Characterization of a polyisoprenoid compound functional in O-antigen biosynthesis

Isolation of polyisoprenyl alcohols from Streptococcus faecalis

C(55)-isoprenyl alcohol and its derivatives have been isolated from Streptococcus faecalis and characterized. The relative amounts present as free alcohol, neutral lipid esters, and phosphate ester derivatives were determined. The chain lengths, mass spectra, and cis to trans ratio of double bonds are reported.

Isolation of the lipid intermediate in peptidoglycan biosynthesis from Escherichia coli

The lipid intermediate in peptidoglycan biosynthesis was isolated from Escherichia coli strain W and characterized as C(55)-isoprenyl-pyrophosphoryl N-acetylmuramyl(-pentapeptide)-N-acetyl-glucosamine.

Formation of polyisoprenol phosphate glucose in Shigella flexneri

Lipid-linked glucose is formed from uridine diphosphate-glucose and ficaprenol phosphate only in strains of Shigella flexneri with glucosylated O antigen.

The biosynthesis of C 55 polyprenols by a cell-free preparation of Lactobacillus plantarum

A cell-free supernatant of lysates of Lactobacillus plantarum catalyses the synthesis of lipids from [2-(14)C]mevalonate. Of the added mevalonate, 7.5% is incorporated into lipids, which were fractionated into five components. About 4% of the radioactivity in these lipids co-chromatographs with compounds shown by mass spectrometry, n.m.r. and i.r. spectroscopy to be C(55) polyprenols, and about 2% co-chromatographs with a hexamer. The rest of the radioactivity is in more complex fractions. Analysis by mass spectrometry, n.m.r. and i.r. spectroscopy shows that the major C(55) polyprenol is undecaprenol, accompanied by an isomer containing one reduced isoprene unit. A Kuhn-Roth degradation of [(14)C]polyprenols indicates that the supernatant catalyses synthesis of these compounds de novo.

Biosynthesis of the wall teichoic acid in Bacillus licheniformis

1. The biosynthesis of the wall teichoic acid, poly(glycerol phosphate glucose), has been studied with a particulate membrane preparation from Bacillus licheniformis A.T.C.C. 9945. The precursor CDP-glycerol supplies glycerol phosphate residues, whereas UDP-glucose supplies only glucose to the repeating structure of the polymer. 2. Synthesis proceeds through polyprenol phosphate derivatives, and chemical studies and pulse-labelling techniques show that the first intermediate is the phosphodiester, glucose polyprenol monophosphate. CDP-glycerol donates a glycerol phosphate residue to this to give a second intermediate, (glycerol phosphate glucose phosphate) polyprenol. 3. The glucose residue in the lipid intermediates has the beta configuration, and chain extension in the synthesis of polymer occurs by transglycosylation with inversion of anomeric configuration at two stages.

Lipid intermediates in the biosynthesis of the wall teichoic acid in Staphylococcus lactis 13

1. Particulate enzyme systems have been prepared from Staphylococcus lactis I3 which effect the synthesis of wall teichoic acid (a polymer containing a repeating unit in which d-glycerol 1-phosphate is attached to the 4-position on N-acetylglucosamine 1-phosphate) from the nucleotide precursors CDP-glycerol and UDP-N-acetylglucosamine. By using nucleotides labelled with (32)P and (14)C it has been shown that the synthesis proceeds via lipid intermediates. 2. Two intermediates have been found. In one of these N-acetylglucosamine 1-phosphate is present, whereas in the other the repeating unit of the teichoic acid occurs. 3. The simultaneous formation of the teichoic acid, a poly-(N-acetylglucosamine 1-phosphate) and an unidentified lipid, together with the poor ability of most particulate systems to synthesize polymer and the instability of the lipid intermediates themselves, have interfered with pulse-labelling experiments. Nevertheless, the biosynthetic sequence has been elucidated. It is concluded that the intermediates are derivatives of undecaprenol phosphate.

Protein-polysaccharide biosynthesis. Membrane-bound saccharides

Membrane-bound saccharides obtained from ear cartilage from rabbits recovering from papain injection were examined for glycosyl acceptor properties, alkali lability, molecular size and degree of sulphation. Although considerable glucuronosyl transfer from UDP-glucuronic acid could be demonstrated, less than one-third could be identified as representing chondroitin linkage formation; there was little or no effect of molecular size on acceptor properties. Approximately one-half of the membrane-associated chondroitin-like saccharide chains are solubilized by alkali, whereas one-half require proteolysis for solubilization. These fractions are analytically indistinguishable and both contain xylose and galactose as well as uronic acid and sulphated N-acetyl-galactosamine. All fragments that were examined contained stoicheiometric amounts of axial sulphate ester, strongly suggesting a close relationship between chain extension and sulphation.

