Cloning and sequence analysis of a cDNA for barley ferredoxin-dependent glutamate synthase and molecular analysis of photorespiratory mutants deficient in the enzyme

Ávila, Concepción; Márquez, Antonio J.; Pajuelo, Purificación; Cannell, M. E.; Wallsgrove, R. M.; Forde, Brian G.

doi:10.1007/bf00198209

Cited by 41 publications

(29 citation statements)

References 41 publications

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“…It is surprising that two Fd-GOGAT genes were discovered in Arabidopsis, because single genes for Fd-GOGAT have been reported for plants with much larger genomes. These include maize, tobacco, barley, spinach, and Scots pine (Sakakibara et al, 1991;Zehnacker et al, 1992;Avila et al, 1993;Nalbantoglu et al, 1994;García-Gutiérrez et al, 1995). Because the Arabidopsis GLU2 gene was only discovered after sequencing 13 independent cDNAs (only one of which was GLU2), it is likely that other species contain a second gene for Fd-GOGAT that may have been missed in other cDNA screens because of low expression levels.…”

Section: Discussionmentioning

confidence: 99%

Arabidopsis gls Mutants and Distinct Fd-GOGAT Genes: Implications for Photorespiration and Primary Nitrogen Assimilation

et al. 1998

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Ferredoxin-dependent glutamate synthase (Fd-GOGAT) plays a major role in photorespiration in Arabidopsis, as has been determined by the characterization of mutants deficient in Fd-GOGAT enzyme activity ( gls ). Despite genetic evidence for a single Fd-GOGAT locus and gene, we discovered that Arabidopsis contains two expressed genes for Fd-GOGAT ( GLU1 and GLU2 ). Physical and genetic mapping of the gls1 locus and GLU genes indicates that GLU1 is linked to the gls1 locus, whereas GLU2 maps to a different chromosome. Contrasting patterns of GLU1 and GLU2 expression explain why a mutation in only one of the two genes for Fd-GOGAT leads to a photorespiratory phenotype in the gls1 mutants. GLU1 mRNA was expressed at the highest levels in leaves, and its mRNA levels were specifically induced by light or sucrose. In contrast, GLU2 mRNA was expressed at lower constitutive levels in leaves and preferentially accumulated in roots. Although these results suggest a major role for GLU1 in photorespiration, the sucrose induction of GLU1 mRNA in leaves also suggests a role in primary nitrogen assimilation. This possibility is supported by the finding that chlorophyll levels of a gls mutant are significantly lower than those of the wild type when grown under conditions that suppress photorespiration. Both the mutant analysis and gene regulation studies suggest that GLU1 plays a major role in photorespiration and also plays a role in primary nitrogen assimilation in leaves, whereas the GLU2 gene may play a major role in primary nitrogen assimilation in roots. INTRODUCTIONGlutamate synthase (glutamine-oxoglutarate aminotransferase or GOGAT) is a key enzyme involved in the assimilation of inorganic nitrogen in higher plants ( Lea and Miflin, 1974;Keys et al., 1978;Miflin and Lea, 1980;Stewart et al., 1980). Functioning coordinately with glutamine synthetase (GS; EC 6.3.1.2), the GS/GOGAT pair provides the primary port of entry for nitrogen in whole-plant metabolism. Inorganic nitrogen, in the form of ammonia, is assimilated via this glutamate synthase cycle into the organic nitrogen compounds glutamine and glutamate, which are the nitrogen donors in essentially all biosynthetic reactions involving nitrogen (e.g., amino acids, nucleic acids, and chlorophyll). Primary nitrogen assimilation requires cofactors, reducing equivalents, and carbon skeletons generated during photosynthesis. Thus, in most plants, assimilation of inorganic nitrogen into organic form occurs predominantly in leaf chloroplasts where these components are readily available (Sechley et al., 1992). In plant species that are able to efficiently transport photosynthate to roots, such as maize and temperate legumes, nitrogen assimilation also occurs at high rates in root plastids (Oaks, 1992).In addition to its major role in primary nitrogen assimilation, the GS/GOGAT cycle also plays a crucial role in reassimilating the large amount of ammonia released during photorespiration (Somerville and Ogren, 1980;Kendall et al., 1986). The amount of ammonia released during pho...

