Controlled acid hydrolysis of an O-antigen fragment yields univalent heptasaccharide haptens containing one 3,6-dideoxyhexose epitope.
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Antibodies↗
Biomedical subjects
E Altman
Publications and source records attributed to E Altman.
Structural studies of the O-antigenic polysaccharide of Fusobacterium necrophorum.
The O-specific polysaccharide component of the lipopolysaccharide produced by Fusobacterium necrophorum is of the teichoic acid type, with repeating units connected by phosphoric diester linkages. Dephosphorylation of the polysaccharide by treatment with aqueous hydrogen fluoride yielded a carbohydrate composed of a trisaccharide linked to an acidic component. This product, and the polysaccharide, were investigated by chemical methods and 1H-, 13C-, 31P- and 15N-NMR spectroscopy and the former also by fast-atom-bombardment mass spectrometry. It is proposed that the polysaccharide is composed of repeating units having the following structure, in which Fuc represents fucose (6-deoxy-galactose), Am represents an acetamidino group and Sug 2,4-diamino-2,4,6-trideoxy-D-glucose ('bacillosamine') acetylated at the 2-position and acylated with a (S)-3-hydroxybutanoic acid at the 4-position. The acid was identified as a 2-amino-2-deoxy-2-C-methyl-pentonic acid (2-amino-2-methyl-3,4,5-trihydroxypentanoic acid). The configuration of this acid remains to be determined. [formula: see text]
Abscess↗
Accumulation of secretory protein precursors in Escherichia coli induces the heat shock response.
The accumulation of secretory protein precursors, caused either by mutations in secB or secA or by the overproduction of export-defective proteins, results in a two- to fivefold increase in the synthesis of heat shock proteins. In such strains, sigma 32, the alternative sigma factor responsible for transcription of the heat shock genes, is stabilized. The resultant increase in the level of sigma 32 leads to increased transcription of heat shock genes and increased synthesis of heat shock proteins. We have also found that although a secB null mutant does not grow on rich medium at a temperature range of 30 to 42 degrees C, it does grow at 44 degrees C. In addition, we found that a secB null mutant exhibits greater thermotolerance than the wild-type parental strain. Elevated levels of heat shock proteins, as well as some other non-heat shock proteins, may account for the partial heat resistance of a SecB-lacking strain.
Bacterial Proteins↗
Structure of the glycan chain from the surface layer glycoprotein of Clostridium thermohydrosulfuricum L77-66.
The thermophilic eubacterium Clostridium thermohydrosulfuricum L77-66 is covered by a crystalline surface layer composed of identical glycoprotein subunits which are arranged in a hexagonal lattice with centre-to-centre spacings of approx. 14.3 nm. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis of cell wall preparations showed the presence of several broadened, carbohydrate-containing bands in a molecular mass range of 90 to 200 kDa. A total carbohydrate content of approx. 14% was determined in the purified surface layer glycoprotein. Chemical deglycosylation of this material by trifluoromethanesulfonic acid resulted in the disappearance of the complex banding pattern. Only a single band with a molecular mass of 82 kDa remained visible upon Coomassie staining. After proteolytic digestion of the surface layer glycoprotein a single glycopeptide fraction with an apparent molecular mass of approx. 25 kDa was obtained by gel filtration. Composition analysis, methylation, periodate oxidation and a combination of homonuclear and 1H-detected heteronuclear shift-correlated nuclear magnetic resonance experiments established the following structure for the glycan chain of the surface layer glycoprotein.
Bacterial Outer Membrane Proteins↗
Structure of the capsular polysaccharide of Actinobacillus pleuropneumoniae serotype 5b.
The capsular polysaccharide of Actinobacillus pleuropneumoniae serotype 5b (strain L20) was found to be a high molecular mass polymer composed of 2-acetamido-2-deoxy-D-glucose, D-glucose, and 3-deoxy-D-manno-octulosonic acid (KDO). Methylation analysis, partial hydrolysis and a combination of homonuclear and 1H-detected heteronuclear shift-correlated nuclear magnetic resonance experiments showed the polysaccharide to be a branched polymer of a trisaccharide repeating unit, having the structure: [formula; see text]
Actinobacillus pleuropneumoniae↗
DnaK and DnaJ heat shock proteins participate in protein export in Escherichia coli.