Glucose transfer from dolichol monophosphate glucose: the product formed with endogenous microsomal acceptor

The product formed by incubation of dolichol monophosphate glucose with liver microsomes was studied. It is insoluble in most solvents, but is soluble in a chloroform-methanol mixture with a high content of water. Treatment with ammonia gave rise to the formation of a water soluble, negatively charged compound of molecular weight 3550. The negative charge could be removed by treatment with phosphatase. Acid hydrolysis of the original compound led to the liberation of an uncharged, water-soluble compound (molecular weight 3550). Acetolysis of the latter gave rise to the formation of a series of products, which appeared to be oligosaccharides when chromatographed on paper or silica plates. The original substance behaved like a polyprenol pyrophosphate when chromatographed on DEAE-cellulose. Molecular weight measurements of the deoxycholate inclusion compound gave a value of 14,300, while dolichol monophosphate glucose under the same conditions gave 11,300. It is tentatively suggested that the compound is dolichol joined through a phosphate or pyrophosphate bridge to an oligosaccharide containing about 20 monosaccharide residues.

Ubiquinone biosynthesis in Escherichia coli K-12. Accumulation of an octaprenol, farnesylfarnesylgeraniol, by a multiple aromatic auxotroph

Cell extracts of a multiple aromatic auxotroph of Escherichia coli K-12, strain AB2830, grown in the absence of precursors of the quinone rings of the ubiquinone and menaquinone molecules, converted 4-hydroxy[U-(14)C]benzoate into a mixture of 3-octaprenyl-4-hydroxybenzoate and 2-octaprenylphenol. An octaprenol, farnesylfarnesylgeraniol, was isolated from such cell extracts and characterized by n.m.r. and mass spectroscopy. Neither the octaprenol, nor polyprenylation of 4-hydroxy[U-(14)C]benzoate, could be detected in cell extracts of strain AB2830 grown in the presence of 0.1mm-4-hydroxybenzoate. It was concluded that, in the biosynthesis of ubiquinone, the polyprenyl side chain is added to 4-hydroxybenzoate as a C(40) unit, the active form of which is converted by cell extracts into farnesylfarnesylgeraniol. The multiple aromatic auxotroph, when grown in the absence of 4-hydroxybenzoate but in the presence of 4-aminobenzoate, converted the latter compound into 3-octaprenyl-4-aminobenzoate. This compound was isolated from whole cells and characterized by n.m.r. and mass spectroscopy.

Glucosylation of teichoic acid: solubilization and partial characterization of the uridine diphosphoglucose: polyglycerolteichoic acid glucosyl transferase from membranes of Bacillus subtilis

Polyglycerolteichoic acid:glucosyl transferase (TAG transferase), one of the three enzymes involved in the pathway leading to the glucosylation of teichoic acid in Bacillus subtilis 168, was investigated. During the early stages of the growth of B. subtilis, TAG transferase is predominantly a soluble enzyme found in the cytoplasm. As growth proceeds, the amount of soluble enzyme decreases and the proportion of insoluble, membrane-bound TAG transferase increases, reaching a maximal value at the close of the logarithmic phase. Data are presented which suggest that these are two forms of the same enzyme, or have some common component. The effects of chaotropic agents, such as sodium trichloroacetate and sodium perchlorate, on the cytoplasmic membrane were also studied. These data show that such compounds can effectively remove the TAG transferase from the membrane in a water-soluble form. A study of some of the physical properties of this solubilized enzyme suggests that there is little difference between the two forms of the enzyme. Experiments are described which indicate that the glucosyl transfer by both the membrane-bound and soluble enzymes is not mediated by lipids.

