The conversion of leucine to α-ketoisocaproic acid and its metabolic consequences for Escherichia coli K12

1976 ◽  
Vol 22 (7) ◽  
pp. 922-928 ◽  
Author(s):  
E. B. Newman ◽  
T. Adley ◽  
J. Fraser ◽  
R. Potter ◽  
V. Kapoor
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Amino Acid ◽  
Nitrogen Source ◽  
Sole Nitrogen Source ◽  
Escherichia Coli K12 ◽  
Nitrogen Donor

The amino acid L-leucine serves as a good auxiliary nitrogen source for Escherichia coli K12, and in so doing is converted to alpha-ketoisocaproic acid which is excreted into the medium.L-Leucine does not serve as sole nitrogen source. Cells incubated with L-leucine as sole nitrogen source do not grow, although they do metabolize leucine, and accumulate ketoisocaproic acid in the medium.Where glycine is the only other nitrogen source, the presence of L-leucine greatly increases the growth rate even at concentrations so low that its contribution as nitrogen donor is unlikely to be important.

scholarly journals Multi-step resistance to Chloramphenicol in RC-stringent Escherichia coli K12—its effect on the induction of RNA synthesis by antibiotics under amino acid starvation

1965 ◽  
Vol 6 (2) ◽  
pp. 304-309 ◽  
Author(s):  
E. C. R. Reeve ◽  
J. O. Bishop
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Resistant Strain ◽  
Parent Strain ◽  
Rna Synthesis ◽  
Amino Acid Starvation ◽  
Sensitive Strain ◽  
Escherichia Coli K12 ◽  
High Doses

A multi-step Chloramphenicol (CM)-resistant derivative of an RC-stringent strain of Escherichia coli auxotrophic for threonine and leucine was resistant also to Aureomycin (AM) and Puromycin (PM). All three antibiotics released the repression of RNA synthesis due to amino acid starvation in the CM-sensitive parent strain, their relative activities being about 1:10:100 for AM: CM: PM. High doses of AM and CM failed to induce RNA synthesis. The CM-resistant strain required greater concentrations of each antibiotic than the sensitive strain to induce the same level of RNA synthesis, and appeared to be about one hundred times, ten times and five times more resistant to CM, AM and PM, respectively, than the sensitive strain.

Utilization of chymotrypsin as a sole carbon and (or) nitrogen source by Escherichia coli

1992 ◽  
Vol 38 (4) ◽  
pp. 290-295 ◽  
Author(s):  
Arthur S. Brecher ◽  
Timothy A. Moehlman ◽  
William D. Hann
Keyword(s):  
Escherichia Coli ◽  
Carbon Source ◽  
Nitrogen Source ◽  
Degradation Products ◽  
Defined Medium ◽  
Host Protein ◽  
Mammalian Host ◽  
Sole Nitrogen Source ◽  
E Coli ◽  
Nitrogen Nutrients

α-Chymotrypsin serves as a sole carbon source, sole nitrogen source, and as sole carbon plus nitrogen source for wild-type Escherichia coli in a totally defined medium. Hence, a mammalian host for E. coli may supply the necessary carbon and nitrogen nutrients for the microorganism. Growth is most rapid when chymotrypsin is a sole nitrogen source,and least rapid with chymotrypsin as a carbon source. The approximate doubling times for E. coli utilizing chymotrypsin as a nitrogen source, carbon plus nitrogen source, and carbon source are 1.6, 4.6, and 11.3 h, respectively. The activity of the residual enzyme in the culture supernates falls off asymptotically over the course of time, as followed by cleavage of glutaryl-L-phenylalanine-p-nitroanilide. Chymotrypsin hydrolyzes succinyl-L-ala-L-ala-L-ala-p-nitroanilide, the elastase substrate, to some extent. Peptidases do not appear to be secreted that hydrolyze such model substrates as benzoyl-DL-arginine-p-nitroanilide, the tryptic and cathepsin B substrate, L-leucine-p-nitroanilide, the leucine aminopeptidase substrate, or L-lysine-p-nitroanilide, the aminopeptidase B substrate. Growth of E. coli is generally directly related to the loss of chymotryptic activity in the medium. Hence, autolysis of chymotrypsin, i.e., self-degradation, is an important factor for the availability of degradation products of the enzyme to the bacterium for growth purposes. Accordingly, the degradation of a host protein by autolysis presents an opportunity for E. coli to survive during periods of host nutritional crisis by utilization of the degradation peptides that are produced during autolysis. Key words: chymotrypsin, Escherichia coli, growth, nutrition, peptide source.

