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C Wanke

Publications and source records attributed to C Wanke.

28 records · Page 2Linked to original sources
PubMed1994

Detection of the covalent intermediate of UDP-N-acetylglucosamine enolpyruvyl transferase by solution-state and time-resolved solid-state NMR spectroscopy.

Uridine diphosphate-N-acetylglucosamine (UDP-NAG) enolpyruvyl transferase from Enterobacter cloacae catalyzes the transfer of an enolpyruvyl moiety from phosphoenolpyruvate (PEP) to the 3-hydroxyl of UDP-NAG to form enolpyruvyl UDP-NAG and inorganic phosphate. Indirect evidence for the involvement of a covalent intermediate, in which the C-2 of O-phosphothioketal moiety is attached to Cys-115, in the reaction catalyzed by UDP-NAG enolpyruvyl transferase has been reported by Wanke and Amrhein [Wanke, C., & Amrhein, N. (1993) Eur. J. Biochem. 218, 861-870]. In the enzyme from Escherichia coli, a noncovalent tetrahedral intermediate in which the C-2 of PEP is attached to the 3-OH of UDP-NAG via an ether linkage has been isolated by Marquardt et al. [Marquardt, J.L., Brown, E.D., Walsh, C.T., & Anderson, K.S. (1993) J. Am. Chem. Soc. 115, 10398-10399]. In this study, we provide direct evidence for the formation of a covalent O-phosphothioketal enzyme intermediate from UDP-NAG enolpyruvyl transferase of E. cloacae overexpressed in E. coli. The intermediate was obtained by incubation of the enzyme with [2,3-13C2]PEP and UDP-NAG and was characterized by solution-state 1D 13C and 31P NMR, 13C DEPT NMR, and 1H[13C]2D HMQC NMR spectroscopy. The 13C NMR spectra showed two coupled resonances at 29.3 and 88.7 ppm which were assigned to the C-3 and C-2 of the covalent intermediate, and the 13C DEPT confirmed that C-3 was a methyl group and C-2 was quaternary.(ABSTRACT TRUNCATED AT 250 WORDS)

Alkyl and Aryl Transferases↗
PubMed1994

Liver abscesses due to Staphylococcus aureus in a patient with AIDS who underwent small bowel biopsy: case report and review.

A 36-year-old man with overgrowth of Staphylococcus aureus in the small bowel underwent a biopsy of the small bowel and presented 5 weeks later with multiple liver abscesses. To our knowledge, small bowel biopsy has never been associated with liver abscesses. We discuss the literature on liver abscesses in patients with AIDS and the risks of bacteremia following upper endoscopy and small bowel biopsy and propose that the etiology of the liver abscesses in our patient was seeding of the portal vein following biopsy of a small bowel that had significant bacterial overgrowth.

AIDS-Related Opportunistic Infections↗
PubMed1993

Evidence that the reaction of the UDP-N-acetylglucosamine 1-carboxyvinyltransferase proceeds through the O-phosphothioketal of pyruvic acid bound to Cys115 of the enzyme.

The enzyme UDP-N-acetylglucosamine 1-carboxyvinyltransferase (enolpyruvyltransferase, EC 2.5.1.7) catalyses the transfer of the intact 1-carboxyvinyl moiety of phosphoenolpyruvate to the 3'-hydroxyl group of the glucosamine moiety of UDP-(2')-N-acetylglucosamine with the concomitant release of inorganic phosphate, the first committed step in the biosynthesis of the bacterial cell wall peptidoglycan. Overexpression of the enzyme from Enterobacter cloacae in Escherichia coli allowed the isolation of large amounts of purified enzyme (approx. 900 mg/20 g fresh mass bacteria). By incubating the enzyme with 14C-labelled phosphoenolpyruvate, 32P-labelled orthophosphate and unlabelled UDP-(2')-N-acetyl-(3')-1-carboxyvinylglucosamine, we were able to isolate and characterise a reaction intermediate, covalently bound to the protein. It contains stoichiometric quantities of the C3 moiety (0.98 mol/mol) as well as of the phosphate moiety (0.95 mol/mol) of phosphoenolpyruvate relative to protein. The rapid turnover of this protein-bound intermediate in the presence of UDP-(2')-N-acetylglucosamine towards the product UDP-(2')-N-acetyl-(3')-1-carboxyvinylglucosamine suggests that the intermediate is kinetically competent. We also present evidence that the intermediate is bound as the O-phosphothioketal of pyruvic acid to Cys115 of the enzyme. This is the same Cys residue to which phosphomycin, an irreversible inhibitor of the UDP-GlcNAc carboxyvinyltransferase, binds covalently. Exchange of Cys115 for a Ser residue resulted in an inactive enzyme, demonstrating the essential role of Cys115 for the reaction. The only other enzyme known to catalyse the transfer of the intact 1-carboxyvinyl moiety of phosphoenolpyruvate to a substrate is the 3-phosphoshikimate 1-carboxyvinyltransferase (EC 2.5.1.19), the sixth enzyme of the shikimate pathway. The reaction of this synthase is known to proceed through a single, tightly but not covalently bound, tetrahedral intermediate. Even though the two enzymes share similarities in their primary amino acid sequences, their reaction mechanisms appear to be substantially different.

