alanine synthesis
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2022 ◽  
Author(s):  
Zheng Zhang ◽  
Penghui He ◽  
Shiying Hu ◽  
Yanqing Yu ◽  
Xiaoting Wang ◽  
...  

Abstract Objective: The production of some bio-chemicals affected by the cell growth. This study aimed at promoting the cell growth by overexpressing the synthesis of peptidoglycans tetrapeptide tail components to improve poly-γ-glutamic acid (γ-PGA) production. Results: L-alanine, D-alanine and D-alanyl-D-alanine are primary precursors for the synthesis of peptidoglycans. The addition of L-alanine and D-alanine significantly increased both the cell growth and production of γ-PGA. Then, several genes encoding key enzymes for L/D-alanine and D-alanyl-D-alanine biosynthesis were overexpressed respectively, including ald (encoding alanine dehydrogenase), dal (encoding alanine racemase) and ddl (encoding D-alanine ligase). The results showed that the overexpression of genes ald , dal and ddl increased the production of γ-PGA by 19.72%, 15.91% and 60.90%, and increased the microbial biomass by 15.58%, 18.34% and 49.85%, respectively. Moreover, we demonstrated that the overexpression of genes ald , dal and ddl increased γ-PGA production mainly by enhancing cell growth rather than providing more precursors. Conclusions: This work illustrated the importance of the L/D-alanine and D-alanyl-D-alanine synthesis to the cell growth and the high yield of γ-PGA, and provided an effective strategy for producing γ-PGA .


2019 ◽  
Author(s):  
Mariana López-Sámano ◽  
Luis Fernando Lozano-Aguirre Beltrán ◽  
Rosina Sánchez-Thomas ◽  
Araceli Dávalos ◽  
Tomás Villaseñor ◽  
...  

Abstractβ-alanine synthesis in bacteria occurs by the decarboxylation of L-aspartate as part of the pantothenate synthesis pathway. In the other two domains of life we find different pathways for β-alanine formation, such as sources from spermine in plants, uracil in yeast and by transamination reactions in insects and mammals. There are also promiscuous decarboxylases that can decarboxylate aspartate. Several bioinformatics studies about the conservation of pantothenate synthesis pathway performed on bacteria, archaea and eukaryotes, have shown a partial conservation of the pathway. As a part of our work, we performed an analysis of the prevalence of reported β-alanine synthesis pathways in 204 genomes of alpha-proteobacteria, with a focus on theRhizobialesorder. The aim of this work was to determine the enzyme or pathway used to synthetize β-alanine inRhizobium etliCFN42. Our bioinformatics analysis showed that this strain encodes the pyrimidine degradation pathway in its genome. We obtained a β-alanine synthase (amaB)mutant that was a β-alanine auxotroph. Complementation with the cloned gene restored the wild type phenotype. Biochemical analysis confirmed that the recombinant AmaB catalyzed the formation of β-alanine from 3-Ureidopropionic acidin vitro. Here we show a different way in bacteria to produce this essential metabolite.ImportanceSince the pioneer studies of Cronan (1980) on β-alanine synthesis inE. coli, it has been assumed that the decarboxilation of aspartate by the L-aspartate-α-decarboxylase it’s the main enzymatic reaction for β-alanine synthesis in bacteria. Forty years later, while we were studying the pantothenic acid synthesis in rhizobia, we demonstrate that a numerous and diverse group of bacteria classified as α-proteobacteria synthesize β-alaninede novousing β-alanine synthase, the last enzyme from the reductive pathway for uracil degradation.Additionally, there is a growing interest in β-amino acid due to its remarkable pharmaceuticals properties as hypoglycemic, antiketogenic and anti-fungal agents.


eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Alam García-Heredia ◽  
Amol Arunrao Pohane ◽  
Emily S Melzer ◽  
Caleb R Carr ◽  
Taylor J Fiolek ◽  
...  

Rod-shaped mycobacteria expand from their poles, yet d-amino acid probes label cell wall peptidoglycan in this genus at both the poles and sidewall. We sought to clarify the metabolic fates of these probes. Monopeptide incorporation was decreased by antibiotics that block peptidoglycan synthesis or l,d-transpeptidation and in an l,d-transpeptidase mutant. Dipeptides complemented defects in d-alanine synthesis or ligation and were present in lipid-linked peptidoglycan precursors. Characterizing probe uptake pathways allowed us to localize peptidoglycan metabolism with precision: monopeptide-marked l,d-transpeptidase remodeling and dipeptide-marked synthesis were coincident with mycomembrane metabolism at the poles, septum and sidewall. Fluorescent pencillin-marked d,d-transpeptidation around the cell perimeter further suggested that the mycobacterial sidewall is a site of cell wall assembly. While polar peptidoglycan synthesis was associated with cell elongation, sidewall synthesis responded to cell wall damage. Peptidoglycan editing along the sidewall may support cell wall robustness in pole-growing mycobacteria.


2015 ◽  
Vol 52 (12) ◽  
pp. 1002-1008 ◽  
Author(s):  
Jihen Mahfoudh ◽  
Slim Salhi ◽  
Christelle Delaite ◽  
Souhir Abid ◽  
Rachid El Gharbi

2014 ◽  
Vol 52 (1) ◽  
pp. 56-63 ◽  
Author(s):  
Marwa Abbes ◽  
Slim Salhi ◽  
Lénaïg Lefevre ◽  
Christelle Delaite ◽  
Souhir Abid ◽  
...  

2014 ◽  
Vol 4 (1) ◽  
pp. 23-26
Author(s):  
G. Ye. Avetisova ◽  
L. H. Melkonyan ◽  
A. Kh. Chakhalyan ◽  
S. Gh. Keleshyan ◽  
A. S. Saghyan

2013 ◽  
Vol 34 (3) ◽  
pp. 460-466 ◽  
Author(s):  
Andreas W Fries ◽  
Sherry Dadsetan ◽  
Susanne Keiding ◽  
Lasse K Bak ◽  
Arne Schousboe ◽  
...  

Ammonia has a key role in the development of hepatic encephalopathy (HE). In the brain, glutamine synthetase (GS) rapidly converts blood-borne ammonia into glutamine which in high concentrations may cause mitochondrial dysfunction and osmolytic brain edema. In astrocyte-neuron cocultures and brains of healthy rats, inhibition of GS by methionine sulfoximine (MSO) reduced glutamine synthesis and increased alanine synthesis. Here, we investigate effects of MSO on brain and interorgan ammonia metabolism in sham and bile duct ligated (BDL) rats. Concentrations of glutamine, glutamate, alanine, and aspartate and incorporation of 15NH4+ into these amino acids in brain, liver, muscle, kidney, and plasma were similar in sham and BDL rats treated with saline. Methionine sulfoximine reduced glutamine concentrations in liver, kidney, and plasma but not in brain and muscle; MSO reduced incorporation of 15NH4+ into glutamine in all tissues. It did not affect alanine concentrations in any of the tissues but plasma alanine concentration increased; incorporation of 15NH4+ into alanine was increased in brain in sham and BDL rats and in kidney in sham rats. It inhibited GS in all tissues examined but only in brain was an increased incorporation of 15N-ammonia into alanine observed. Liver and kidney were important for metabolizing blood-borne ammonia.


Amino Acids ◽  
2013 ◽  
Vol 45 (2) ◽  
pp. 301-307 ◽  
Author(s):  
A. René ◽  
N. Vanthuyne ◽  
J. Martinez ◽  
F. Cavelier
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