The use of glycine as nitrogen source by Escherichia coli K12

1976 ◽  
Vol 421 (1) ◽  
pp. 97-105 ◽  
Author(s):  
E NEWMAN ◽  
G BATIST ◽  
J FRASER ◽  
S ISENBERG ◽  
P WEYMAN ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Source ◽  
Escherichia Coli K12

scholarly journals DksA Is Required for Growth Phase-Dependent Regulation, Growth Rate-Dependent Control, and Stringent Control of fis Expression in Escherichia coli

2006 ◽  
Vol 188 (16) ◽  
pp. 5775-5782 ◽  
Author(s):  
Prabhat Mallik ◽  
Brian J. Paul ◽  
Steven T. Rutherford ◽  
Richard L. Gourse ◽  
Robert Osuna
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Amino Acid ◽  
Rna Polymerase ◽  
Growth Phase ◽  
Stationary Growth ◽  
Rate Dependent ◽  
Transcription In Vitro ◽  
State Growth

ABSTRACT DksA is a critical transcription factor in Escherichia coli that binds to RNA polymerase and potentiates control of rRNA promoters and certain amino acid promoters. Given the kinetic similarities between rRNA promoters and the fis promoter (Pfis), we investigated the possibility that DksA might also control transcription from Pfis. We show that the absence of dksA extends transcription from Pfis well into the late logarithmic and stationary growth phases, demonstrating the importance of DksA for growth phase-dependent regulation of fis. We also show that transcription from Pfis increases with steady-state growth rate and that dksA is absolutely required for this regulation. In addition, both DksA and ppGpp are required for inhibition of Pfis promoter activity following amino acid starvation, and these factors act directly and synergistically to negatively control Pfis transcription in vitro. DksA decreases the half-life of the intrinsically short-lived fis promoter-RNA polymerase complex and increases its sensitivity to the concentration of CTP, the predominant initiating nucleotide triphosphate for this promoter. This work extends our understanding of the multiple factors controlling fis expression and demonstrates the generality of the DksA requirement for regulation of kinetically similar promoters.

scholarly journals Enzymic synthesis of N-acetyl-l-phenylalanine in Escherichia coli K12

1971 ◽  
Vol 124 (5) ◽  
pp. 905-913 ◽  
Author(s):  
R. V. Krishna ◽  
P. R. Krishnaswamy ◽  
D. Rajagopal Rao
Keyword(s):  
Escherichia Coli ◽  
Amino Acids ◽  
Amino Acid ◽  
Substrate Specificity ◽  
Acetyl Coa ◽  
Ph Optimum ◽  
E Coli ◽  
Enzymic Synthesis ◽  
Escherichia Coli K12

1. Cell-free extracts of Escherichia coli K12 catalyse the synthesis of N-acetyl-l-phenylalanine from acetyl-CoA and l-phenylalanine. 2. The acetyl-CoA–l-phenylalanine α-N-acetyltransferase was purified 160-fold from cell-free extracts. 3. The enzyme has a pH optimum of 8 and catalyses the acetylation of l-phenylalanine. Other l-amino acids such as histidine and alanine are acetylated at slower rates. 4. A transacylase was also purified from E. coli extracts and its substrate specificity studied. 5. The properties of both these enzymes were compared with those of other known amino acid acetyltransferases and transacylases.