Alkyl and Aryl Transferases↗
PubMed1993

Production of mucinase and neuraminidase and binding of Shigella to intestinal mucin.

Production of mucinase and neuraminidase by Shigella spp. and their ability to bind to mucin was investigated. All four species of Shigella produced these enzymes. Virulent and avirulent pairs of Shigella did not differ in their ability to produce the enzymes after 18 h of growth. However, a significant difference in neuraminidase production was noted in Shigella dysenteriae type 1 and S. boydii (12-15) at 10 h growth. Avirulent strains of S. dysenteriae type 1, S. flexneri 2a, and S. boydii bound significantly more amounts of mucin than their virulent counterparts.

Animals↗
PubMed1992

The UDP-N-acetylglucosamine 1-carboxyvinyl-transferase of Enterobacter cloacae. Molecular cloning, sequencing of the gene and overexpression of the enzyme.

The UDP-N-acetylglucosamine 1-carboxyvinyltransferase (enolpyruvyltransferase, EC 2.5.1.7) which catalyses the first committed step in the biosynthesis of the bacterial cell-wall peptidoglycan was purified to near homogeneity from Enterobacter cloacae and the NH2-terminal amino-acid sequence determined. Using the polymerase chain reaction a 53-bp DNA fragment was synthesized; this fragment encodes the NH2-terminal sequence of the enzyme. A clone was then isolated which contained an open reading frame of 1257 bp coding for a protein of 419 amino acids. This protein was overexpressed 100-fold in transformed Escherichia coli cells and shown to possess the enolpyruvyltransferase activity. The overall amino-acid sequence of the enolpyruvyltransferase is significantly similar to that of the 5-enolpyruvylshikimate 3-phosphate synthase, the only other enzyme known to catalyse the transfer of the enolpyruvate moiety of phosphoenolpyruvate to a substrate.

Alkyl and Aryl Transferases↗
PubMed1988

Epidemiologic and clinical features of invasive amebiasis in Bangladesh: a case-control comparison with other diarrheal diseases and postmortem findings.

To describe the epidemiologic and clinical features associated with invasive amebiasis in Bangladesh, 85 hospitalized diarrheal patients with hematophagous trophozoites of Entamoeba histolytica in their stools were compared to a control group of 84 hospitalized diarrheal patients without amebiasis. Postmortem examinations were carried out in 22 deaths due to amebiasis. For the patients with amebiasis, there was a bimodal age distribution with peaks at 2-3 years and greater than 40 years, whereas the control patients had a unimodal distribution with the peak at 0-1 year. The sex distribution was equal in childhood but young adults were predominantly female and older adults predominantly male. The clinical features significantly associated with amebiasis were prolonged dysentery, prior measles rash, malnutrition, hyponatremia, hypokalemia, and hypoproteinemia (all P less than 0.05). The case fatality rate in amebiasis was 29%, which was significantly higher than 11% for the controls (P less than 0.05). Postmortem findings included extensive colitis with deep ulcers and complications, including colonic perforation in 2 cases, peritonitis in 4 cases, pneumonia in 9 cases, and septicemia in 5 cases. These results indicate that invasive amebiasis in this population differs from other diarrheal diseases, affecting mainly children greater than 2 years and adults and causing severe and fatal illness characterized by extensive colitis with diverse systemic consequences.

Adolescent↗
PubMed1987

Toxoplasma encephalitis in patients with acquired immune deficiency syndrome: diagnosis and response to therapy.

Although Toxoplasma gondii is the most commonly recognized cause of central nervous system mass lesions in patients with acquired immune deficiency syndrome, published investigations have provided little information about criteria for diagnosis of toxoplasmosis or the response to therapy. In this series the method of diagnosis and response to therapy were assessed in 14 patients who had evidence for toxoplasmosis based on routine histopathology, immunoperoxidase staining, or mouse inoculation. These patients presented with clinical and radiologic findings that did not clearly distinguish them from patients with other infectious or neoplastic processes. Excisional biopsies usually showed tachyzoites on routine histology, but needle biopsies were usually negative unless mouse inoculation or immunoperoxidase staining was employed. Response to pyrimethamine and sulfadiazine therapy was often prompt, but therapy had to be continued for long periods of time to maintain a clinical response, and no alternative regimen of one or more drugs appeared to be effective in patients unable to tolerate both pyrimethamine and sulfadiazine.

Acquired Immunodeficiency Syndrome↗
PubMedDate not supplied

Crystallization and preliminary X-ray diffraction analysis of UDP-N-acetylglucosamine enolpyruvyltransferase of Enterobacter cloacae.

Single crystals of UDP-N-acetylglucosamine enolpyruvyltransferase of Enterobacter cloacae have been grown by vapor diffusion using phosphate buffer as the precipitant. The crystals belong to the monoclinic space group C2 with a = 86.9 A, b = 155.9 A, c = 83.8 A, beta = 91.6 degrees. Assuming two monomers per asymmetric unit, the solvent content of these crystals is 63%. Flash-frozen crystals diffract to beyond 2 A resolution.

Alkyl and Aryl Transferases↗