Identification of a monofunctional aspartate kinase gene of Arabidopsis thaliana with spatially and temporally regulated expression.

Yoshioka, Yasushi; Kurei, Shunsuke; Machida, Yasunori

doi:10.1266/ggs.76.189

Cited by 26 publications

(15 citation statements)

References 32 publications

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“…Having multiple genes encoding this enzyme would allow more complex regulation at the level of transcription, translation, and allosteric interactions with both downstream metabolites and compounds from other plant biosynthetic pathways. Three of the A. thaliana aspartate kinase genes, At5g13280 (AK1), At5g14060 (AK2) and At3g02020 (AK3), encode monofunctional enzymes (Frankard et al, 1997;Tang et al, 1997;Yoshioka et al, 2001;Curien et al, 2007). The other two, At1g31230 (AK-HSDH1) and At4g19710 (AK-HSDH2), encode bifunctional enzymes with not only aspartate kinase, but also homoserine dehydrogenase (EC 1.1.1.3) activity (Ghislain et al, 1994;Paris et al, 2002;Rognes et al, 2002).…”

Section: Biosynthesis Of Aspartate Semialdehyde From Aspartatementioning

confidence: 99%

Aspartate-Derived Amino Acid Biosynthesis inArabidopsis thaliana

Jander

Joshi

2009

The Arabidopsis Book

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The aspartate-derived amino acid pathway in plants leads to the biosynthesis of lysine, methionine, threonine, and isoleucine. These four amino acids are essential in the diets of humans and other animals, but are present in growthlimiting quantities in some of the world's major food crops. Genetic and biochemical approaches have been used for the functional analysis of almost all Arabidopsis thaliana enzymes involved in aspartate-derived amino acid biosynthesis. The branch-point enzymes aspartate kinase, dihydrodipicolinate synthase, homoserine dehydrogenase, cystathionine gamma synthase, threonine synthase, and threonine deaminase contain well-studied sites for allosteric regulation by pathway products and other plant metabolites. In contrast, relatively little is known about the transcriptional regulation of amino acid biosynthesis and the mechanisms that are used to balance aspartatederived amino acid biosynthesis with other plant metabolic needs. The aspartate-derived amino acid pathway provides excellent examples of basic research conducted with A. thaliana that has been used to improve the nutritional quality of crop plants, in particular to increase the accumulation of lysine in maize and methionine in potatoes.

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Section: Biosynthesis Of Aspartate Semialdehyde From Aspartatementioning

confidence: 99%

Aspartate-Derived Amino Acid Biosynthesis inArabidopsis thaliana

Jander

Joshi

2009

The Arabidopsis Book

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“…1a;Galili 1995;Jander and Joshi 2010). In Arabidopsis, two bifunctional aspartate kinase-homoserine dehydrogenase (AK/HSD1 and AK/HSD2; EC1.1.1.3) isozymes are involved in initial steps of Thr, Met and Ile synthesis (Frankard et al 1997;Tang et al 1997;Yoshioka et al 2001;Rognes et al 2003;Curien et al 2009). AK/HSDs (named also AKI-HSDI and AKII-HSDII) are allosterically inhibited by Thr and stimulated by Ala, Ile, Cys, Ser and Val (Curien et al 2005).…”

Section: Introductionmentioning

confidence: 99%

“…AK/HSD1 is expressed throughout late stages of seed development, while AK/HSD2 transcription is undetectable after the onset of protein synthesis in developing seeds (Rognes et al 2003). Completely different AK-lys3 expression pattern was observed, showing more activity in old leaves and inflorescence stems (Yoshioka et al 2001). Bioinformatics analysis of public transcriptomics data clustered all AK genes in a certain ''highly coordinated gene group'' (HCG).…”

Section: Introductionmentioning

confidence: 99%

Transcriptional control of aspartate kinase expression during darkness and sugar depletion in Arabidopsis: involvement of bZIP transcription factors

