Structural study on a phosphorylated mannotetraose obtained from the phosphomannan of Candida albicans NIH B-792 strain by acetolysis.
TL;DR: Findings indicate that the size of the major phosphorylated branch of this phosphomannan is the same as that of Saccharomyces cerevisiae.
Abstract: A mixture of phosphorylated manno-oligosaccharides was isolated from the acid-stable domain of phosphomannan of Candida albicans NIH B-792 strain (serotype B) by acetolysis and was fractionated on a column of Bio-Gel P-2 equilibrated with 50 m m pyridine-CH 3 COOH buffer, pH 5.0. A monophosphorylated mannotetraose was isolated as the major constituent. Structural analyses of this phosphate-containing tetraose and its reduction product with NaBH 4 by 1 H, 13 C, and two-dimensional homonuclear Hartmann-Hahn NMR spectroscopies, subsequently, gave results consistent with the structure described below (where Man p represents the mannopyranose unit): It was unexpected that the major phosphorylated branch in the acid-stable domain of the parent phosphomannan of this C. albicans strain is a relatively short mannotetraosyl residue containing solely α-1,2-linked mannopyranose units, and a phosphate group as a 6- O -ester on the intermediary unit adjacent to the nonreducing terminal group. These findings indicate that the size of the major phosphorylated branch of this phosphomannan is the same as that of Saccharomyces cerevisiae .
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TL;DR: Surface mannoproteins are strong immunogens that trigger and modulate the host immune response during candidiasis and may play a role in morphogenesis.
Abstract: The cell wall is essential to nearly every aspect of the biology and pathogenicity of Candida albicans. Although it was intially considered an almost inert cellular structure that protected the protoplast against osmotic offense, more recent studies have demonstrated that it is a dynamic organelle. The major components of the cell wall are glucan and chitin, which are associated with structural rigidity, and mannoproteins. The protein component, including both mannoprotein and nonmannoproteins, comprises some 40 or more moieties. Wall proteins may differ in their expression, secretion, or topological location within the wall structure. Proteins may be modified by glycosylation (primarily addition of mannose residues), phosphorylation, and ubiquitination. Among the secreted enzymes are those that are postulated to have substrates within the cell wall and those that find substrates in the extracellular environment. Cell wall proteins have been implicated in adhesion to host tissues and ligands. Fibrinogen, complement fragments, and several extracellular matrix components are among the host proteins bound by cell wall proteins. Proteins related to the hsp70 and hsp90 families of conserved stress proteins and some glycolytic enzyme proteins are also found in the cell wall, apparently as bona fide components. In addition, the expression of some proteins is associated with the morphological growth form of the fungus and may play a role in morphogenesis. Finally, surface mannoproteins are strong immunogens that trigger and modulate the host immune response during candidiasis.
755 citations
TL;DR: Advances in carbohydrate chemistry have enabled us to move from the foundation of composition analysis to more rapid characterization of specific structures, which will lead to a greater understanding of how fungi coexist with their hosts as commensals or exist in conflict as pathogens.
Abstract: Although fungi have always been with us as commensals and pathogens, fungal infections have been increasing in frequency over the past few decades. There is a growing body of literature describing the involvement of carbohydrate groups in various aspects of fungal disease. Carbohydrates comprising the cell wall or capsule, or as a component of glycoproteins, are the fungal cell surface entities most likely to be exposed to the surrounding environment. Thus, the fungus-host interaction is likely to involve carbohydrates before DNA, RNA, or even protein. The interaction between fungal and host cells is also complex, and early studies using whole cells or crude cell fractions often produced seemingly conflicting results. What was needed, and what has been developing, is the ability to identify specific glycan structures and determine how they interact with immune system components. Carbohydrate analysis is complicated by the complexity of glycan structures and by the challenges of separating and detecting carbohydrates experimentally. Advances in carbohydrate chemistry have enabled us to move from the foundation of composition analysis to more rapid characterization of specific structures. This, in turn, will lead to a greater understanding of how fungi coexist with their hosts as commensals or exist in conflict as pathogens.
