Deletion of Glutamine Synthetase Gene Disrupts the Survivability and Infectivity of Leishmania donovani

Abstract

Glutamine synthetase (GS) is one of the most important metabolic enzymes which catalyzes ligation of glutamate and ammonia to form glutamine. Previous studies from our lab had revealed significant differences in parasite and host GS enzyme which warranted us to further work on its relevance in parasite. To analyze glutamine synthetase function in Leishmania, we generated GS overexpressors and knockout mutants and evaluated their ability to grow in vitro in monocyte differentiated macrophage and in vivo by infections in BALB/c mice. GS knocked out strain showed significant growth retardation with delayed cell cycle progression and morphological alteration. Null mutants exhibited attenuated infectivity both in in vitro and in vivo experiments and the effect was reverted back when infected with GS complemented parasites. This indicated that the alterations in phenotype observed were indeed due to GS knockout. GS knockout also made the parasite increasingly sensitive to Miltefosine. Detailed investigation of mode of parasite death upon Miltefosine treatment by dual staining with Annexin-V conjugated FITC and propidium iodide, pointed towards apoptotic or necrotic mode of cell death. This is the first report to confirm that GS is essential for the survivability and infectivity of Leishmania donovani, and can be exploited as a potential drug-target.

Cross-linking mass spectrometry reveals structural insights of the glutamine synthetase from Leishmania braziliensis

“…The potential of GS from Leishmania sp as therapeutic target was also evidenced by knock-out experiments indicating the dependence of parasite proliferation and infectivity on external supply of glutamine. (31) Herein, we provide LbGS structural investigation identifying the active site, important interfaces, and unique structural features from LbGS. All these information allow investigation for new drugs.…”

Transcriptome profile of halofuginone resistant and sensitive strains of Eimeria tenella

“…In Leishmania , GS can be exploited as a potential drug target ( Cruzat et al, 2018 ). In Leishmania , it can be exploited as a potential drug target ( Kumar et al, 2021 ). Based on our data, the expression level of programmed cell death protein is upregulated, the result is consistent with our previous work ( Figure 1 ).…”

An Intrinsic Alkalization Circuit Turns on mntP Riboswitch under Manganese Stress in Escherichia coli

“…Thus, for the first time, our study provides a rationale for the existence of two Gls proteins in E. coli ( 21 , 29 ). A recent report suggests that deletion of glutamine synthetase (GS) in Leishmania donovani affects its viability ( 30 ). Mycobacterium tuberculosis GS has also been considered as a potential therapeutic target to inhibit its growth ( 31 ).…”