Concerted Feedback Inhibition of the Aspartokinase of<i>Rhodospirillum tenue</i>by Threonine and Methionine: a Novel Pattern

Robert-Géro, Malka; Borgne, L. Le; Cohen, Georges N.

doi:10.1128/jb.112.1.251-258.1972

Cited by 16 publications

(2 citation statements)

References 37 publications

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“…Lys‐sensitive AKIII from E. coli is inhibited in synergy by Lys and Leu [22]. AKIII from Bacillus subtilis [23,24] and AK from Rhodopseudomonas [25,26], display synergistic inhibition by Lys and Thr. Synergistic inhibition requires the existence in these enzymes of two sites, one for each coinhibitor.…”

Section: Discussionmentioning

confidence: 99%

Allosteric monofunctional aspartate kinases from Arabidopsis

et al. 2006

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Plant monofunctional aspartate kinase is unique among all aspartate kinases, showing synergistic inhibition by lysine and S‐adenosyl‐l‐methionine (SAM). The Arabidopsis genome contains three genes for monofunctional aspartate kinases. We show that aspartate kinase 2 and aspartate kinase 3 are inhibited only by lysine, and that aspartate kinase 1 is inhibited in a synergistic manner by lysine and SAM. In the absence of SAM, aspartate kinase 1 displayed low apparent affinity for lysine compared to aspartate kinase 2 and aspartate kinase 3. In the presence of SAM, the apparent affinity of aspartate kinase 1 for lysine increased considerably, with K0.5 values for lysine inhibition similar to those of aspartate kinase 2 and aspartate kinase 3. For all three enzymes, the inhibition resulted from an increase in the apparent Km values for the substrates ATP and aspartate. The mechanism of aspartate kinase 1 synergistic inhibition was characterized. Inhibition by lysine alone was fast, whereas synergistic inhibition by lysine plus SAM was very slow. SAM by itself had no effect on the enzyme activity, in accordance with equilibrium binding analyses indicating that SAM binding to aspartate kinase 1 requires prior binding of lysine. The three‐dimensional structure of the aspartate kinase 1–Lys–SAM complex has been solved [Mas‐Droux C, Curien G, Robert‐Genthon M, Laurencin M, Ferrer JL & Dumas R (2006) Plant Cell18, 1681–1692]. Taken together, the data suggest that, upon binding to the inactive aspartate kinase 1–Lys complex, SAM promotes a slow conformational transition leading to formation of a stable aspartate kinase 1–Lys–SAM complex. The increase in aspartate kinase 1 apparent affinity for lysine in the presence of SAM thus results from the displacement of the unfavorable equilibrium between aspartate kinase 1 and aspartate kinase 1–Lys towards the inactive form.

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Section: Discussionmentioning

confidence: 99%

Allosteric monofunctional aspartate kinases from Arabidopsis

et al. 2006

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“…In the examined plants the most usual type is an effect of both threonine and lysine (Bryan et al 1970, Wong andDennis 1973a, b), except for the threonine-sensitive enzyme from peas (Aarnes and Rognes 1974). In the case of wheat and duckweed (Wong and Dennis 1973a, b) and cucumber (Figure 1 A) concerted feedback inhibition by threonine and lysine is indicated, a regulation mechanism which is widespread among bacteria (Robert-Gero et al 1972).…”

Section: Resultsmentioning

confidence: 91%

Aspartate Kinase from Some Higher Plants and Algae

Aarnes

1974

Physiologia Plantarum

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Regulation of aspartate kinase activity was examined in some higher plant seedlings (Helianthus annuus, Raphanus sativus, Cucumis sativus, Sinapis alba),, a green (Chlorella pyrenoidosa),, and a blue-green alga (Anacystis nidulans). In Cucumis sativus a concerted feedback regulation by L-lysine and L-threonine was indicated. In all the other species examined, aspartate kinase was inhibited by both L-lysine and L-threonine and it depended upon the species which of them was the strongest inhibitor. Only slight effects of L-leucine, L-isoleucine and L-valine were observed, except in the Sinapis alba enzyme.

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Identification and expression of a cDNA from Daucus carota encoding a bifunctional aspartokinase-homoserine dehydrogenase

Weisemann

Matthews

1993

Plant Mol Biol

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Aspartokinase (EC 2.7.2.4) and homoserine dehydrogenase (EC 1.1.1.3) catalyze steps in the pathway for the synthesis of lysine, threonine, and methionine from aspartate. Homoserine dehydrogenase was purified from carrot (Daucus carota L.) cell cultures and portions of it were subjected to amino acid sequencing. Oligonucleotides deduced from the amino acid sequences were used as primers in a polymerase chain reaction to amplify a DNA fragment using DNA derived from carrot cell culture mRNA as template. The amplification product was radiolabelled and used as a probe to identify cDNA clones from libraries derived from carrot cell culture and root RNA. Two overlapping clones were isolated. Together the cDNA clones delineate a 3089 bp long sequence encompassing an open reading frame encoding 921 amino acids, including the mature protein and a long chloroplast transit peptide. The deduced amino acid sequence has high homology with the Escherichia coli proteins aspartokinase I-homoserine dehydrogenase I and aspartokinase II-homoserine dehydrogenase II. Like the E. coli genes the isolated carrot cDNA appears to encode a bifunctional aspartokinase-homoserine dehydrogenase enzyme.

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Concerted Feedback Inhibition of the Aspartokinase ofRhodospirillum tenueby Threonine and Methionine: a Novel Pattern

Cited by 16 publications

References 37 publications

Allosteric monofunctional aspartate kinases from Arabidopsis

Allosteric monofunctional aspartate kinases from Arabidopsis

Aspartate Kinase from Some Higher Plants and Algae

Identification and expression of a cDNA from Daucus carota encoding a bifunctional aspartokinase-homoserine dehydrogenase

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