Disease relevance of pilT

• Queuine deficiency was determined by an exchange assay using [8-3H]guanine and tRNA:guanine transglycosylase from Escherichia coli [1].
• In the absence of the putative transglycosylase, internalization of the phage genome is significantly delayed during infection [2].
• The transglycosylase inhibitors vancomycin, teicoplanin, and moenomycin induced synthesis of the VanX D,D-dipeptidase in a VanA-type Enterococcus faecalis harboring transposon Tn1546 [3].
• The putative catalytic residue in the family 3 lytic transglycosylase from Pseudomonas aeruginosa, Glu162 as identified by sequence alignment to the homologous enzyme from Escherichia coli, was replaced with both Ala and Asp by site-directed mutagenesis [4].
• Major peptidoglycan transglycosylase activities, which synthesize uncross-linked peptidoglycan from lipid-linked precursors, were solubilized from the membranes of Staphylococcus aureus and Micrococcus luteus and were partially purified [5].

High impact information on pilT

• The R gene product, a transglycosylase, is released through the pore to the periplasm, resulting in destruction of the peptidoglycan and bursting of the cell [6].
• PBP1C is a close homologue to the bifunctional transpeptidases/transglycosylases PBP1A and PBP1B and likewise shows murein polymerizing activity, which can be blocked by the transglycosylase inhibitor moenomycin [7].
• The transglycosylase activity of the membranes was sensitive to enramycin and vancomycin and was unusual in being stimulated greatly by a high concentration of a chelating agent [8].
• Functional biosynthesis of cell wall peptidoglycan by polymorphic bifunctional polypeptides. Penicillin-binding protein 1Bs of Escherichia coli with activities of transglycosylase and transpeptidase [9].
• The predicted catalytic glutamate residue for transglycosylase activity of bacteriophage T7 gp16 is not essential for phage growth, but is shown to be beneficial during infection of Escherichia coli cells grown to high cell density, conditions in which murein is more highly cross-linked [2].

Chemical compound and disease context of pilT

• In the first step, radiolabeled lipid II, the TG substrate, was made in membranes of the E. coli ponB::Spc(r) strain by incubation with the peptidoglycan sugar precursors [10].
• The amounts of these hypo-modified tRNAs can be determined easily by measuring incorporation of labeled guanine into tRNA with Escherichia coli tRNA--guanine transglycosylase [11].
• Penicillin-binding protein (pbp) 1b, the main DD-transpeptidase/transglycosylase of Escherichia coli, is normally present in the cell in three molecular forms alpha, beta and gamma, differentiated by their mobility in sodium dodecyl sulfate/polyacrylamide gel electrophoresis [12].

Biological context of pilT

• Restoration of the normal phenotypes is also possible by introduction of the pilT gene encoded by the unrelated IncI plasmid R64 [13].
• Penicillin binding protein (PBP) 1b of Escherichia coli has both transglycosylase and transpeptidase activities, which are attractive targets for the discovery of new antibacterial agents [14].
• A simple assay for detection of compounds that bind to the active site in the transglycosylation domain of the essential bifunctional transglycosylase and transpeptidase penicillin-binding proteins (PBPs) is reported [15].
• With similar amino acid sequences and modular designs, M. leprae PBP1 is related to Escherichia coli PBP1a and PBP1b, bienzymatic proteins with transglycosylase and transpeptidase activities [16].
• (X = N-acetylglucosaminyl-1,6-anhydro-N-acetylmuramyl-L-alanyl-D-gamma-glutamyl-meso-diaminopimelic acid; X' = X-D-alanine.) The kinetics of the activity of the membrane-bound enzyme were found to be identical to that of the soluble enzyme, indicating that both molecular species of transglycosylase function as exoenzymes in vitro [17].

Associations of pilT with chemical compounds

• It has no detectable transglycosylase activity with lipid II as substrate [18].
• Surprisingly, tunicamycin and nisin also inhibited the assay, and paper chromatography analysis revealed that both inhibited the transglycosylase [10].
• In eubacteria, the tRNA transglycosylase (Tgt) in specific tRNAs exchanges a guanine in the anticodon for 7-aminomethyl-7-deazaguanine, which is finally converted to queuosine [19].
• Moenomycin, a TG inhibitor, also inhibited TP activity [20].
• To determine whether transglycosylase released muropeptide first from the N-acetylglucosaminyl or the 1,6-anhydromuramyl ends of the glycan chains, the [3H]diaminopimelate-labeled sacculi were further radiolabeled at their N-acetylglucosaminyl ends with [14C]galactose by a galactosyl transferase reaction [17].

Other interactions of pilT

• The pilK, pilR, and pilT products were produced with a C-terminal His tag and then detected by anti-His tag antibody [21].

Analytical, diagnostic and therapeutic context of pilT

• Some aspects of the blue Sepharose affinity chromatography and the possible biological significance of the transglycosylase are discussed [22].
• We improved and simplified the purification procedure for the membrane-derived transglycosylase and characterized the two enzymes in more detail by peptide mapping and by immunological procedures [23].
• A novel assay based on surface plasmon resonance (SPR) has been established that can be used to investigate selective binding of the moenomycin sugar moiety and other transglycosylase inhibitors to this enzyme [24].

References