Gene cloning and characterization of thiourocanate hydratase from Burkholderia sp. HME13

2019 ◽  
Vol 167 (3) ◽  
pp. 333-341
Author(s):  
Hisashi Muramatsu ◽  
Haruna Miyaoku ◽  
Syuya Kurita ◽  
Hidenori Matsuo ◽  
Takehiro Kashiwagi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Amino Acid ◽  
Amino Acid Sequence ◽  
Crude Extract ◽  
Maximum Activity ◽  
Luria Bertani ◽  
Sole Nitrogen Source ◽  
Gene Encoding ◽  
Gene Cloning And Characterization

Abstract A novel enzyme, thiourocanate hydratase, which catalyses the conversion of thiourocanic acid to 3-(5-oxo-2-thioxoimidazolidin-4-yl) propionic acid, was isolated from the ergothioneine-utilizing strain, Burkholderia sp. HME13. When the HME13 cells were cultured in medium containing ergothioneine as the sole nitrogen source, thiourocanate-metabolizing activity was detected in the crude extract from the cells. However, activity was not detected in the crude extract from HME13 cells that were cultured in Luria-Bertani medium. The gene encoding thiourocanate hydratase was cloned and expressed in Escherichia coli, and the recombinant enzyme was purified to homogeneity. The enzyme showed maximum activity at pH 7.5 and 55°C and was stable between pH 5.0 and 10.5, and at temperatures up to 45°C. The Km and Vmax values of thiourocanate hydratase towards thiourocanic acid were 30 μM and 7.1 μmol/min/mg, respectively. The enzyme was strongly inhibited by CuCl2 and HgCl2. The amino acid sequence of the enzyme showed 46% identity to urocanase from Pseudomonas putida, but thiourocanate hydratase had no urocanase activity.

scholarly journals Functional Characterization of Alanine Racemase fromSchizosaccharomyces pombe: a Eucaryotic Counterpart to Bacterial Alanine Racemase

2001 ◽  
Vol 183 (7) ◽  
pp. 2226-2233 ◽  
Author(s):  
Takuma Uo ◽  
Tohru Yoshimura ◽  
Naotaka Tanaka ◽  
Kaoru Takegawa ◽  
Nobuyoshi Esaki
Keyword(s):  
Escherichia Coli ◽  
Nitrogen Source ◽  
Functional Characterization ◽  
Open Reading Frame ◽  
Alanine Racemase ◽  
Sole Nitrogen Source ◽  
Recombinant Yeast ◽  
Reading Frame ◽  
Putative Protein

ABSTRACT Schizosaccharomyces pombe has an open reading frame, which we named alr1 +, encoding a putative protein similar to bacterial alanine racemase. We cloned thealr1 + gene in Escherichia coli and purified the gene product (Alr1p), with an M rof 41,590, to homogeneity. Alr1p contains pyridoxal 5′-phosphate as a coenzyme and catalyzes the racemization of alanine with apparentKm and V max values as follows: for l-alanine, 5.0 mM and 670 μmol/min/mg, respectively, and for d-alanine, 2.4 mM and 350 μmol/min/mg, respectively. The enzyme is almost specific to alanine, but l-serine and l-2-aminobutyrate are racemized slowly at rates 3.7 and 0.37% of that ofl-alanine, respectively. S. pombe usesd-alanine as a sole nitrogen source, but deletion of thealr1 + gene resulted in retarded growth on the same medium. This indicates that S. pombe has catabolic pathways for both enantiomers of alanine and that the pathway forl-alanine coupled with racemization plays a major role in the catabolism of d-alanine. Saccharomyces cerevisiae differs markedly from S. pombe: S. cerevisiae uses l-alanine but notd-alanine as a sole nitrogen source. Moreover,d-alanine is toxic to S. cerevisiae. However, heterologous expression of the alr1 + gene enabled S. cerevisiae to grow efficiently ond-alanine as a sole nitrogen source. The recombinant yeast was relieved from the toxicity of d-alanine.

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