Role of lipids in the biosynthesis of the bacterial cell envelope

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Biosynthesis of T1 antigen in Salmonella: biosynthesis in a cell-free system

A particulate fraction from a T1 form of Salmonella typhimurium incorporated radioactivity from uridine diphosphate (UDP)-(14)C-glucose into products associated with the particulate enzyme. A major fraction of the incorporated radioactivity was found in the cell wall lipopolysaccharide fraction. Acid hydrolysis of incorporation products produced labeled galactose, ribose, and also glucose. The incorporation of glucose could be dissociated from the incorporation of galactose and ribose under certain conditions, and was assumed to represent incorporation into a polymer not related to T1 antigen. The incorporation of galactose and ribose probably represented the synthesis of T1 side chains of lipopolysaccharide, because (i) particulate fractions from non-T1 strains incorporated much less of these sugars and (ii) periodate oxidation and borohydride reduction converted a large portion of incorporated galactose residues into arabinose. The latter finding indicates that the galactose residues are galactofuranosides substituted either at C2 or C3; about 70% of the galactose residues in T1 side chains are known to be galactofuranosides substituted at C3. UDP-(14)C-galactose preparation used was not contaminated by UDP-(14)C-galactofuranose; therefore pyranose-to-furanose conversion must have taken place at some step during the reactions described above. The mechanism of conversion of galactose to ribose is not clear, but it was not found to involve a selective elimination of C1 or C6 of galactose or glucose.

Mechanism of conversion of the salmonella O antigen by bacteriophageepsilon 34

The structural determinants for antigen 34 in the E group salmonella are glucosyl substituents on the galactosyl units of the O antigen which has a mannosylrhamnosylgalactose repeating sequence. The temperate bacteriophage epsilon(34) brings about the production of antigen 34. It has been shown here that glucose is transferred from uridine diphosphate glucose to the O antigen via a glucosyl-lipid intermediate in a two-step reaction. Glucose is linked through carbon 1 to the lipid by a phosphodiester bridge, the glucosyl bond having the beta-anomeric configuration. The lipid is a C(55)-polyisoprenoid alcohol, each isoprene unit having one double bond. It is the same lipid which is involved in the synthesis of the O antigen repeating sequence.

Bacterial glycolipids

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The synthesis of exopolysaccharide by Klebsiella aerogenes membrane preparations and the involvement of lipid intermediates

1. Membrane preparations from Klebsiella aerogenes type 8 were shown to transfer glucose and galactose from their uridine diphosphate derivatives to a lipid and to polymer. The ratio of glucose to galactose transfer in both cases was 1:2. This is the same ratio in which these sugars occur in native polysaccharide. Galactose transfer was dependent on prior glucosylation of the lipid. Mutants were obtained lacking (a) glucosyltransferase and (b) galactosyltransferase. The transferase activities in a number of non-mucoid mutants was examined. 2. Glucose transfer was partially inhibited by uridine monophosphate, and incorporation of either glucose or galactose into lipid was decreased in the presence of uridine diphosphate. The sugars are thought to be linked to a lipid through a pyrophosphate bond, and treatment of the lipid intermediates with phenol yielded water-soluble compounds. These could be dephosphorylated with alkaline phosphatase. Transfer of glucuronic acid to lipid or polymer from uridine diphosphate glucuronic acid was much lower than that of the other two sugars. 3. The fate of sugars incorporated into polymer was also followed. Some conversion of glucose into galactose and glucuronic acid occurred. Mutants unable to transfer glucose or galactose to lipid were unable to form polymer. Other mutants capable of lipid glycosylation were in some cases unable to form polymer. A model for capsular polysaccharide synthesis is proposed and its similarity to the formation of other polymers outside the cell membrane is discussed.

Mechanism of polymerization of the Salmonella O-antigen: utilization of lipid-linked intermediates

Cell envelope fractions from Salmonella can utilize exogenous lipid-linked intermediates for the synthesis of polymeric O-antigen. We describe a method for preparing aqueous suspensions of lipid intermediates and show that freezing and thawing of cell envelope-lipid intermediate mixtures is required for efficient synthesis. The lipid intermediates move freely in the hydrophobic environment of the membrane.

The characterization of undecaprenol of Lactobacillus plantarum

Evidence for the presence of undecaprenol in the unsaponifiable lipid of Lactobacillus plantarum (N.C.I.B. 6376) is presented. Characterization of the compound was based mainly on mass, i.r. and n.m.r. spectrometry. The prenol was isolated at a concentration of 40mug/g wet wt. of bacteria and contained over 90% (1.0-5.4% of the dose) of the (14)C present in the unsaponifiable lipid after incubation of the bacteria with [2-(14)C]mevalonate. N.m.r. spectrometry indicated the presence of two internal trans-, one alpha-cis- and seven internal cis-isoprene residues per molecule. The (3)H/(14)C ratios of the prenol after incubation of the bacteria with [2-(14)C,(4R)-4-(3)H(1)]- and [2-(14)C,(4S)-4-(3)H(1)]-mevalonate were in agreement with this stereochemistry. There was no evidence of saturated isoprene residues in the molecule. The undecaprenol appeared to be accompanied by much smaller quantities of decaprenol and nonaprenol.

