scholarly journals Properties of a Revertant of Escherichia coli Viable in the Presence of Spermidine Accumulation: Increase in l-Glycerol 3-Phosphate

2001 ◽  
Vol 183 (15) ◽  
pp. 4493-4498 ◽  
Author(s):  
V. Samuel Raj ◽  
Hideyuki Tomitori ◽  
Madoka Yoshida ◽  
Auayporn Apirakaramwong ◽  
Keiko Kashiwagi ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Protein Synthesis ◽  
Glycerol Kinase ◽  
High Concentration ◽  
Gene Encoding ◽  
E Coli ◽  
Inhibition Of Protein Synthesis ◽  
High Concentrations ◽  
Ribosome Modulation Factor

ABSTRACT Escherichia coli CAG2242 cells are deficient in thespeG gene encoding spermidine acetyltransferase. When these cells were cultured in the presence of 0.5 to 4 mM spermidine, their viability was greatly decreased through the inhibition of protein synthesis by overaccumulation of spermidine. When the cells were cultured with a high concentration of spermidine (4 mM), a revertant strain was obtained. We found that a 55-kDa protein, glycerol kinase, was overexpressed in the revertant and that synthesis of a ribosome modulation factor and the RNA polymerase ς38 subunit, factors important for cell viability, was increased in the revertant. Levels of l-glycerol 3-phosphate also increased in the revertant. Transformation of glpFK, which encodes a glycerol diffusion facilitator (glpF) and glycerol kinase (glpK), to E. coli CAG2242 partially prevented the cell death caused by accumulation of spermidine. It was also found that l-glycerol 3-phosphate inhibited spermidine binding to ribosomes and attenuated the inhibition of protein synthesis caused by high concentrations of spermidine. These results indicate that l-glycerol 3-phosphate reduces the binding of excess amounts of spermidine to ribosomes so that protein synthesis is recovered.

scholarly journals Postsegregational Killing Mediated by the P1 Phage “Addiction Module” phd-doc Requires the Escherichia coli Programmed Cell Death SystemmazEF

2001 ◽  
Vol 183 (6) ◽  
pp. 2046-2050 ◽  
Author(s):  
Ronen Hazan ◽  
Boaz Sat ◽  
Myriam Reches ◽  
Hanna Engelberg-Kulka
Keyword(s):  
Escherichia Coli ◽  
Cell Death ◽  
Protein Synthesis ◽  
Programmed Cell Death ◽  
Killing Effect ◽  
E Coli ◽  
Lethal Action ◽  
Free Cells ◽  
Postsegregational Killing

ABSTRACT “Addiction modules” consist of two genes; the product of the second is long lived and toxic, while the product of the first is short lived and antagonizes the lethal action of the toxin. The extrachromosomal addiction module phd-doc, located on the P1 prophage, is responsible for the postsegregational killing effect (death of plasmid-free cells). The Escherichia colichromosomal addiction module analogue, mazEF, is responsible for the induction of programmed cell death. Here we show that the postsegregational killing mediated by the P1phd-doc module depends on the presence of the E. coli mazEF system. In addition, we demonstrate that under conditions of postsegregational killing, mediated byphd-doc, protein synthesis of E. coli is inhibited. Based on our findings, we suggest the existence of a coupling between the phd-doc and mazEFsystems.

scholarly journals S-Adenosylmethionine Decarboxylase from the Archaeon Methanococcus jannaschii: Identification of a Novel Family of Pyruvoyl Enzymes

2000 ◽  
Vol 182 (23) ◽  
pp. 6667-6672 ◽  
Author(s):  
Alexander D. Kim ◽  
David E. Graham ◽  
Steven H. Seeholzer ◽  
George D. Markham
Keyword(s):  
Mass Spectrometry ◽  
Escherichia Coli ◽  
Enzymatic Activity ◽  
Complete Genome Sequence ◽  
Methanococcus Jannaschii ◽  
Phylogenetic Distribution ◽  
Gene Encoding ◽  
E Coli ◽  
Adenosylmethionine Decarboxylase ◽  
High Concentrations

