Insights into the central role of N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmU) in peptidoglycan metabolism and its potential as a therapeutic target

Several decades after the discovery of the first antibiotic (penicillin) microbes have evolved novel mechanisms of resistance; endangering not only our abilities to combat future bacterial pandemics but many other clinical challenges such as acquired infections during surgeries. Antimicrobial resistance (AMR) is attributed to the mismanagement and overuse of these medications and is complicated by a slower rate of the discovery of novel drugs and targets. Bacterial peptidoglycan (PG), a three-dimensional mesh of glycan units, is the foundation of the cell wall that protects bacteria against environmental insults. A significant percentage of drugs target PG, however, these have been rendered ineffective due to growing drug resistance. Identifying novel druggable targets is, therefore, imperative. Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) is one of the key building blocks in PG production, biosynthesized by the bifunctional enzyme N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmU). UDP-GlcNAc metabolism has been studied in many organisms, but it holds some distinctive features in bacteria, especially regarding the bacterial GlmU enzyme. In this review, we provide an overview of different steps in PG biogenesis, discuss the biochemistry of GlmU, and summarize the characteristic structural elements of bacterial GlmU vital to its catalytic function. Finally, we will discuss various studies on the development of GlmU inhibitors and their significance in aiding future drug discoveries.

THE ASSAY OF GALACTOKINASE AND GALACTOSE-1-PHOSPHATE URIDYL TRANSFERASE ACTIVITY IN HUMAN ERYTHROCYTES. A PRESUMED TEST FOR HETEROZYGOUS CARRIERS OF THE GALACTOSEMIC DEFECT

A simple, rapid, and direct method for measuring the activities of the galactokinase and Gal-1-P uridyl transferase enzymes in human erythrocytes is presented. The method has been applied to measurement of enzyme activities in a group of 37 presumably normal persons, 3 patients with galactosemia, 6 known heterozygous carriers of the defect, and 9 relatives of carriers. In every case the test unambiguously identified the individual's status as normal, heterozygotic carrier, or homozygously defective. Use of the test in genetic counseling and genetic epidemological studies is discussed.

Do methoxyflurane and enflurane induce hepatic drug-metabolizing enzymes?

The effect of acute anaesthetic (1,0 MAC) and chronic subanaesthetic (0,1 MAC) exposure to methoxyflurane and enflurane on the levels of several liver enzymes is reported. Methoxyflurane appears to be an enzyme-inducing agent similar to spironolactone, whereas enflurane does not appear to be an inducing agent for any of the enzymes studied.

Regulation of glutamine synthetase formation in Escherichia coli: characterization of mutants lacking the uridylyltransferase

A lambda phage (lambdaNK55) carrying the translocatable element Tn10, conferring tetracycline resistance (Tetr), has been utilized to isolate glutamine auxotrophs of Escherichia coli K-12. Such strains lack uridylyltransferase as a result of an insertion of the TN10 element in the glnD gene. The glnD::Tn10 insertion has been mapped at min 4 on the E. coli chromosome and 98% contransducible by phage P1 with dapD. A lambda transducing phage carrying the glnD gene has been identified. A glnD::Tn10 strain synthesizes highly adenylylated glutamine synthetase under all conditions of growth and fails to accumulate high levels of glutamine synthetase in response to nitrogen limitation. However, this strain, under nitrogen-limiting conditions, allows synthesis of 10 to 20 milliunits of biosynthetically active glutamine synthetase per mg of protein, which is sufficient to allow slow growth in the absence of glutamine. The GlnD phenotype in E. coli can be suppressed by the presence of mutations which increase the quantity of biosynthetically active glutamine synthetase.

Regional chromosomal localization of the human gene for galactose-1-phosphate uridyltransferase

In the progeny of somatic cell hybrids formed by fusion of human lymphocytes and Chinese hamster mutant cells, a single human chromosome A2 was selectively retained when grown in appropriate medium. Spontaneous breakage of this chromosome in different hybrid subclones led to the assignment of the gene for galactose-1-phosphate uridyltransferase to the centromeric region of this chromosome (2q11 leads to 2q14). This gene is shown to be syntenic to the previously mapped genes for acid phosphatase 1 and malate dehydrogenase 1.