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Section: Discussionmentioning

confidence: 99%

Arabidopsis gls Mutants and Distinct Fd-GOGAT Genes: Implications for Photorespiration and Primary Nitrogen Assimilation

et al. 1998

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“…In the same region of this protein motif, three conserved cysteines potentially involved in an iron-sulphur cluster in alfalfa NADH-GOGAT [23] are also present. In a recent work, Avila et al [5] have identified a putative glutamine-amidotransferase domain in the N-terminal region of barley Fd-GOGAT, which is homologous to the corresponding domain of thepur F-type amidotransferases. Taken together, the above data suggest the existence of two functional parts in the same polypeptide chain, the N-terminal glutamine-amidotransferase and the C-terminal electron transfer domains that should be closely related during enzyme catalysis.…”

Section: Northern Blot Analysis Of Fd-gogat Messagementioning

confidence: 99%

“…Based on the different physicochemical, immunological and regulatory properties of both enzymes in a number of higher plants, it is assumed that they are distinct proteins [27,42]. This assumption has been recently confirmed by the isolation and characterization of different cDNA clones encoding Fd-dependent [ 5,38,49] and NADH-dependent [23 ] glutamate synthases.…”

Section: Introductionmentioning

confidence: 99%

Expression of ferredoxin-dependent glutamate synthase in dark-grown pine seedlings

et al. 1995

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Pine seedlings are able to accumulate chlorophylls and develop green plastids in a light-independent manner. In this work, we have characterized ferredoxin-dependent glutamate synthase (EC 1.4.7.1; Fd-GOGAT), a key enzyme in nitrogen interconversion during this process. Fd-GOGAT has been purified about 170-fold from cotyledons of maritime pine (Pinus pinaster). As occurs in angiosperms, the native enzyme is a single polypeptide with an apparent molecular mass of 163-168 kDa that is confined to the chloroplast stroma. Polyclonal antibodies generated against the purified enzyme were used to immunoscreen a lambda gt11 expression library from Scots pine (Pinus sylvestris) seedlings and partial cDNA clones were isolated and characterized. The clone with the longest cDNA insert (pGOP44) contained the codification for the C-terminal (550 amino acids) of the pine Fd-GOGAT polypeptide. Immunological cross-reactivity and comparative amino sequence analysis revealed that Fd-GOGAT is a well conserved protein in higher plants. Western blot analyses showed that protein was expressed in chloroplast-containing pine tissues and this expression pattern was not affected by exogenously supplied nitrogen. Fd-GOGAT mRNA, polypeptide and enzyme activity accumulated in substantial amounts in dark-grown pine seedlings. The presence of a functional Fd-GOGAT may be important to provide the required glutamate for the biosynthesis of nitrogen compounds during chloroplast biogenesis in the dark.

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“…GOGAT genes genomic sequences have been reported for maize [21], tobacco [22], Arabidopsis [23] and barley [24] and partial sequences were also reported in bread wheat [25]. Recently, NADH and Fd-GOGAT gene structures, genomic sequences, gene localization, and involvement in GPC control have been reported in durum wheat [26,27].…”

Section: Introductionmentioning

confidence: 99%

Allelic Variants of Glutamine Synthetase and Glutamate Synthase Genes in a Collection of Durum Wheat and Association with Grain Protein Content

et al. 2017

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Abstract:Wheat is one of the most important crops grown worldwide. Despite the fact that it accounts for only 5% of the global wheat production, durum wheat (Triticum turgidum L. subsp. durum) is a commercially important tetraploid wheat species, which originated and diversified in the Mediterranean basin. In this work, the candidate gene approach has been applied in a collection of durum wheat genotypes; allelic variants of genes glutamine synthetase (GS2) and glutamate synthase (GOGAT) were screened and correlated with grain protein content (GPC). Natural populations and collections of germplasms are quite suitable for this approach, as molecular polymorphisms close to a locus with evident phenotypic effects may be closely associated with their character, providing a better physical resolution than genetic mapping using ad hoc constituted populations. A number of allelic variants were detected both for GS2 and GOGAT genes, and regression analysis demonstrated that some variations are positively and significantly related to the GPC effect. Additionally, these genes map into homoeologous chromosome groups 2 and 3, where several authors have localized important quantitative trait loci (QTLs) for GPC. The information outlined in this work could be useful in breeding and marker-assisted selection programs.

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Cloning and sequence analysis of a cDNA for barley ferredoxin-dependent glutamate synthase and molecular analysis of photorespiratory mutants deficient in the enzyme

Cited by 41 publications

References 41 publications

Arabidopsis gls Mutants and Distinct Fd-GOGAT Genes: Implications for Photorespiration and Primary Nitrogen Assimilation

Arabidopsis gls Mutants and Distinct Fd-GOGAT Genes: Implications for Photorespiration and Primary Nitrogen Assimilation

Expression of ferredoxin-dependent glutamate synthase in dark-grown pine seedlings

Allelic Variants of Glutamine Synthetase and Glutamate Synthase Genes in a Collection of Durum Wheat and Association with Grain Protein Content

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