ABSTRACT Polyamines are present in high concentrations in archaea, yet little is known about their synthesis, except by extrapolation from bacterial and eucaryal systems. S-Adenosylmethionine (AdoMet) decarboxylase, a pyruvoyl group-containing enzyme that is required for spermidine biosynthesis, has been previously identified in eucarya and Escherichia coli. Despite spermidine concentrations in the Methanococcales that are several times higher than in E. coli, no AdoMet decarboxylase gene was recognized in the complete genome sequence ofMethanococcus jannaschii. The gene encoding AdoMet decarboxylase in this archaeon is identified herein as a highly diverged homolog of the E. coli speD gene (less than 11% identity). The M. jannaschii enzyme has been expressed inE. coli and purified to homogeneity. Mass spectrometry showed that the enzyme is composed of two subunits of 61 and 63 residues that are derived from a common proenzyme; these proteins associate in an (αβ)2 complex. The pyruvoyl-containing subunit is less than one-half the size of that in previously reported AdoMet decarboxylases, but the holoenzyme has enzymatic activity comparable to that of other AdoMet decarboxylases. The sequence of theM. jannaschii enzyme is a prototype of a class of AdoMet decarboxylases that includes homologs in other archaea and diverse bacteria. The broad phylogenetic distribution of this group suggests that the canonical SpeD-type decarboxylase was derived from an archaeal enzyme within the gamma proteobacterial lineage. Both SpeD-type and archaeal-type enzymes have diverged widely in sequence and size from analogous eucaryal enzymes.

scholarly journals In Escherichia coli Ammonia Inhibits Cytochrome bo3 But Activates Cytochrome bd-I

Antioxidants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
Elena Forte ◽  
Sergey A. Siletsky ◽  
Vitaliy B. Borisov
Keyword(s):  
Escherichia Coli ◽  
Molecular Mechanisms ◽  
Dissociation Constants ◽  
Reductase Activity ◽  
Ammonia Concentration ◽  
High Concentration ◽  
E Coli ◽  
Cytochrome Bd ◽  
Cytochrome Bo3 ◽  
Oxygen Reductase

Interaction of two redox enzymes of Escherichia coli, cytochrome bo3 and cytochrome bd-I, with ammonium sulfate/ammonia at pH 7.0 and 8.3 was studied using high-resolution respirometry and absorption spectroscopy. At pH 7.0, the oxygen reductase activity of none of the enzymes is affected by the ligand. At pH 8.3, cytochrome bo3 is inhibited by the ligand, with 40% maximum inhibition at 100 mM (NH4)2SO4. In contrast, the activity of cytochrome bd-I at pH 8.3 increases with increasing the ligand concentration, the largest increase (140%) is observed at 100 mM (NH4)2SO4. In both cases, the effector molecule is apparently not NH4+ but NH3. The ligand induces changes in absorption spectra of both oxidized cytochromes at pH 8.3. The magnitude of these changes increases as ammonia concentration is increased, yielding apparent dissociation constants Kdapp of 24.3 ± 2.7 mM (NH4)2SO4 (4.9 ± 0.5 mM NH3) for the Soret region in cytochrome bo3, and 35.9 ± 7.1 and 24.6 ± 12.4 mM (NH4)2SO4 (7.2 ± 1.4 and 4.9 ± 2.5 mM NH3) for the Soret and visible regions, respectively, in cytochrome bd-I. Consistently, addition of (NH4)2SO4 to cells of the E. coli mutant containing cytochrome bd-I as the only terminal oxidase at pH 8.3 accelerates the O2 consumption rate, the highest one (140%) being at 27 mM (NH4)2SO4. We discuss possible molecular mechanisms and physiological significance of modulation of the enzymatic activities by ammonia present at high concentration in the intestines, a niche occupied by E. coli.

scholarly journals Lethal Action of Quinolones against a Temperature-Sensitive dnaB Replication Mutant of Escherichia coli

2006 ◽  
Vol 50 (1) ◽  
pp. 362-364 ◽  
Author(s):  
Xilin Zhao ◽  
Muhammad Malik ◽  
Nymph Chan ◽  
Alex Drlica-Wagner ◽  
Jian-Ying Wang ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Dna Replication ◽  
Nalidixic Acid ◽  
Temperature Sensitive ◽  
Wild Type ◽  
Lethal Action ◽  
Inhibition Of Protein Synthesis

ABSTRACT Inhibition of DNA replication in an Escherichia coli dnaB-22 mutant failed to block quinolone-mediated lethality. Inhibition of protein synthesis by chloramphenicol inhibited nalidixic acid lethality and, to a lesser extent, ciprofloxacin lethality in both dnaB-22 and wild-type cells. Thus, major features of quinolone-mediated lethality do not depend on ongoing replication.