177 citations
TL;DR: A better understanding of the humoral response to cell wall antigens of C. albicans may provide the basis for the development of effective procedures for the serodiagnosis of disseminated candidiasis and novel prophylactic and therapeutic strategies for the management of this type of infection.
Abstract: The cell wall of Candida albicans not only is the structure in which many biological functions essential for the fungal cells reside but also is a significant source of candidal antigens. The major cell wall components that elicit a response from the host immune system are proteins and glycoproteins, the latter being predominantly mannoproteins. Both the carbohydrate and protein moieties are able to trigger immune responses. Although cell-mediated immunity is often considered to be the most important line of defense against candidiasis, cell wall protein and glycoprotein components also elicit a potent humoral response from the host that may include some protective antibodies. Proteins and glycoproteins exposed at the most external layers of the wall structure are involved in several types of interactions of fungal cells with the exocellular environment. Thus, coating of fungal cells with host antibodies has the potential to influence profoundly the host-parasite interaction by affecting antibody-mediated functions such as opsonin-enhanced phagocytosis and blocking the binding activity of fungal adhesins for host ligands. In this review, the various members of the protein and glycoprotein fraction of the C. albicans cell wall that elicit an antibody response in vivo are examined. Although a number of proteins have been shown to stimulate an antibody response, for some of these species the response is not universal. On the other hand, some of the studies demonstrate that certain cell wall antigens and anti-cell wall antibodies may be the basis for developing specific and sensitive serologic tests for the diagnosis of candidasis, particularly the disseminated form. In addition, recent studies have focused on the potential for antibodies to cell wall protein determinants to protect the host against infection. Hence, a better understanding of the humoral response to cell wall antigens of C. albicans may provide the basis for the development of (i) effective procedures for the serodiagnosis of disseminated candidiasis and (ii) novel prophylactic (vaccination) and therapeutic strategies for the management of this type of infection.
156 citations
TL;DR: In this paper, side chain oligosaccharides from mannans of Candida albicans NIH B-792 (serotype B) and Candida parapsilosis IFO 1396 strains were extracted by acetolysis under mild conditions.
Abstract: Isolation of side chain oligosaccharides from mannans of Candida albicans NIH B-792 (serotype B) and Candida parapsilosis IFO 1396 strains has been conducted by acetolysis under mild conditions. Structural study of these oligosaccharides by 1H and C NMR and methylation analyses indicated the presence of novel branched side chains with the following structures in C. albicans mannan.
127 citations
TL;DR: It was shown in the present 1H nuclear magnetic resonance study that an examination of chemical shifts not only in the H-1 region but also in theH-5 region was useful for the quantitative determination of the phosphate-bound beta-1,2-linked oligomannosyl residues.
Abstract: In previous articles, we reported the presence of phosphate-bound beta-1,2-linked oligomannosyl residues in the mannans of strains of Candida albicans serotypes A and B and Candida stellatoidea. To identify the antigenic factor corresponding to this type of oligomannosyl residue, a relationship between chemical structure and antigenic specificity in the mannans of C. albicans NIH B-792 (serotype B, B-strain) and C. albicans J-1012 (serotype A, J-strain) was investigated by using a combination of two-dimensional 1H nuclear magnetic resonance spectroscopy of H-1, H-2, and H-5 regions in the mannans and an enzyme-linked immunosorbent assay that employed concanavalin A-coated microtiter plates. It was shown in the present 1H nuclear magnetic resonance study that an examination of chemical shifts not only in the H-1 region but also in the H-5 region was useful for the quantitative determination of the phosphate-bound beta-1,2-linked oligomannosyl residues. In the enzyme-linked immunosorbent assay using concanavalin A-coated plates, it was revealed that, of factor sera 1, 4, and 5, only factor serum 5 showed a reactivity proportional to the densities of the beta-1,2-linked oligomannosyl residues of the mannan subfractions of different phosphate contents that had been prepared from the bulk B-strain mannan by DEAE-Sephadex chromatography. The above results indicate that the phosphate-bound beta-1,2-linked oligomannosyl residues, Manp beta 1----(2Manp beta 1----)n2Man (n = 0-5), correspond to antigenic factor 5.
