cyanobacterium. In contrast, only NADH-glutamate synthase has been detected in fungi and yeast such as Neurospora crassa (Hummelt and Mora 1980), Saccharomyces cerevisiae (Cogoni et al 1995;Filetici et al 1996) and Kluyveromyces lactis (Romero et al 2000), where it appears to be present as a monomeric protein of high molecular weight.…”

Section: Occurrence Of Glutamate Synthasesmentioning

confidence: 99%

“…NADH-glutamate synthase GLT contains the conserved sequences of gltB and gltD found in prokaryotic NADPH-glutamate synthase genes, and a b subunit-like polypeptide has been fused at the C-terminus of the a subunit-like polypeptide. NADH-glutamate synthase has also been shown to be a monomeric polypeptide in fungi (Hummlet and Mora 1980), yeasts (Cogoni et al 1995;Filetici et al 1996;Romero et al 2000) and insects (Hirayama et al 1998). A region linking heterodimeric ab subunit-like polypeptides of NADH-glutamate synthase contains hydrophilic and charged amino acids (histidine, lysine, arginine, glutamate) (Gregerson et al 1993;Goto et al 1998).…”

Section: Occurrence Of Glutamate Synthasesmentioning

confidence: 99%

Glutamate synthase: structural, mechanistic and regulatory properties, and role in the amino acid metabolism

2005

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Ammonium ion assimilation constitutes a central metabolic pathway in many organisms, and glutamate synthase, in concert with glutamine synthetase (GS, EC 6.3.1.2), plays the primary role of ammonium ion incorporation into glutamine and glutamate. Glutamate synthase occurs in three forms that can be distinguished based on whether they use NADPH (NADPH-GOGAT, EC 1.4.1.13), NADH (NADH-GOGAT, EC 1.4.1.14) or reduced ferredoxin (Fd-GOGAT, EC 1.4.7.1) as the electron donor for the (two-electron) conversion of L-glutamine plus 2-oxoglutarate to L-glutamate. The distribution of these three forms of glutamate synthase in different tissues is quite specific to the organism in question. Gene structures have been determined for Fd-, NADH- and NADPH-dependent glutamate synthases from different organisms, as shown by searches in nucleic acid sequence data banks. Fd-glutamate synthase contains two electron-carrying prosthetic groups, the redox properties of which are discussed. A description of the ferredoxin binding by Fd-glutamate synthase is also presented. In plants, including nitrogen-fixing legumes, Fd-glutamate synthase and NADH-glutamate synthase supply glutamate during the nitrogen assimilation and translocation. The biological functions of Fd-glutamate synthase and NADH-glutamate synthase, which show a highly tissue-specific distribution pattern, are tightly related to the regulation by the light and metabolite sensing systems. Analysis of mutants and transgenic studies have provided insights into the primary individual functions of Fd-glutamate synthase and NADH-glutamate synthase. These studies also provided evidence that glutamate dehydrogenase (NADH-GDH, EC 1.4.1.2) does not represent a significant alternate route for glutamate formation in plants. Taken together, biochemical analysis and genetic and molecular data imply that Fd-glutamate synthase incorporates photorespiratory and non-photorespiratory ammonium and provides nitrogen for transport to maintain nitrogen status in plants. Fd-glutamate synthase also plays a role that is redundant, in several important aspects, to that played by NADH-glutamate synthase in ammonium assimilation and nitrogen transport.

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“…These variable effects on development of fungal species might be due more to the alternatives of biochemical signaling pathway(s) than to the structural differences of Gln synthetase in these fungi. This is supported by the fact that Gln synthetase genes are highly conserved in their amino acid sequences in several plant pathogenic fungi and play a crucial role in ammonium assimilation and Glu biosynthesis in prokaryotes and eukaryotes, including fungi (Filetici et al, 1996;Stephenson et al, 1997). To confirm the role of inhibition of appressorium formation on the disease protection, glufosinate ammonium was washed 24 h prior to inoculation and the remaining chemicals were completely removed 1 h prior to inoculation.…”

Section: Glufosinate Ammonium Inhibits Prepenetration Morphogenesismentioning

confidence: 99%

Glufosinate Ammonium-Induced Pathogen Inhibition and Defense Responses Culminate in Disease Protection in bar-Transgenic Rice

Ahn

2007

Plant Physiol.

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Glufosinate ammonium diminished developments of rice (Oryza sativa) blast and brown leaf spot in 35S:bar-transgenic rice. Pre-and postinoculation treatments of this herbicide reduced disease development. Glufosinate ammonium specifically impeded appressorium formation of the pathogens Magnaporthe grisea and Cochliobolus miyabeanus on hydrophobic surface and on transgenic rice. In contrast, conidial germination remained unaffected. Glufosinate ammonium diminished mycelial growth of two pathogens; however, this inhibitory effect was attenuated in malnutrition conditions. Glufosinate ammonium caused slight chlorosis and diminished chlorophyll content; however, these alterations were almost completely restored in transgenic rice within 7 d. Glufosinate ammonium triggered transcriptions of PATHOGENESIS-RELATED (PR) genes and hydrogen peroxide accumulation in transgenic rice and PR1 transcription in Arabidopsis (Arabidopsis thaliana) wild-type ecotype Columbia harboring 35S:bar construct. All transgenic Arabidopsis showed robust hydrogen peroxide accumulation by glufosinate ammonium. This herbicide also induced PR1 transcription in etr1 and jar1 expressing bar; however, no expression was observed in NahG and npr1. Fungal infection did not alter transcriptions of PR genes and hydrogen peroxide accumulation induced by glufosinate ammonium. Infiltration of glufosinate ammonium did not affect appressorium formation of M. grisea in vivo but inhibited blast disease development. Hydrogen peroxide scavengers nullified blast protection and transcriptions of PR genes by glufosinate ammonium; however, they did not affect brown leaf spot progression. In sum, both direct inhibition of pathogen infection and activation of defense systems were responsible for disease protection in bar-transgenic rice.

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Sequence of the GLT1 gene from Saccharomyces cerevisiae reveals the domain structure of yeast glutamate synthase

Cited by 27 publications

References 33 publications

Iron trafficking in the mitochondrion: novel pathways revealed by disease

Iron trafficking in the mitochondrion: novel pathways revealed by disease

Glutamate synthase: structural, mechanistic and regulatory properties, and role in the amino acid metabolism

Glufosinate Ammonium-Induced Pathogen Inhibition and Defense Responses Culminate in Disease Protection in bar-Transgenic Rice

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