Studies on the biosynthesis of porphyrin and bacteriochlorophyll by <i>Rhodopseudomonas spheroides</i>. 3. The effect of threonine on the biosynthesis of homoserine and methionine

Gibson, Kenneth D.; Neuberger, A.; Tait, G. H.

doi:10.1042/bj0840483

Cited by 34 publications

(12 citation statements)

References 15 publications

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“…This type of response was named "concerted inhibition" by Datta & Gest (65). spheroides (68) and to be inhi bited only by threonine in Rhodospirillum rub rum (67). In contrast to the concerted inhibi tion of aspartokinase from Rps.…”

Section: Biosynthetic Regulationmentioning

confidence: 98%

Regulation of Enzyme Activity

Atkinson¹

1966

Annu. Rev. Biochem.

605

155

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Modulation of enzyme behavior by variation in the concentration of specific metabolites has not been previously reviewed in this series. For the first review of a ten-year-old field, the admonition of the editors to attempt an appraisal of the present status of the field rather than an annotated bibliography seems particularly apt. This article is limited, with few ex ceptions, to discussion of in vitro systems, where the effect of a metabolite modifier on a specified enzyme can be demonstrated directly. Two essentially separate, although functionally related, subjects are reviewed: the kinetics of regulatory enzymes, with models and concepts that have been proposed, and the possible metabolic significance to be attributed to the properties of such enzymes.Parts of the area covered here have been discussed, usually along with enzyme repression, in several reviews or summary articles (1-6). Enzyme activity in an intact cell must obviously be affected by many factors besides metabolite modulation. In vivo effects of spatial, permeability, and transport relationships, and of changes in such parameters as pH, temperature, ionic strength, and the concentrations of individual ions have been reviewed by Grisolia (7).

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Section: Biosynthetic Regulationmentioning

confidence: 98%

Regulation of Enzyme Activity

Atkinson¹

1966

Annu. Rev. Biochem.

605

155

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“…In wild type R. sphaeroides, limitation of methionine can be achieved by the addition of threonine, which inhibits its formation at the stage of homoserine dehydrogenase (26). We therefore studied the effect of threonine upon the accumulation of tetrapyrroles by the wild type and TSPO1 cells.…”

Section: Accumulation Of Porphyrin Intermediates In Wildmentioning

confidence: 99%

A Novel Mechanism for the Regulation of Photosynthesis Gene Expression by the TspO Outer Membrane Protein of Rhodobacter sphaeroides 2.4.1

Yeliseev

Kaplan

1999

Journal of Biological Chemistry

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A bacterial homolog of the mammalian mitochondrial benzodiazepine receptor, the tryptophan-rich sensory protein (TspO) has been previously demonstrated to negatively affect the transcriptional expression of several photosynthesis genes of Rhodobacter sphaeroides. To identify components of the signal transduction pathway from the outer membrane-localized TspO to the DNA-active transcription factor(s), we examined the involvement of TspO in the regulation of tetrapyrrole metabolism in R. sphaeroides. By analyzing the tetrapyrrole pigments accumulated by resting cell suspensions of R. sphaeroides, we demonstrated that TspO negatively regulates the activity of coproporphyrinogen III oxidase in this bacterium. hemN, encoding one of the isoenzymes of coproporphyrinogen III oxidase of R. sphaeroides, provided in trans to the wild type strain, produced a TSPO1 mutant phenotype by abolishing the negative effect of TspO on the transcription of the photosynthesis genes, crtI and puc. It is proposed that TspO, by regulating the exit of certain tetrapyrrole intermediates of the heme/bacteriochlorophyll biosynthetic pathways in R. sphaeroides in response to the availability of molecular oxygen, causes the accumulation of a biosynthetic intermediate that serves as a corepressor for both specific pigment gene transcription and the puc operon. The relationship between the bacterial TspO and the mitochondrial peripheral benzodiazepine receptor is discussed.

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“…Homoserine dehydrogenase II is specifically repressed by methionine and is not subject to end product inhibition. In several other microorganisms only one homoserine dehydrogenase was found, which is inhibited by one or more end products and in some cases activated by other terminal products (Nara et al, 1961;Gibson, Neuberger and Tait, 1962;Karassevitch and De Robichon-Szulmajster, 1963;Datta and Gest, 1965;Miyajima, Otsuka and Shiio, 1968;Robert-Gero, Poiret and Cohen, 1970). A homoserine dehydrogenase insensitive to feedback inhibition and not repressed by the end products has been reported in Neurospora crassa (Jenkins and Woodward, 1970).…”

Section: Introductionmentioning

confidence: 99%

Regulation of homoserine dehydrogenase inAzotobacter species

Sala‐Trepat¹,

Robert-Géro²,

Borgne³

1972

Antonie van Leeuwenhoek

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SALA-TREPAT, J. M., ROBERT-GERo, M. and LE BORGNE, L. 1972. Regulation of homoserine dehydrogenase in Azotobacter species. Antonie van Leeuwenhoek: 38: 493-503.The regulation of homoserine dehydrogenase activity was studied in nine Azotobacter strains belonging to five different species. In all the species the enzyme is subject to feedback inhibition by L-threonine and L-isoleucine, the first being much more active as inhibitor. The inhibition by L-threonine is noncompetitive with respect to NADPH and of mixed type with respect to aspartate-f3-semialdehyde; the inhibition by L-isoleucine is noncompetitive with respect to both substrates. The synthesis of homoserine dehydrogenase in Azotobacter chroococcum I.P. is somewhat repressed by 1 mM L-methionine and 5 mM L-isoleucine. In all the strains examined either NADPH or NADH can serve as cofactors for this activity, though the ratio of activity with the two pyridine nucleotides (NADPH/NADH) shows higher values (3.3-3.8) in the species macrocytogenes and insignis than in the chroococcum, beijerhTckii and vinelandii group (1.5-1.6). The pattern of control of this enzyme in the genus Azotobacter is discussed in relation to other bacterial homoserine dehydrogenases.

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Studies on the biosynthesis of porphyrin and bacteriochlorophyll by Rhodopseudomonas spheroides. 3. The effect of threonine on the biosynthesis of homoserine and methionine

Cited by 34 publications

References 15 publications

Regulation of Enzyme Activity

Regulation of Enzyme Activity

A Novel Mechanism for the Regulation of Photosynthesis Gene Expression by the TspO Outer Membrane Protein of Rhodobacter sphaeroides 2.4.1

Regulation of homoserine dehydrogenase inAzotobacter species

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