scholarly journals Formation and Metabolism of Methylmalonyl Coenzyme A in Corynebacterium glutamicum

2009 ◽  
Vol 191 (8) ◽  
pp. 2899-2901 ◽  
Author(s):  
Laure Botella ◽  
Nic D. Lindley ◽  
Lothar Eggeling
Keyword(s):  
Escherichia Coli ◽  
Corynebacterium Glutamicum ◽  
Deletion Mutant ◽  
Coenzyme A ◽  
Growth Arrest ◽  
Dry Weight ◽  
Sequence Information ◽  
Carboxylase Activity ◽  
Genome Sequence Information ◽  
Number Of Bacteria

ABSTRACT Genome sequence information suggests that B12-dependent mutases are present in a number of bacteria, including members of the suborder Corynebacterineae like Mycobacterium tuberculosis and Corynebacterium glutamicum. We here functionally identify a methylmalonyl coenzyme A (CoA) mutase in C. glutamicum that is retained in all of the members of the suborder Corynebacterineae and is encoded by NCgl1471, NCgl1472, and NCgl1470. In addition, we observe the presence of methylmalonate in C. glutamicum, reaching concentrations of up to 757 nmol g (dry weight)−1 in propionate-grown cells, whereas in Escherichia coli no methylmalonate was detectable. As demonstrated with a mutase deletion mutant, the presence of methylmalonate in C. glutamicum is independent of mutase activity but possibly due to propionyl-CoA carboxylase activity. During growth on propionate, increased mutase activity has severe cellular consequences, resulting in growth arrest and excretion of succinate. The physiological context of the mutase present in members of the suborder Corynebacterineae is discussed.

scholarly journals Poly(3-Hydroxybutyrate) Synthesis by Recombinant Escherichia coli arcA Mutants in Microaerobiosis

2006 ◽  
Vol 72 (4) ◽  
pp. 2614-2620 ◽  
Author(s):  
Pablo I. Nikel ◽  
M. Julia Pettinari ◽  
Miguel A. Galvagno ◽  
Beatriz S. Méndez
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Specific Growth Rate ◽  
Deletion Mutant ◽  
Specific Growth ◽  
Dry Weight ◽  
Low Oxygen ◽  
Oxygen Conditions ◽  
In The Wild ◽  
Microaerobic Conditions

ABSTRACT We assessed the effects of different arcA mutations on poly(3-hydroxybutyrate) (PHB) synthesis in recombinant Escherichia coli strains carrying the pha synthesis genes from Azotobacter sp. strain FA8. The arcA mutations used were an internal deletion and the arcA2 allele, a leaky mutation for some of the characteristics of the Arc phenotype which confers high respiratory capacity. PHB synthesis was not detected in the wild-type strain in shaken flask cultures under low-oxygen conditions, while ArcA mutants gave rise to polymer accumulation of up to 24% of their cell dry weight. When grown under microaerobic conditions in a bioreactor, the arcA deletion mutant reached a PHB content of 27% ± 2%. Under the same conditions, higher biomass and PHB concentrations were observed for the strain bearing the arcA2 allele, resulting in a PHB content of 35% ± 3%. This strain grew in a simple medium at a specific growth rate of 0.69 ± 0.07 h−1, whereas the deletion mutant needed several nutritional additives and showed a specific growth rate of 0.56 ± 0.06 h−1. The results presented here suggest that arcA mutations could play a role in heterologous PHB synthesis in microaerobiosis.

scholarly journals Hibernation factors directly block ribonucleases from entering the ribosome in response to starvation

2021 ◽  
Author(s):  
Thomas Prossliner ◽  
Michael Askvad Sørensen ◽  
Kristoffer Skovbo Winther
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
16S Rrna ◽  
Deletion Mutant ◽  
Growth Arrest ◽  
Physiological Role ◽  
Wild Type ◽  
Rnase R ◽  
Initial Stage ◽  
Target Sites

Abstract Ribosome hibernation is a universal translation stress response found in bacteria as well as plant plastids. The term was coined almost two decades ago and despite recent insights including detailed cryo-EM structures, the physiological role and underlying molecular mechanism of ribosome hibernation has remained unclear. Here, we demonstrate that Escherichia coli hibernation factors RMF, HPF and RaiA (HFs) concurrently confer ribosome hibernation. In response to carbon starvation and resulting growth arrest, we observe that HFs protect ribosomes at the initial stage of starvation. Consistently, a deletion mutant lacking all three factors (ΔHF) is severely inhibited in regrowth from starvation. ΔHF cells increasingly accumulate 70S ribosomes harbouring fragmented rRNA, while rRNA in wild-type 100S dimers is intact. RNA fragmentation is observed to specifically occur at HF-associated sites in 16S rRNA of assembled 70S ribosomes. Surprisingly, degradation of the 16S rRNA 3′-end is decreased in cells lacking conserved endoribonuclease YbeY and exoribonuclease RNase R suggesting that HFs directly block these ribonucleases from accessing target sites in the ribosome.

