From Lobry de Bruyn to enzyme-catalyzed ammonia channelling: molecular studies of D-glucosamine-6P synthase

doi:10.1039/b103713g

Cited by 46 publications

(9 citation statements)

References 71 publications

(54 reference statements)

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“…However, the initial steps in this pathway collectively referred to as hexosamine pathway, have been rarely considered as drug targets. The hexosamine pathway generates UDP– N -acetyl-glucosamine (UDP–GlcNAc) and is initiated by key enzyme glucosamine-6-phosphate (GlcN6P) synthase GlmS, which synthesizes GlcN6P from L -glutamine and fructose-6-phosphate ( Figure 1A ; Milewski, 2002 ; Teplyakov et al, 2002 ). GlmS is essential unless exogenous amino sugars such as glucosamine (GlcN) are available in adequate amounts.…”

Section: Introductionmentioning

confidence: 99%

Two Small RNAs Conserved in Enterobacteriaceae Provide Intrinsic Resistance to Antibiotics Targeting the Cell Wall Biosynthesis Enzyme Glucosamine-6-Phosphate Synthase

et al. 2016

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Formation of glucosamine-6-phosphate (GlcN6P) by enzyme GlcN6P synthase (GlmS) represents the first step in bacterial cell envelope synthesis. In Escherichia coli, expression of glmS is controlled by small RNAs (sRNAs) GlmY and GlmZ. GlmZ activates the glmS mRNA by base-pairing. When not required, GlmZ is bound by adapter protein RapZ and recruited to cleavage by RNase E inactivating the sRNA. The homologous sRNA GlmY activates glmS indirectly. When present at high levels, GlmY sequesters RapZ by an RNA mimicry mechanism suppressing cleavage of GlmZ. The interplay of both sRNAs is believed to adjust GlmS synthesis to the needs of the cell, i.e., to achieve GlcN6P homeostasis. Bacilysin (tetaine) and Nva-FMDP are dipeptide antibiotics that impair cell envelope synthesis by inhibition of enzyme GlmS through covalent modification. However, although taken up efficiently, these antibiotics are less active against E. coli for reasons unknown so far. Here we show that the GlmY/GlmZ circuit provides resistance. Inhibition of GlmS causes GlcN6P deprivation leading to activation of GlmY and GlmZ, which in turn trigger glmS overexpression in a dosage-dependent manner. Mutation of glmY or glmZ disables this response and renders the bacteria highly susceptible to GlmS inhibitors. Thus, E. coli compensates inhibition of GlmS by increasing its synthesis through the GlmY/GlmZ pathway. This mechanism is also operative in Salmonella indicating that it is conserved in Enterobacteriaceae possessing these sRNAs. As GlmY apparently responds to GlcN6P, co-application of a non-metabolizable GlcN6P analog may prevent activation of the sRNAs and thereby increase the bactericidal activity of GlmS inhibitors against wild-type bacteria. Initial experiments using glucosamine-6-sulfate support this possibility. Thus, GlcN6P analogs might be considered for co-application with GlmS inhibitors in combined therapy to treat infections caused by pathogenic Enterobacteriaceae.

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Section: Introductionmentioning

confidence: 99%

Two Small RNAs Conserved in Enterobacteriaceae Provide Intrinsic Resistance to Antibiotics Targeting the Cell Wall Biosynthesis Enzyme Glucosamine-6-Phosphate Synthase

et al. 2016

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“…These enzymes play important roles in diverse biosynthetic pathways as they deliver ammonia from the side chain of glutamine to various electrophilic acceptors during the biosynthesis of cofactors, 6–8 amino acids, 9–11 amino sugars, 12 purines, 13 and pyrimidines, 14 amongst others. The tunnels serve to sequester and deliver ammonia (generated via glutamine hydrolysis in one active site) to the downstream active site.…”

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confidence: 99%

The Kinase Activity of the Helicobacter pylori Asp-tRNA^Asn/Glu-tRNA^Gln Amidotransferase Is Sensitive to Distal Mutations in Its Putative Ammonia Tunnel

et al. 2011

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The Helicobacter pylori (Hp) Asp-tRNAAsn/Glu-tRNAGln amidotransferase (AdT) plays important roles in indirect aminoacylation and translational fidelity. AdT has two active sites, in two separate subunits. Kinetic studies have suggested that interdomain communication occurs between these subunits, however this mechanism is not well understood. To explore domain-domain communication in AdT, an assay was adapted and optimized to kinetically characterize the kinase activity of Hp AdT. This assay was applied to the analysis of a series of point mutations at conserved positions throughout the putative AdT ammonia tunnel that connects the two active sites. Several mutations were identified that caused significant decreases in AdT’s kinase activity (reduced by 55–75 %). Mutations at Thr149 (37 Å distal to the GatB kinase active site) and Lys89 (located at the interface of GatA and GatB) were detrimental to AdT’s kinase activity, suggesting that these mutations have disrupted interdomain communication between the two active sites. Models of wild-type AdT, a valine mutation at Thr149, and an arginine mutation at Lys89 were subjected to molecular dynamics simulations. The comparison of wild-type, T149V and K89R AdT simulation results unmask 59 common residues that are likely involved in connecting the two active sites.