In Escherichia coli secreted proteins must be maintained in an export-competent state before translocation across the cytoplasmic membrane. This function is carried out by a group of proteins called chaperones. SecB is the major chaperone that interacts with precursor proteins before their secretion. We report results indicating that the DnaK and DnaJ heat shock proteins are also involved in the export of several proteins, most likely by acting as their chaperones. Translocation of alkaline phosphatase, a SecB-independent protein, was inhibited in dnaK- and dnaJ- mutant strains, suggesting that export of this protein probably involves DnaK and DnaJ. In addition, DnaK and DnaJ play a critical role in strains lacking SecB. They are required both for viability and for the residual processing of the SecB-dependent proteins LamB and maltose-binding protein (MBP) seen in secB null strains. Furthermore, overproduction of DnaK and DnaJ permits strains lacking SecB to grow in rich medium and accelerates the processing of LamB and MBP. These results suggest that under conditions where SecB becomes limiting, DnaK and DnaJ probably substitute for SecB and facilitate protein export. This provides the cell with a mechanism to overcome a temporary imbalance in the secretion process caused by an abrupt expansion in the pool of precursor proteins.
Alkaline Phosphatase↗
Sensitive titration microcalorimetric study of the binding of Salmonella O-antigenic oligosaccharides by a monoclonal antibody.
The binding of several oligosaccharide haptens by a monoclonal antibody, Se155-4, specific for Salmonella serogroup B O-antigen was studied by titration microcalorimetry. In the software developed by Wiseman et al. [Wiseman, T., Williston, S. & Brandts, J.F. (1989) Anal. Biochem. 17, 131-137] the number of binding sites/macromolecule is one of the optional regression parameters in the non-linear least-squares analysis of the calorimetric data. Instead, an approach was adopted in which the concentration of binding sites was treated as a regression parameter, obviating the requirement for precise values of antibody absorption coefficients and minimizing effects due to partially inactive antibody preparations. Furthermore, performing the least-squares analysis in two steps, first using a differential heat mode and then an integral heat mode, was shown to yield the most accurate results. The technique gave accurate results using not more than 1-2 mumol ligand and less than 7 mg antibody. Haptens 2-5 were oligomers of the O-antigenic repeating unit varying in chain length by 2-5 repeating units and a trisaccharide glycoside 1, which filled the binding site. The latter hapten exhibited a favourable entropy contribution to binding (delta Go = -31 kJ.mol-1; delta Ho = -21 kJ.mol-1 and -T delta So -10 kJ.mol-1), while all four oligomers 2-5 showed a constant binding energy delta Go = -33 kJ.mol-1, composed of increasingly stronger enthalpy forces compensated by an increasingly unfavourable entropy contribution. These observations are compared with results from enzyme immunoassays and a high-resolution crystal structure for the dodecasaccharide 3 bound to the Fab derived from Se155-4.
Antibodies, Monoclonal↗
Heat-shock proteins can substitute for SecB function during protein export in Escherichia coli.
In this study we have shown that (i) induction of the heat-shock response can substitute for SecB function in Escherichia coli, (ii) SecB itself is not a heat-shock protein and (iii) a basal level of heat-shock proteins is required for cells to grow in the absence of a functional SecB protein. Overproduction of DnaK, or GroEL/ES, which were candidates for the heat-shock proteins that could substitute for SecB function, did not rescue the export defect caused when SecB was limiting or absent. In an attempt to identify the heat-shock protein(s) which could substitute for SecB function, unlinked suppressors of secB were isolated and characterized. Interestingly, most of the suppressors mapped to the rpoH locus. Since rpoH encodes sigma 32, the heat-shock transcription factor, it is likely that these suppressors affect the synthesis levels of heat-shock proteins that can substitute for SecB function. The remaining suppressors did not map to any known heat-shock or export genes. Collectively, our data suggest that these suppressors may represent unidentified heat-shock proteins or export factors that act in a manner similar to SecB in facilitating the export process in E. coli.