Acanthamoeba Keratitis: Current Status and Urgent Research Priorities

2019 ◽  
Vol 26 (30) ◽  
pp. 5711-5726 ◽  
Author(s):  
Naveed Ahmed Khan ◽  
Ayaz Anwar ◽  
Ruqaiyyah Siddiqui
Keyword(s):  
Rational Design ◽  
Research Priorities ◽  
Acanthamoeba Keratitis ◽  
Current Treatment ◽  
Research Literature ◽  
Current Status ◽  
Bibliographic Databases ◽  
Sequence Information ◽  
Therapeutic Measures ◽  
Genome Sequence Information

Background:First discovered in the early 1970s, Acanthamoeba keratitis has remained a major eye infection and presents a significant threat to the public health, especially in developing countries. The aim is to present a timely review of our current understanding of the advances made in this field in a comprehensible manner and includes novel concepts and provides clear directions for immediate research priorities.Methods:We undertook a search of bibliographic databases for peer-reviewed research literature and also summarized our published results in this field.Results:The present review focuses on novel diagnostic and therapeutic strategies in details which can provide access to management and treatment of Acanthamoeba keratitis. This coupled with the recently available genome sequence information together with high throughput genomics technology and innovative approaches should stimulate interest in the rational design of preventative and therapeutic measures. Current treatment of Acanthamoeba keratitis is problematic and often leads to infection recurrence. Better understanding of diagnosis, pathogenesis, pathophysiology and therapeutic regimens, would lead to novel strategies in treatment and prophylaxis.

scholarly journals Succinyl Coenzyme A Synthetase from Escherichia coli

1967 ◽  
Vol 242 (15) ◽  
pp. 3531-3537
Author(s):  
John A. Grunau ◽  
Ernest Knight ◽  
Emily S. Hart ◽  
I.C. Gunsalus
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Succinyl Coenzyme A Synthetase

scholarly journals Mutants of Escherichia coli with Temperature-sensitive Malonyl Coenzyme A-Acyl Carrier Protein Transacylase

1974 ◽  
Vol 249 (23) ◽  
pp. 7468-7475
Author(s):  
Mark E. Harder ◽  
Ruth C. Ladenson ◽  
Steven D. Schimmel ◽  
David F. Silbert
Keyword(s):  
Escherichia Coli ◽  
Coenzyme A ◽  
Acyl Carrier Protein ◽  
Temperature Sensitive ◽  
Carrier Protein

scholarly journals Conditional Essentiality of the csrA Gene in Escherichia coli

2008 ◽  
Vol 191 (5) ◽  
pp. 1722-1724 ◽  
Author(s):  
Johan Timmermans ◽  
Laurence Van Melderen
Keyword(s):  
Escherichia Coli ◽  
Growth Inhibition ◽  
Deletion Mutant ◽  
Glycogen Synthesis ◽  
Synthetic Medium ◽  
Carbon Sources ◽  
Krebs Cycle ◽  
Physiological Processes

ABSTRACT CsrA is a global posttranscriptional regulator of numerous physiological processes, such as glycogenesis and glycolysis. Here, we show that the csrA gene of Escherichia coli is essential for growth on LB and on synthetic medium containing glycolytic carbon sources. However, csrA is not necessary for growth on synthetic medium containing pyruvate, showing that the Krebs cycle is functional in the csrA::cat deletion mutant. Deletion of the glgCAP operon in the csrA::cat mutant restored the ability to grow on LB and on synthetic medium containing glycolytic carbon sources, showing that growth inhibition is due to an excess of glycogen synthesis.

scholarly journals Perfringolysin O Expression in Clostridium perfringens Is Independent of the Upstream pfoR Gene

2002 ◽  
Vol 184 (7) ◽  
pp. 2034-2038 ◽  
Author(s):  
Milena M. Awad ◽  
Julian I. Rood
Keyword(s):  
Escherichia Coli ◽  
Homologous Recombination ◽  
Gene Product ◽  
Structural Gene ◽  
Clostridium Perfringens ◽  
Deletion Mutant ◽  
Gas Gangrene ◽  
Alpha Toxin ◽  
Clostridial Myonecrosis ◽  
Perfringolysin O

ABSTRACT The pathogenesis of Clostridium perfringens-mediated gas gangrene or clostridial myonecrosis involves the extracellular toxins alpha-toxin and perfringolysin O. Previous studies (T. Shimizu, A. Okabe, J. Minami, and H. Hayashi, Infect. Immun. 59:137-142, 1991) carried out with Escherichia coli suggested that the perfringolysin O structural gene, pfoA, was positively regulated by the product of the upstream pfoR gene. In an attempt to confirm this hypothesis in C. perfringens, a pfoR-pfoA deletion mutant was complemented with isogenic pfoA+ shuttle plasmids that varied only in their ability to encode an intact pfoR gene. No difference in the ability to produce perfringolysin O was observed for C. perfringens strains carrying these plasmids. In addition, chromosomal pfoR mutants were constructed by homologous recombination in C. perfringens. Again no difference in perfringolysin O activity was observed. Since it was not possible to alter perfringolysin O expression by mutation of pfoR, it was concluded that the pfoR gene product is unlikely to have a role in the regulation of pfoA expression in C. perfringens.

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