ABSTRACT
An enzyme which catalyzes the conversion of GlcNAc-PP-undecaprenol into ManNAc(beta 1----4)GlcNAc-PP-undecaprenol, a key lipid intermediate in the de novo synthesis of various teichoic acids, was partially purified from the 20,000 x g supernatant fraction of Bacillus subtilis AHU 1035 cell homogenate. By means of ammonium sulfate precipitation, gel chromatography, and ion-exchange chromatography, the enzyme was purified about 70-fold, giving a preparation virtually free from substances obstructive to measurement of the N-acetylmannosaminyltransferase reaction. The enzyme was shown to be specific to UDP-ManNAc. The Km value for UDP-ManNAc was 4.4 microM, and the optimum pH was 7.3. The enzyme required 10 mM MgCl2, 0.3 M KCl, 25% glycerol, and 0.1% Nonidet P-40 to function at full activity.
Subject(s)
Bacillus subtilis/enzymology , Hexosyltransferases/isolation & purification , Mannosyltransferases/isolation & purification , N-Acetylglucosaminyltransferases , N-Acetylhexosaminyltransferases , Transaminases/isolation & purification , Carbohydrate Conformation , Chromatography , Glucosyltransferases , Glycolipids , Hydrogen-Ion Concentration , Kinetics , Mannosyltransferases/metabolism , Substrate Specificity , Teichoic Acids/biosynthesis , Uridine Diphosphate SugarsABSTRACT
The glucosyltransferase which catalyzes the conversion of GlcNAc-PP-undecaprenol into Glc(beta 1----4)GlcNAc-PP-undecaprenol in the presence of UDP-glucose was solubilized from Bacillus coagulans AHU 1366 membranes by treatment with 0.1% Triton X-100 and partially purified by means of column chromatography on Sephacryl S-300 and DEAE-Sephacel. The final preparation was virtually free from other enzymes involved in the de novo synthesis of teichoic acid. The enzyme had a pH optimum of 6.6-8.0 and a Km value for UDP-glucose of 21 microM. The enzyme required 40 mM MgCl2, 0.6 M KCl, and 0.1% Nonidet P-40 for full activity.
Subject(s)
Bacillus/enzymology , Glucosyltransferases/isolation & purification , Chromatography , Glucosyltransferases/metabolism , Glycolipids , Hydrogen-Ion Concentration , Kinetics , Membranes/enzymology , Solubility , Substrate Specificity , Teichoic Acids/biosynthesis , Uridine Diphosphate Glucose , Uridine Diphosphate SugarsABSTRACT
A novel enzyme which specifically hydrolyzes N-acetylglucosaminyl pyrophosphorylpolyprenol to liberate N-acetylglucosamine was found in membranes of Bacillus polymyxa AHU 1385. The enzyme seems to be inactive toward alpha-N-acetylglucosaminyl phosphorylundecaprenol, beta-N-acetylglucosaminyl phosphorylundecaprenol, N-acetylglucosamine 1-phosphate, N-acetylglucosamine 1-pyrophosphate, or UDP-N-acetylglucosamine. Much lower activities of the same enzyme were also found in membranes of several other strains of Bacilli.
Subject(s)
Acetylglucosamine/metabolism , Bacillus/enzymology , Bacterial Proteins/isolation & purification , Glucosamine/analogs & derivatives , Membrane Proteins/isolation & purification , Phosphoric Diester Hydrolases/isolation & purification , Polyisoprenyl Phosphate Monosaccharides/metabolism , Polyisoprenyl Phosphate Sugars/metabolism , Bacterial Proteins/metabolism , Hydrolysis , Membrane Proteins/metabolism , Phosphoric Diester Hydrolases/metabolism , Species Specificity , Substrate SpecificityABSTRACT
The pathway for the biosynthesis of a cell wall polysaccharide, composed of glucosamine, mannosamine, galactosamine and glucose in a molar ratio of 4:1:1:1, was studied with a membrane system from Bacillus cereus AHU 1356. In this system a glycolipid characterized as GalNAc(alpha 1----4)ManNAc(beta 1----4)GlcNAc-PP-undecaprenol was formed from GlcNAc-PP-undecaprenol by sequential transfer of N-acetylmannosamine and N-acetylgalactosamine residues from UDP-ManNAc and UDP-GalNAc respectively. An additional N-acetylglucosamine residue and a glucose residue were individually transferred from their UDP derivatives to the trisaccharide-linked lipid with the formation of tetrasaccharide-linked lipids, which seem to serve as intermediates in the polysaccharide synthesis. Incubation of membranes with the trisaccharide-linked lipid even in the absence of sugar-linked nucleotides led to the formation of polysaccharide. These results, together with the data on Smith degradation of the synthesized polysaccharide, indicate that the repeating trisaccharide units of the main chain of the polysaccharide arise from the GalNAc-ManNAc-GlcNAc moiety of the glycolipid intermediates and that the sugar residues in the lateral branches of the polymer are at least partly introduced through oligosaccharide-linked lipid intermediates. In addition, the structure of native polysaccharide was re-examined, and the presence of the disaccharide sequence ManNAc(beta 1----4)GlcNAc in the polysaccharide chain was confirmed.