116 citations
Cites background from "Structural study on a phosphorylate..."
...albicans also contains mannose-6-phosphate group (42), it is reasonable to expect that binding of C....
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...1-1,2-linked oligomannosyl residues in only phosphodiesterified form (21, 42), however, the determination by 1D NMR...
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...The phosphate-bound, acid-labile 1-1,2-linked oligomannosyl residues are common structures in serotypes A and B and might be responsible for the majority of humoral antibody responsiveness of the parent whole cells (21, 39, 42, 43, 47) because of their strong antigenicity and low crossreactivity with the constituents in mammals....
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...Figure 3E shows a 2D-HOHAHA spectrum of 13-1,2linked mannotetraose, corresponding to the major oligomannosyl residue of acid-labile side chains (19, 39, 40, 42) (Fig....
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References
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TL;DR: In this article, a method was developed to determine submicro amounts of sugars and related substances using a phenol-sulfuric acid reaction, which is useful for the determination of the composition of polysaccharides and their methyl derivatives.
Abstract: Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orangeyellow color w-hen treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.
45,381 citations
TL;DR: In this article, a new mixing scheme based on the MLEV-16 composite pulse decoupling cycle (II) was proposed, which is less sensitive to pulse imperfections and provides net magnetization transfer over a substantial bandwidth with only limited rf power.
Abstract: Recently, we have shown that net magnetization transfer among scalar coupled homonuclear spins can be obtained by the application of a spin-lock field (I), or more effectively, by the application of a phase-alternated spin-lock field (2, 3). Analogous methods to accomplish net homonuclear magnetization transfer, based on different rfirradiation schemes have previously been reported by Braunschweiler and Ernst (4). As they and others (5-9) have pointed out, the key to net magnetization transfer between two coupled spins, A and X, is to remove the Zeeman contributions, HzA and Hzx, from the Hamiltonian, or to make them identical, i.e., HzA = Hz,. This can be accomplished by suitable rf irradiation schemes or by zero-field NMR (JO). In this communication we describe a new mixing scheme that is based on the MLEV-16 composite pulse decoupling cycle (II). We have modified this cycle to make it less sensitive to pulse imperfections and it will be shown that this type of MLEV mixing provides net magnetization transfer over a substantial bandwidth with only limited rf power. More importantly, the apparent decay constant of spin-locked magnetization can be prolonged by up to a factor of two (compared to TIP) by using this new type of mixing scheme. If the Zeeman part of the Hamiltonian is eliminated, the spin system will evolve solely under the influence of scalar coupling. Magnetization can then propagate through the molecule in a way that is very similar to spin diffusion among protons in a rigid solid, where dipolar couplings are usually much larger than differences in chemical shift. For molecules consisting of only two coupled homonuclear spins, A and X, Braunschweiler and Ernst have shown that in the isotropic coupling limit there is an oscillatory exchange of the A and X magnetization, with period 1 /JAx. Explicit results for the AX2 case have very recently been presented by Chandrakumar and Subramanian (12). For larger spin systems a computer simulation program appears to be the easiest way to predict the rate at which magnetization will propagate through the molecule. AS demonstrated earlier (2), the net magnetization transfer obtained in this type of experiment permits the recording of phase-sensitive spectra, and gives in many cases enhanced resolution and sensitivity compared to the widely used COSY experiment (13-16). For short mixing times (<0.1/J), only direct connectivities will be observed. For longer mixing times, magnetization that has been transferred from spin A to spin M during the first part of the mixing period can be relayed to spin X during the second
3,552 citations
TL;DR: The cations of T4 phage have been examined and a balance has been obtained between total cations and total DNA anions and the replacement of the normal polyamines suggested that the polyamines may be acting as nonspecific cations.