Ufaz

Shukla²,

Soloveichik

et al. 2011

Planta

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Initial steps of aspartate-derived biosynthesis pathway (Asp pathway) producing Lys, Thr, Met and Ile are catalyzed by bifunctional (AK/HSD) and monofunctional (AK-lys) aspartate kinase (AK) enzymes. Here, we show that transcription of all AK genes is negatively regulated under darkness and low sugar conditions. By using yeast one-hybrid assays and complementary chromatin immunoprecipitation analyses in Arabidopsis cells, the bZIP transcription factors ABI5 and DPBF4 were identified, capable of interacting with the G-box-containing enhancer of AK/HSD1 promoter. Elevated transcript levels of DPBF4 and ABI5 under darkness and low sugar conditions coincide with the repression of AK gene expression. Overexpression of ABI5, but not DPBF4, further increases this AK transcription suppression. Concomitantly, it also increases the expression of asparagines synthetase 1 (ASN1) that shifts aspartate utilization towards asparagine formation. However, in abi5 or dpbf4 mutant and abi5, dpbf4 double mutant the repression of AK expression is maintained, indicating a functional redundancy with other bZIP-TFs. A dominant-negative version of DPBF4 fused to the SRDX repressor domain of SUPERMAN could counteract the repression and stimulate AK expression under low sugar and darkness in planta. This effect was verified by showing that DPBF4-SRDX fails to recognize the AK/HSD1 enhancer sequence in yeast one-hybrid assays, but increases heterodimmer formation with DPBF4 and ABI5, as estimated by yeast two-hybrid assays. Hence it is likely that heterodimerization with DPBF4-SRDX inhibits the binding of redundantly functioning bZIP-TFs to the promoters of AK genes and thereby releases the repressing effect. These data highlight a novel transcription control of the chloroplast aspartate pathway that operates under energy limiting conditions.

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“…This result could be the combined effect of several factors. First, among the three AK genes, the AK3 transcript is least abundant, and it is preferentially expressed in the xylem of leaves (Yoshioka et al, 2001). Second, among the three AK proteins, AK3 is most sensitive to Lys inhibition (Curien et al, 2007).…”

Section: Relative Contributions Of Different Isoforms To the Activitiesmentioning

confidence: 99%

Analysis of Loss-of-Function Mutants in Aspartate Kinase and Homoserine Dehydrogenase Genes Points to Complexity in the Regulation of Aspartate-Derived Amino Acid Contents

Clark

2015

Plant Physiol.

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ORCID IDs: 0000-0002-8396-8388 (T.J.C.); 0000-0002-3374-7376 (Y.L.).Biosynthesis of aspartate (Asp)-derived amino acids lysine (Lys), methionine (Met), threonine (Thr), and isoleucine involves monofunctional Asp kinases (AKs) and dual-functional Asp kinase-homoserine dehydrogenases (AK-HSDHs). Four-week-old loss-of-function Arabidopsis (Arabidopsis thaliana) mutants in the AK-HSDH2 gene had increased amounts of Asp and Aspderived amino acids, especially Thr, in leaves. To explore mechanisms behind this phenotype, we obtained single mutants for other AK and AK-HSDH genes, generated double mutants from ak-hsdh2 and ak mutants, and performed free and protein-bound amino acid profiling, transcript abundance, and activity assays. The increases of Asp, Lys, and Met in ak-hsdh2 were also observed in ak1-1, ak2-1, ak3-1, and ak-hsdh1-1. However, the Thr increase in ak-hsdh2 was observed in ak-hsdh1-1 but not in ak1-1, ak2-1, or ak3-1. Activity assays showed that AK2 and AK-HSDH1 are the major contributors to overall AK and HSDH activities, respectively. Pairwise correlation analysis revealed positive correlations between the amount of AK transcripts and Lys-sensitive AK activity and between the amount of AK-HSDH transcripts and both Thr-sensitive AK activity and total HSDH activity. In addition, the ratio of total AK activity to total HSDH activity negatively correlates with the ratio of Lys to the total amount of Met, Thr, and isoleucine. These data led to the hypothesis that the balance between Lys-sensitive AKs and Thrsensitive AK-HSDHs is important for maintaining the amounts and ratios of Asp-derived amino acids.

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Identification of a monofunctional aspartate kinase gene of Arabidopsis thaliana with spatially and temporally regulated expression.

Cited by 26 publications

References 32 publications

Aspartate-Derived Amino Acid Biosynthesis inArabidopsis thaliana

Aspartate-Derived Amino Acid Biosynthesis inArabidopsis thaliana

Transcriptional control of aspartate kinase expression during darkness and sugar depletion in Arabidopsis: involvement of bZIP transcription factors

Analysis of Loss-of-Function Mutants in Aspartate Kinase and Homoserine Dehydrogenase Genes Points to Complexity in the Regulation of Aspartate-Derived Amino Acid Contents

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