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“…We therefore turned our attention to glmY , which, in a pathway involving the RNA-binding protein RapZ and the sRNA glmZ , is responsible for increasing GlmS (glutamine–fructose 6-phosphate aminotransferase) synthesis under conditions where intracellular glucosamine 6-phosphate (GlcN6P) becomes limiting [36, 81, 82] (). GlcN6P, synthesized by GlmS from glutamine and fructose 6-phosphate (F6P), is an essential precursor of the peptidoglycan cell wall [83, 84], and so is linked to both cell envelope stress and cellular nitrogen status. Nutrient limitation led to a 4-fold decrease in glmS expression ().…”

Section: Resultsmentioning

confidence: 99%

The role of nitrogen-responsive regulators in controlling inorganic polyphosphate synthesis in Escherichia coli

et al. 2022

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Inorganic polyphosphate (polyP) is synthesized by bacteria under stressful environmental conditions and acts by a variety of mechanisms to promote cell survival. While the kinase that synthesizes polyP (PPK, encoded by the ppk gene) is well known, ppk transcription is not activated by environmental stress and little is understood about how environmental stress signals lead to polyP accumulation. Previous work has shown that the transcriptional regulators DksA, RpoN (σ54) and RpoE (σ24) positively regulate polyP production, but not ppk transcription, in Escherichia coli . In this work, we examine the role of the alternative sigma factor RpoN and nitrogen starvation stress response pathways in controlling polyP synthesis. We show that the RpoN enhancer binding proteins GlnG and GlrR impact polyP production, and uncover a new role for the nitrogen phosphotransferase regulator PtsN (EIIANtr) as a positive regulator of polyP production, acting upstream of DksA, downstream of RpoN and apparently independently of RpoE. However, neither these regulatory proteins nor common nitrogen metabolites appear to act directly on PPK, and the precise mechanism(s) by which polyP production is modulated after stress remain(s) unclear. Unexpectedly, we also found that the genes that impact polyP production vary depending on the composition of the rich media in which the cells were grown before exposure to polyP-inducing stress. These results constitute progress towards deciphering the regulatory networks driving polyP production under stress, and highlight the remarkable complexity of this regulation and its connections to a broad range of stress-sensing pathways.

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From Lobry de Bruyn to enzyme-catalyzed ammonia channelling: molecular studies of D-glucosamine-6P synthase

Cited by 46 publications

References 71 publications

Two Small RNAs Conserved in Enterobacteriaceae Provide Intrinsic Resistance to Antibiotics Targeting the Cell Wall Biosynthesis Enzyme Glucosamine-6-Phosphate Synthase

Two Small RNAs Conserved in Enterobacteriaceae Provide Intrinsic Resistance to Antibiotics Targeting the Cell Wall Biosynthesis Enzyme Glucosamine-6-Phosphate Synthase

The Kinase Activity of the Helicobacter pylori Asp-tRNA^Asn/Glu-tRNA^Gln Amidotransferase Is Sensitive to Distal Mutations in Its Putative Ammonia Tunnel

The role of nitrogen-responsive regulators in controlling inorganic polyphosphate synthesis in Escherichia coli

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From Lobry de Bruyn to enzyme-catalyzed ammonia channelling: molecular studies of D-glucosamine-6P synthase

Cited by 46 publications

References 71 publications

Two Small RNAs Conserved in Enterobacteriaceae Provide Intrinsic Resistance to Antibiotics Targeting the Cell Wall Biosynthesis Enzyme Glucosamine-6-Phosphate Synthase

Two Small RNAs Conserved in Enterobacteriaceae Provide Intrinsic Resistance to Antibiotics Targeting the Cell Wall Biosynthesis Enzyme Glucosamine-6-Phosphate Synthase

The Kinase Activity of the Helicobacter pylori Asp-tRNAAsn/Glu-tRNAGln Amidotransferase Is Sensitive to Distal Mutations in Its Putative Ammonia Tunnel

The role of nitrogen-responsive regulators in controlling inorganic polyphosphate synthesis in Escherichia coli

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The Kinase Activity of the Helicobacter pylori Asp-tRNA^Asn/Glu-tRNA^Gln Amidotransferase Is Sensitive to Distal Mutations in Its Putative Ammonia Tunnel