Abstract: It was previously reported that bacteriophage T4 contains the polyamines putrescine, NH2(CH2)$;IH2, and spermidine, NHQ(CH&NH(CH&NH2, in amounts sufficient to neutralize about half of the viral deoxyribonucleic acid (1). The putrescine and spermidine in the phage were found to be derived from the large amount of these polyamines normally present in the host bacterium, Escherichia coli B. It was also shown that these cations are the unidentified compounds in phage T2 reported by Hershey to be injected into the bacteria along with the viral DNA (2). In the present communication we have attempted to answer certain questions raised by these findings: 1. Is the role of the polyamines in phage that of specific or nonspecific cations for neutralizing the negatively charged phosphate groups in the DNA? 2. Are the amounts and kinds of polyamines in the phage determined by the phage or by the bacterial pool of cations? 3. Can stoichiometry between cations in the phage and the phosphate anions of the DNA be demonstrated? 4. What is the distribution of polyamines in viruses? The cations of T4 phage have been examined and a balance has been obtained between total cations and total DNA anions. The normal cation content of T4 (putrescine++, spermiclme+++, and Mg++) was changed markedly under certain conditions. When the host bacterium E. coli B was grown on minimal medium contaming spermine, NH2(CH2)3NH(CH&NH(CH&NH~, a polyamine present in animal tissues (3, 4) but not generally present in bacteria (5), the putrescine and spermidine normally present in the E. coli were replaced by spermine and acetylated spermine (6). These abnormal polyamines were found as the main polyamines in the T4 phage grown on these bacteria. The replacement of the normal polyamines suggested that the polyamines may be acting as nonspecific cations. Two types of evidence support this hypothesis. The lack of polyamines in various bacteriophages (T3, T5, P22) has been correlated with the permeability of these phages to cations; it seems as if the polyamines were displaced by other cations during the purification of the phage. When Brenner’s (7) permeable (osmotic-shock resistant) mutant of T4 was washed with Mg++, a preparation of phage was obtained containing essentially no polyamines; when the mutant phage was washed with spermidine and then with water, a balance was obtained between the DNA anions and the spermidine cations. The properties of preparations of T4 phage containing various cations have been examined.
2,468 citations
TL;DR: The primary structure of human insulin-like growth factor II receptor, predicted from the complementary DNA sequence, reveals a transmembrane receptor molecule with a large extracellular domain made up of fifteen repeat sequences and a small region homologous to the collagen-binding domain of fibronectin.
Abstract: The primary structure of human insulin-like growth factor II receptor, predicted from the complementary DNA sequence, reveals a transmembrane receptor molecule with a large extracellular domain made up of fifteen repeat sequences and a small region homologous to the collagen-binding domain of fibronectin. The structural and biochemical features of the IGF-II receptor appear identical to those of the cation-independent mannose-6-phosphate receptor.
851 citations
TL;DR: Controlled acetolysis of yeast mannans yields mixtures of oligosaccharides with (1-->2) and (1 -->3) linkages between the mannose units, whereas the less stable linkages of the polysaccharide backbone are cleaved.
Abstract: Controlled acetolysis of yeast mannans yields mixtures of oligosaccharides with (1→2) and (1→3) linkages between the mannose units, whereas the less stable (1→6) linkages of the polysaccharide backbone are cleaved. The “fingerprints,” obtained by gel filtration of the oligosaccharide mixtures, can be used to distinguish between the different yeast mannans. The general method may be useful for determining the taxonomy of yeasts and for making correlations between immunochemical reactivity and mannan structure.
332 citations