Bacterial Proteins↗
Structure of the glycan chain from the surface layer glycoprotein of Bacillus alvei CCM 2051.
The cell surface of the mesophilic eubacterium Bacillus alvei CCM 2051 is covered by an oblique arranged surface layer glycoprotein. The subunits revealed by sodium dodecyl sulfate - polyacrylamide gel electrophoresis were distinct bands of molecular masses 140,000, 128,000, and 127,000. Proteolytic degradation of the purified S-layer glycoprotein yielded a single glycopeptide fraction with an apparent molecular mass of ca. 25,000. Methylation analysis in conjunction with two-dimensional nuclear magnetic resonance experiments at 500 MHz established the branched trisaccharide (formula; see text) as the repeating unit for this glycan chain.
Bacillus↗
Effects of unilateral-nondominant vs. bilateral ECT on memory and depression: a preliminary report.
Reported are preliminary results from a randomized, double-blind study comparing the differential effects of unilateral-nondominant (UND) and bilateral (BL) electroconvulsive therapy (ECT) on memory function and clinical efficacy. The study included the serial administration (before, shortly after, and 6 months following a course of ECT) of behavioral ratings and memory tests for dominant and nondominant, anterograde and retrograde memory functions. Thus far, clinical improvement shortly after a course of ECT and 6 months later was significant for the entire sample and did not differ between the UND and BL groups. Most memory ratings worsened significantly after ECT, but returned to baseline levels 6 months later. Surprisingly, the scores generally did not differ between the UND and BL groups at any time point. Clinical implications for choice of administration are discussed.
Aged↗
Psychiatric rating scales in diagnostic assessment and clinical treatment.
This chapter provides a summary and review of the current and most frequently used clinical rating scales, and discusses their specific use and application in the treatment setting. The review includes some comparison of the essential benefits of each instrument and their potential usefulness in dealing with special populations.
Anxiety Disorders↗
Characterization of a region in mature LamB protein that interacts with a component of the export machinery of Escherichia coli.
It has been shown that the synthesis of an export-defective protein can interfere with the normal export process in Escherichia coli by limiting the availability of SecB protein, a component of the export apparatus (Collier, D.N., Bankaitis, V.A., Weiss, J.B., and Bassford, P.J. (1988) Cell 53, 273-283). Consistent with this observation, we find that the interference elicited by an export-defective LamB protein is a titratable response resulting from the limitation of a single ligand. We have mapped the interfering region in LamB to between amino acids 320 and 380 of the mature protein. Expression of this sequence in the form of a LacZ-LamB-LacZ fusion protein elicits the export interference phenotype. Deletion of the sequence from an export-defective LamB protein eliminates the ability of this protein to interfere with the export of other secreted proteins. Together, these findings show that this sequence is both necessary and sufficient to cause export interference. Surprisingly, deletion of this sequence from an otherwise wild-type LamB protein does not cause the mutant LamB product to exhibit any obvious export defect. Based on our results, we propose that SecB interacts with both amino acids 320-380 of mature LamB and the LamB signal sequence during initiation of the export process.
ATP-Binding Cassette Transporters↗
The presence of both the signal sequence and a region of mature LamB protein is required for the interaction of LamB with the export factor SecB.
In the accompanying paper (Altman, E., Bankaitis, V.A., and Emr, S.D. (1990) J. Biol. Chem. 265, 18148-18153) a putative SecB binding site was identified in the mature LamB protein. The export of wild-type LamB was unperturbed when this region was removed, however, suggesting the presence of a second site of interaction between SecB and LamB. In this paper we show that the interference caused by export-defective LamB proteins is influenced by the amount of signal sequence that is present. If a large portion of the signal sequence is deleted then the interference levels are significantly reduced. This result suggests that a region of the signal sequence contributes to the interaction of SecB with the LamB protein. Using anti-SecB affinity chromatography, we demonstrated directly that the association of SecB protein with precursor LamB is dependent on the presence of both the LamB signal sequence and the interfering region which maps to amino acids 320-380 of mature LamB. Although the interfering region is not necessary for the export of wild-type LamB under normal conditions, when the signal sequence is mutationally altered the interfering region is required to promote the efficient export of LamB protein. Also, deletion of the interfering region eliminates the ability of wild-type LamB precursor to be maintained in an export competent conformation in vivo. Collectively, our results indicate that efficient export of the LamB protein is achieved by an interaction with SecB that involves both the LamB signal sequence and the interfering region in mature LamB.