Dolichol monophosphate glucose: an intermediate in glucose transfer in liver

The microsomal fraction of liver has been found to catalyze glucose transfer from UDPG to a lipid acceptor which appears to be identical to the compound obtained by chemical phosphorylation of dolichol. The substance formed (dolichol monophosphate glucose) is acid labile and yields 1,6-anhydroglucosan by alkaline treatment. It can be used as substrate by the enzyme system yielding a glucoprotein which is subsequently hydrolyzed to glucose.

A lipid intermediate in the synthesis of a poly-(N-acetylglucosamine 1-phosphate) from the wall of Staphylococcus lactis N.C.T.C. 2102

1. The enzymic synthesis of the wall polymer poly-(N-acetylglucosamine 1-phosphate) in Staphylococcus lactis N.C.T.C. 2102 was studied by using UDP-[acetyl-(14)C]N-acetylglucosamine and the corresponding nucleotide containing (32)P. 2. Labelled material was extracted from the particulate enzyme preparation with butan-1-ol. Pulse-labelling experiments indicated that this material contained an intermediate in the biosynthesis. 3. The lipid intermediate was partially purified, and chemical and enzymic degradation showed that it was composed of N-acetylglucosamine 1-pyrophosphate in labile ester linkage to an organic-soluble alcohol, possibly a polyisoprenoid alcohol. The methanolysis of sugar 1-pyrophosphate derivatives, including nucleoside diphosphate sugars, is discussed in relation to degradation products obtained from the lipid. 4. The lipids from the particulate enzyme preparation probably contained another compound in which N-acetylglucosamine 1-phosphate is attached to an organic-soluble alcohol; this may participate in the biosynthesis of another polysaccharide. 5. The function of the lipid intermediate in polymer biosynthesis is discussed.

Biosynthesis of cell wall lipopolysaccharide in mutants of Salmonella. V. A mutant of Salmonella typhimurium defective in the synthesis of cytidine diphosphoabequose

A mutant of Salmonella typhimurium LT2 was found to be unable to convert cytidine diphospho-4-keto-6-deoxy-d-glucose into cytidine diphosphoabequose. The mutation maps in the rfb gene cluster, which is known to be involved in the biosynthesis of the peripheral, "O side-chain" portion of cell wall lipopolysaccharide. In spite of the fact that, in the O side chains, abequose is not a part of the main chain but occurs as short branches, the mutant appears to be unable to polymerize oligosaccharide "repeat units" into long O side chains. The following evidence indicates that this failure is the result of the absence of cytidine diphosphoabequose rather than that of a superimposed second mutation in other genes of the rfb cluster. (i) The mutant does not behave like a multisite mutant in genetic crosses, and it gives rise, at a high frequency, to "revertants" where the ability to synthesize cytidine diphosphoabequose and the ability to synthesize normal lipopolysaccharide with O side chains are both restored. (ii) The mutant strain has normal levels of activity of all of the other enzymes known to be involved in O side-chain synthesis, except that the levels of several enzymes were lowered by about 30% owing to the polarity effect of the mutation. That the lowering of these enzymes is not responsible for the failure of the mutant to synthesize O side chains is clear from the fact that there were revertants which had regained some ability to synthesize abequose but still had lowered levels of these other enzymes, and that this type of revertant produced lipopolysaccharide with considerable amounts of O side chains.

The mechanism of biosynthesis and direction of chain extension of a poly-(N-acetylglucosamine 1-phosphate) from the walls of Staphylococcus lactis N.C.T.C. 2102

1. The synthesis of a polymer of N-acetylglucosamine 1-phosphate, occurring in the walls of Staphylococcus lactis N.C.T.C. 2102, was examined by using cell-free enzyme preparations. The enzyme system was particulate, and probably represents fragmented cytoplasmic membrane. 2. Uridine diphosphate N-acetylglucosamine was the only substrate required for polymer synthesis and labelled substrate was used to show that N-acetylglucosamine 1-phosphate is transferred as an intact unit from substrate to polymer. 3. The properties of the enzyme system were studied. A high concentration of Mg(2+) or Mn(2+) was required for optimum activity, and the pH optimum was about 8.5. 4. End-group analysis during synthesis in vitro showed that newly formed chains contain up to about 15 repeating units. Pulse-labelling indicated that chain extension occurs by transfer from the nucleotide to the ;sugar-end' of the chain, i.e. to the end that is not attached to peptidoglycan in the wall.