An estimate of the extent of deamination of <scp>L</scp>-serine in auxotrophs of <i>Escherichia coli</i> K-12

Ramotar, Dindial; Newman, E. B.

doi:10.1139/m86-155

Cited by 9 publications

(7 citation statements)

References 13 publications

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“…Availability of S‐adenosylmethionine (and other methyl donors) depends on the availability of l ‐serine, the ultimate donor of C1 units (Newman and Magasanik, 1963). If, as it seems (Ramotar and Newman, 1986), L‐SD regulates the concentration of serine in the cell, one might expect that the triple mutant functions with a very different internal l ‐serine concentration than its parent, which might in turn change the availability of methyl donors.…”

Section: Resultsmentioning

confidence: 99%

“…That SdaA actually does deaminate exogenously provided l ‐serine in vivo is shown by the fact that a serA sdaA auxotroph requires 50% less l ‐serine than a serA strain which produces SdaA (Ramotar and Newman, 1986). SdaA and TdcG have been directly characterized in vitro as specific L‐SDs virtually devoid of activity against threonine (Burman et al ., 2004; Cicchillo et al ., 2004).…”

Section: Discussionmentioning

confidence: 99%

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Deficiency in l‐serine deaminase results in abnormal growth and cell division of Escherichia coli K‐12

Zhang

Newman

2008

Molecular Microbiology

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SummaryThe loss of the ability to deaminate L-serine severely impairs growth and cell division in Escherichia coli K-12. A strain from which the three genes (sdaA, sdaB, tdcG) coding for this organism's three L-serine deaminases had been deleted grows well in glucose minimal medium but, on subculture into minimal medium with glucose and casamino acids, it makes very large, abnormally shaped cells, many of which lyse. When inoculated into Luria-Bertani (LB) broth with or without glucose, it makes very long filaments. Provision of S-adenosylmethionine restores cell division in LB broth with glucose, and repairs much of the difficulty in growth in medium with casamino acids. We suggest that replication of E. coli is regulated by methylation, that an unusually high intracellular L-serine concentration, in the presence of other amino acids, starves the cell for Sadenosylmethionine and that it is the absence of S-adenosylmethionine and/or of C1-tetrahydrofolate derivatives that prevents normal cell division.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Deficiency in l‐serine deaminase results in abnormal growth and cell division of Escherichia coli K‐12

Zhang

Newman

2008

Molecular Microbiology

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“…The serAP1P2 plasmid showed the regulation expected for serA on the basis of earlier work (Pizer, 1963;Ramotar and Newman, 1986;Lin et al, 1990). Its high transcription in glucose-minimal medium was cut to about 60% by growth in the presence of 100 mg ml-1 leucine (19 425 versus 10 875; Table 2), and it was transcribed very little in LB (1550).…”

Section: Expression Of Lacz From Mutated Sera Promotersmentioning

confidence: 54%

Structure of the Lrp‐regulated serA promoter of Escherichia coli K‐12

Yang

Lin

Newman³

2002

Molecular Microbiology

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SummaryExpression of the Escherichia coli serA gene is activated in vivo by the product of the lrp gene, leucineresponsive regulatory protein (Lrp), an effect partially reversed by L-leucine. We show here that serA is transcribed from two promoters, P1 45 bp upstream of the translation start site, and P2 92 bp further upstream. Lrp binds to a long AT-rich sequence from -158 to -82 from the start of the coding region, i.e. upstream of P1 and overlapping P2. It activates transcription from P1 and represses expression from P2. A second regulator, cAMP/CRP, activates P2, an effect that is largely inhibited by Lrp, such that catabolite repressor protein (Crp) and Lrp are rival activators of serA transcription.

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“…The experiments of Seigele and Hu were done in the presence of a number of amino acids, among them serine at 40 g/ml. This is a low concentration compared to the 500 g/ml needed to saturate a culture of a serine-requiring mutant, and even a serine auxotroph degrades serine extensively (24). Because serine is the first amino acid used from a mixture of amino acids (23), we think that serine disappears rapidly in their experiments and that these experiments were done by accident at a critical level of serine which varies just enough from cell to cell so that some cells have enough serine to inhibit the arabinose promoter and some do not.…”

Section: Discussionmentioning

confidence: 99%

Comparison of the Sensitivities of Two Escherichia coli Genes to In Vivo Variation of Lrp Concentration

Chen

Newman

1998

J Bacteriol

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Transcription of the Escherichia coli genesserA and gltBDF depends on the leucine-responsive regulatory protein, Lrp, and is very much decreased in an lrp mutant. By the use of an Lrp-deficient host and the lrp gene cloned under a plasmid-borne arabinose pBAD promoter, we varied the amount of Lrp present in the cell and showed that both genes were transcribed in proportion to the amount of Lrp synthesized. The affinity of serA for Lrp was four to five times greater than the affinity of gltD. Overproduction of Lrp was lethal to the cell.

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An estimate of the extent of deamination of L-serine in auxotrophs of Escherichia coli K-12

Cited by 9 publications

References 13 publications

Deficiency in l‐serine deaminase results in abnormal growth and cell division of Escherichia coli K‐12

Deficiency in l‐serine deaminase results in abnormal growth and cell division of Escherichia coli K‐12

Structure of the Lrp‐regulated serA promoter of Escherichia coli K‐12

Comparison of the Sensitivities of Two Escherichia coli Genes to In Vivo Variation of Lrp Concentration

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