ATP-Binding Cassette Transporters↗
Chemical characterization of the regularly arranged surface layer glycoprotein of Clostridium thermosaccharolyticum D120-70.
Clostridium thermosaccharolyticum D120-70 possesses as its outermost cell envelope layer a square-arranged array of glycoprotein molecules. SDS/polyacrylamide gel electrophoresis of the purified surface layer showed a broadened band in the molecular mass range of about 115 kDa which, upon periodic acid/Schiff staining, gave a positive reaction. After proteolytic degradation of this material, two glycopeptide fractions were obtained. One- and two-dimensional nuclear magnetic resonance studies, together with methylation analysis and periodate oxidation, were used to determine the structures of the polysaccharide portions of these glycopeptides. The combined chemical and spectroscopic evidence suggests the following structures: (formula; see text).
Bacterial Proteins↗
Structural studies of the O-chains of the lipopolysaccharides produced by strains of Actinobacillus (Haemophilus) pleuropneumoniae serotype 5.
The water-phase lipopolysaccharides isolated by phenol-water extraction from the cells of four strains of Actinobacillus pleuropneumoniae serotype 5 (K17, L20, B78-3760, and 81-750) were shown on structural analysis to have O-chain components with the same basic polysaccharide structure of a linear unbranched homopolymer of 1,6-linked beta-D-galactopyranosyl residues, although the linear length of the O-chain varied among different strains. While those of strains B78-3760 and 81-750 were partially O-acetylated, the O-chains of strains K17 and L20 were unsubstituted.
Actinobacillus↗
An approach to assessing and facilitating causal language in adults with learning disabilities based on Piagetian theory.
Salient characteristics associated with Piagetian cognitive stages served as the basis for developing a linguistic taxonomy of causal semantic relations. Causal statements from adults with learning disabilities and normally achieving adults were analyzed and organized within this taxonomy. A relationship between Piagetian cognitive stages and verbal expressions of causality was identified. Based on this relationship, principles of Piagetian cognitive theory were used to design assessment and intervention plans for adults with learning disabilities.
Adolescent↗
Associated diagnoses (comorbidity) in patients with borderline personality disorder.
The authors administered the Diagnostic Interview Schedule to 21 patients with borderline personality disorder. The patients met criteria for various other DSM-III diagnoses, meeting exclusion criteria in some cases, and not in other cases. Frequency distribution of each diagnosis and the diagnoses of each individual patient, are presented. Affective disorder was the most common diagnosis (85%). Of these, 62% had primary major depression, and 23% had secondary depression. Other diagnoses include bipolar disorder, dysthymia, panic, agoraphobia, alcohol and Drug abuse, somatization disorder, and many others. The authors conclude that while borderline disorder may be a sub-affective disorder, a specific diagnostic profile for this disorder that accounts for the presence of other Axis I and Axis II syndromes has yet to be delineated.
Adult↗
Structure of the lipopolysaccharide antigenic O-chain produced by Actinobacillus pleuropneumoniae serotype 4 (ATCC 33 378).
The structure of the antigenic O-polysaccharide part of the S-type lipopolysaccharide produced by Actinobacillus pleuropneumoniae serotype 4 has been determined by periodate oxidation, methylation, partial hydrolysis, and 1H- and 13C-n.m.r. spectroscopy. The O-polysaccharide structure has a branched-tetrasaccharide repeating unit, (----3)-beta-D-Galp-(1----4)-[beta-D-Glcp-(1----3)]-beta-D-GalpNAc- (1----4)-alpha-L-Rhap-(1-)n. The structure resembles that of the lipopolysaccharide O-chain of A. pleuropneumoniae serotype 7, and their common epitopes may account for the apparent serological cross-reactivity observed between the two serotypes when incompletely adsorbed, anticapsular-typing sera are used.
Actinobacillus↗