The HiPIP from the acidophilic Acidithiobacillus ferrooxidans is correctly processed and translocated in Escherichia coli, in spite of the periplasm pH difference between these two micro-organisms

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1421-1431 ◽  
Author(s):  
Patrice Bruscella ◽  
Laure Cassagnaud ◽  
Jeanine Ratouchniak ◽  
Gaël Brasseur ◽  
Elisabeth Lojou ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Acidithiobacillus Ferrooxidans ◽  
Biochemical Properties ◽  
Gene Encoding ◽  
Iron Sulfur Cluster ◽  
E Coli ◽  
Iron Sulfur ◽  
Sulfur Protein ◽  
Tat System ◽  
Micro Organisms

The gene encoding a putative high-potential iron–sulfur protein (HiPIP) from the strictly acidophilic and chemolithoautotrophic Acidithiobacillus ferrooxidans ATCC 33020 has been cloned and sequenced. This potential HiPIP was overproduced in the periplasm of the neutrophile and heterotroph Escherichia coli. As shown by optical and EPR spectra and by electrochemical studies, the recombinant protein has all the biochemical properties of a HiPIP, indicating that the iron–sulfur cluster was correctly inserted. Translocation of this protein in the periplasm of E. coli was not detected in a ΔtatC mutant, indicating that it is dependent on the Tat system. The genetic organization of the iro locus in strains ATCC 23270 and ATCC 33020 is different from that found in strains Fe-1 and BRGM. Indeed, in A. ferrooxidans ATCC 33020 and ATCC 23270 (the type strain), iro was not located downstream from purA but was instead downstream from petC2, encoding cytochrome c 1 from the second A. ferrooxidans cytochrome bc 1 complex. These findings underline the genotypic heterogeneity within the A. ferrooxidans species. The results suggest that Iro transfers electrons from a cytochrome bc 1 complex to a terminal oxidase, as proposed for the HiPIP in photosynthetic bacteria.

scholarly journals Bacterial Ribonuclease MazF-Mediated Apoptosis as Potential Cancer Therapy

2021 ◽  
Author(s):  
Maryam Saffarian Abbas Zadeh ◽  
Rebecca Anne MacPherson ◽  
Guohui Huang ◽  
Hui Ding ◽  
Rhonda Reigers Powell ◽  
...  
Keyword(s):  
Cell Death ◽  
Protein Synthesis ◽  
Cell Lines ◽  
Mrna Translation ◽  
Protein Translation ◽  
Programmed Death ◽  
Inhibition Of Protein Synthesis ◽  
Cancer Agent ◽  
Cell Suicide ◽  
The Impact

Abstract Programmed cell death is a dynamic and critical mechanism of cell suicide in eukaryotes and prokaryotes. MazF is a ribonuclease protein involved in bacterial intracellular programmed death. This protein cleaves mRNAs at ACA sequences, leading to inhibition of protein synthesis and triggering cell death. Given that cancer is heterogenic and has varied susceptibility to treatment, we examined the impact of MazF proteins on the growth and viability of three cancer cell lines: MCF7, HT29, and AGS. These cell lines were transfected with ACA-less mazF mRNAs and evaluated for MazF-mediated cell death. The data illustrated that efficient MazF translation leads to a significant reduction in cell viability and is modulated by structural elements of ACA-less mazF mRNAs. In the presence of MazF, the levels of activated caspase-3 and -7 were significantly elevated in transfected cells, confirming the occurrence of apoptosis. We also quantified mRNA translation on a single-cell basis in MCF7 and AGS cell lines to examine MazF-mediated inhibition of protein synthesis. MazF expression significant decreases the levels of protein translation in the examined cell lines. This is the first report of MazF as a potential anti-cancer agent via induction of apoptosis in MCF7, AGS, and HT-29 cell lines.

Cysteine homeostasis under inhibition of protein synthesis in Escherichia coli cells

Amino Acids ◽  
2019 ◽  
Vol 51 (10-12) ◽  
pp. 1577-1592 ◽  
Author(s):  
Galina V. Smirnova ◽  
Aleksey V. Tyulenev ◽  
Kseniya V. Bezmaternykh ◽  
Nadezda G. Muzyka ◽  
Vadim Y. Ushakov ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Synthesis ◽  
Escherichia Coli Cells ◽  
Inhibition Of Protein Synthesis
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