Staphylococcus aureus grown in anaerobic conditions exhibit elevated glutamine biosynthesis and biofilm units

2020 ◽  
Author(s):  
V.G. Yugandhar ◽  
M. M. Sunita ◽  
Santhosh Kumar Pasupuleti ◽  
S Subbarayadu ◽  
Abhijit Chaudhary ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Glutamine Synthetase ◽  
Brain Heart Infusion ◽  
Redox Status ◽  
Multidrug Resistant ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Chromosomal Dna ◽  
Resistant Strains ◽  
High Degree

The enormous spread of Staphylococcus aureus infections through biofilms is a major concern in hospital-acquired infections. Biofilm formation by S. aureus on any surface is facilitated by adjusting its redox status. This organism is a facultative anaerobe shifts more towards reductive conditions by enhancing nitrogen metabolism where Glutamine synthesis plays a key role. Glutamine is synthesized by Glutamine synthetase (GS) encoded by the glnA gene was PCR amplified from the chromosomal DNA of Staphylococcus aureus, sequenced (HQ329146.1) and cloned; the pure recombinant GS exhibited KM11.06±0.05mM for Glutamate and 2.4±0.03mM for ATP. The glnA gene sequence showed high degree variability with the human counterpart while it was highly conserved in bacteria. Structural analysis revealed the GS structure of S. aureus showed close homology with other Gram-positive bacteria and exhibited a high degree of variation with E .coli GS. In the present study, we have observed the increased presence of glutamine synthetase activity in multidrug-resistant strains of Staphylococcus aureus with elevated biofilm units grown in brain heart infusion broth among them methicillin-resistant strains of S. aureus LMV3-5 showed higher biofilm units. All these results explain the important role of glutamine biosynthesis with elevated biofilm units in the pathogenesis of S. aureus.

scholarly journals Contribution of a Thickened Cell Wall and Its Glutamine Nonamidated Component to the Vancomycin Resistance Expressed by Staphylococcus aureus Mu50

2000 ◽  
Vol 44 (9) ◽  
pp. 2276-2285 ◽  
Author(s):  
Longzhu Cui ◽  
Hiroko Murakami ◽  
Kyoko Kuwahara-Arai ◽  
Hideaki Hanaki ◽  
Keiichi Hiramatsu
Keyword(s):  
Staphylococcus Aureus ◽  
Cell Wall ◽  
Glutamine Synthetase ◽  
Glucose Utilization ◽  
Vancomycin Resistance ◽  
Cross Linking ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Peptidoglycan Synthesis ◽  
Different Levels

ABSTRACT Staphylococcus aureus Mu50, which has reduced susceptibility to vancomycin, has a remarkably thickened cell wall with an increased proportion of glutamine nonamidated muropeptides. In addition, Mu50 had enhanced glutamine synthetase andl-glutamine d-fructose-6-phosphate aminotransferase activities, which are involved in the cell-wall peptidoglycan synthesis pathway. Furthermore, significantly increased levels of incorporation of 14C-labeledd-glucose into the cell wall was observed in Mu50. Unlike afemC mutant S. aureus strain, increased levels of production of nonamidated muropeptides in Mu50 was not caused by lower levels of glutamine synthetase activity but was considered to be due to the glutamine depletion caused by increased glucose utilization by the cell to biosynthesize increased amounts of peptidoglycan. After the cells were allowed to synthesize cell wall in the absence or presence of glucose and glutamine, cells with different cell-wall thicknesses and with cell walls with different levels of cross-linking were prepared, and susceptibility testing of these cells demonstrated a strong correlation between the cell-wall thickness and the degree of vancomycin resistance. Affinity trapping of vancomycin molecules by the cell wall and clogging of the outer layers of peptidoglycan by bound vancomycin molecules were considered to be the mechanism of vancomycin resistance of Mu50. The reduced cross-linking and the increased affinity of binding to vancomycin of the Mu50 cell wall presumably caused by the increased proportion of nonamidated muropeptides may also contribute to the resistance to some extent.

The salt tolerance ofRhizobiumstrains and lentil genotypes and the effect of salinity on aspects of symbiotic N-fixation

1983 ◽  
Vol 100 (1) ◽  
pp. 81-86 ◽  
Author(s):  
R. Rai
Keyword(s):  
Salt Stress ◽  
Salt Tolerance ◽  
Glutamine Synthetase ◽  
Tricarboxylic Acid ◽  
N Fixation ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Salt Tolerant ◽  
Antibiotic Resistant ◽  
Resistant Strains

SUMMARYThreeRhizobiumstrains and four lentil genotypes were more salt tolerant under different salt stress conditions. Saline-resistant strains were more antibiotic resistant and showed higher relative rates of oxidation of carbohydrate and tricarboxylic acid intermediates. Under salt stress, significant interactions between strains and genotypes resulted in a differential response of N2·fixation and glutamine synthetase activity.

Respective effects of glucose and glutamine on the glutamine synthetase activity of human skin fibroblasts

1991 ◽  
Vol 102 (2) ◽  
Author(s):  
Th�ophile Soni ◽  
Claire Wolfrom ◽  
Samia Guerroui ◽  
Nicole Raynaud ◽  
Jos�phine Poggi ◽  
...  
Keyword(s):  
Glutamine Synthetase ◽  
Human Skin ◽  
Skin Fibroblasts ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Human Skin Fibroblasts

Control of nitrogen assimilation in Stichococcus bacillaris by growth conditions

1987 ◽  
Vol 65 (3) ◽  
pp. 432-437 ◽  
Author(s):  
Iftikhar Ahmad ◽  
Johan A. Hellebust
Keyword(s):  
Glutamine Synthetase ◽  
Nitrogen Assimilation ◽  
Continuous Light ◽  
Synthetase Activity ◽  
Glutamine Synthetase Activity ◽  
Dark Cycle ◽  
Continuous Darkness ◽  
Cell Carbon ◽  
Stichococcus Bacillaris ◽  
Mixotrophic Conditions

Stichococcus bacillaris Naeg. (Chlorophyceae) grown on a 12 h light: 12 h dark cycle divides synchronously under photoautotrophic conditions and essentially nonsynchronously under mixotrophic conditions. Photoassimilation of carbon under photoautotrophic conditions was followed by a decline in cell carbon content during the dark period, whereas under mixotrophic conditions cell carbon increased throughout the light–dark cycle. The rates of nitrogen assimilation by cultures grown on either nitrate or ammonium declined sharply during the dark, and these declines were most pronounced under photoautotrophic conditions. Photoautotrophic cells synthesized glutamine synthetase and NADPH – glutamate dehydrogenase (GDH) exclusively in the light, whereas in mixotrophic cells about 20% of the total synthesis of these enzymes during one light–dark cycle occurred in the dark. NADH–GDH was synthesized almost continuously over the entire light–dark cycle. In the dark, both under photoautotrophic and mixotrophic conditions, the alga contained more than 50% of glutamine synthetase in an inactive form, which was reactivated in vitro in the presence of mercaptoethanol and in vivo after returning the cultures to the light. The thermal stability of glutamine synthetase activity was less in light-harvested cells than in dark-harvested cells. The inactivation of glutamine synthetase did not occur in cultures growing either heterotrophically in continuous darkness or photoautotrophically in continuous light. This enzyme appears to be under thiol control only in cells grown under alternating light–dark conditions, irrespective of whether this light regime results in synchronous cell division or not.

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