Subject(s)
Bacillus cereus/metabolism , Cell Wall/metabolism , Polysaccharides, Bacterial/biosynthesis , Affinity Labels , Chemical Phenomena , Chemistry , Chromatography, Thin Layer , Glycolipids/isolation & purification , Hydrogen-Ion Concentration , Polymers/analysis , Structure-Activity RelationshipSubject(s)
Bacillus cereus/metabolism , Disaccharides/biosynthesis , Teichoic Acids/biosynthesis , Bacillus cereus/drug effects , Cell Wall/metabolism , Glycolipids/biosynthesis , Nucleoside Diphosphate Sugars/pharmacology , Tunicamycin/pharmacology , Uridine Diphosphate N-Acetylglucosamine/metabolismABSTRACT
The structural difference was studied between two N-acetylglucosaminyl phosphorylundecaprenols formed by incubation of Bacillus cereus membranes with UDP-N-acetylglucosamine. On the treatment with 50% phenol, the major one of these glycolipids (Lipid 1) yielded a saccharide phosphate, while the other (Lipid 2) yielded N-acetylglucosamine along with a saccharide phosphate. The saccharide phosphates from Lipids 1 and 2 were identified as alpha-N-acetylglucosamine 1-phosphate and its beta-anomer, respectively, based on their susceptibility to acid, alpha- and beta-N-acetylglucosaminidases, and UDP-N-acetylglucosamine pyrophosphorylase. Thus, it seems most probable that Lipids 1 and 2 were alpha- and beta-N-acetylglucosaminyl phosphorylundecaprenols, respectively.
Subject(s)
Bacillus cereus/metabolism , Membrane Lipids , Polyisoprenyl Phosphate Monosaccharides , Polyisoprenyl Phosphate Sugars , Cell Membrane/metabolism , Kinetics , Membrane Lipids/biosynthesis , Molecular Conformation , Polyisoprenyl Phosphate Monosaccharides/biosynthesis , Polyisoprenyl Phosphate Sugars/biosynthesis , Uridine Diphosphate N-Acetylglucosamine/metabolismABSTRACT
Membranes from Bacillus cereus AHU 1356 incorporated radioactivity from UDP-N-acetyl[14C]glucosamine into three alkaline-stable and acid-labile lipids which were extracted into chloroform:methanol (2:1) and separated from each other by thin layer chromatography on silica gel plates. The major labeled lipid (Lipid 1) and a minor one (Lipid 2) were identified as N-actetylglucosaminyl phosphorylundecaprenol from several analytical criteria involving mass spectral data and from reversal of their formation by UDP. These two lipids appear to differ in geometry of their polyprenol moieties. The third labeled lipid (Lipid 3) was identified as N-acetylglucosaminyl pyrophosphorylundecaprenol. Antibiotic 24010, a tunicamycin-like antibiotic, at 1 microgram/ml was found to inhibit almost completely the formation of Lipid 3, whereas it inhibited the formation of Lipid 1 much more weakly and rather enhanced the formation of Lipid 2. Radioactivity was also incorporated into a polymer from UDP-GlcNAc and from Lipid 3. UDP-N-acetylmannosamine, UDP-N-acetylgalactosamine, and UDP-glucose supported the incorporation. Antibiotic 24010 strongly inhibited the incorporation of radioactivity from UDP-GlcNAc into polymer, whereas it did not affect the incorporation from Lipid 3. Thus, it is concluded that N-acetylglucosaminyl pyrophosphorylundecaprenol serves as a precursor in the synthesis of a polymer presumed as the cell wall polysaccharide of this bacterial strain.
