Phenotypic Resistance to Amphotericin B in Candida albicans: Relationship to Glucan Metabolism

Notario, Vicente; Gale, E. F.; Kerridge, D.; Wayman, Frances J.

doi:10.1099/00221287-128-4-761

Cited by 13 publications

(18 citation statements)

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“…The activity on laminarin determined in organisms rendered permeable by toluene treatment (Notario et al, 1982), was also enhanced (by up to 47%) by 2-deoxy-~-glucose within the range from 0.3 to 3 mM. Under these same assay conditions 0.3 mM-D-allose produced a 50% inhibition of the activity on laminarin, but the inhibition decreased at higher concentrations (22 % at 1 mM).…”

mentioning

confidence: 68%

“…If similar linkages exist in the walls of C. albicans, the effects of chitinase on autolysis and on the P-glucanase activities of intact organisms (Notario et al, 1982) could be due to an indirect action on enzymes bound to those glucan-chitin complexes.…”

Section: Discussionmentioning

confidence: 99%

“…The extent of activation was never higher than 25 %, whereas in crude extracts stimulations of about 100 to 200% could be attained (Notario et al, 1982). N-Ethylmaleimide (1 mM) inhibited the activity of both purified enzymes (29 % for enzyme I and 12 % for enzyme 11) after 60 min treatment, but the extent of inhibition was much smaller than that found with crude extracts (Notario et al, 1982).…”

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-Glucanases from Candida albicans: Purification, Characterization and the Nature of their Attachment to Cell Wall Components

Notario

1982

Microbiology

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P-Glucanase activities were found associated with Candida albicans and their culture fluids. Mild acid treatment of the organisms led to rapid inactivation of P-glucanase activities, the degree of loss increasing with the age of the cultures; the results suggested an extracytoplasmic location of the cell-associated enzymes. Most of the P-glucanase activities were associated with the cell walls in organisms phenotypically resistant to amphotericin B methyl ester (AME).Two proteins (I and 11) exhibiting P-glucanase activity were isolated and purified by conventional procedures from cell-free extracts, cell-wall autolysates and culture fluids of C. albicans sensitive and phenotypically resistant to AME. The purified enzymes appeared homogeneous on isoelectric focusing, gel electrophoresis and ultracentrifugation, with molecular weights of 150 000 (I) and 49 000 (11). Both enzymes hydrolysed cell walls purified from AME-sensitive and phenotypically resistant organisms, but showed different substrate specificities and patterns of activity. Enzyme I1 hydrolysed (1 -, 3)-P-glucans by an endolytic mechanism releasing laminaritetraose as the initial product. Glucose was the only product released by enzyme I. The properties of the individual enzymes were unaffected by their localization or the age of the culture of the organisms.The loosening of the polysaccharide packing by ultrasonic treatment of cell walls purified from AME-resistant organisms increased the P-glucanase activities bound to the walls, but did not solubilize them. Autolysis of cell walls released 58 to 66% of their P-glucanase activity in 20 h, but no further release was attained on prolonged incubation. The amount of P-glucanase activity released by autolysis was increased by a variety of pretreatments. Diethyl pyrocarbonate inhibited Pglucanase activity and prevented autolysis. Evidence is presented indicating that interactions with lipids, polysaccharides and other cell wall proteins may be involved in the control of the activity of the cell wall-associated P-glucanases in organisms phenotypically resistant to AME. I N T R O D U C T I O NA disequilibrium between the synthesis of the cell-wall P-glucan and its breakdown by endogenous P-glucanases seems to underlie the onset and development of phenotypic resistance to amphotericin B methyl ester (AME) in Candida albicans. In resistant organisms (cultures in the stationary phase of growth) most of the P-glucanase activity was found in a latent form bound to the cell wall, and could be activated by a number of treatments (SH-reducing agents, partial enzymic digestion of the walls, reduced aeration of the cultures) which simultaneously decreased the resistance of the organisms to the antibiotic. Other t Present address:

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-Glucanases from Candida albicans: Purification, Characterization and the Nature of their Attachment to Cell Wall Components

Notario

1982

Microbiology

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“…Details of growth, measurement of culture density, determination of the incorporation of radioactivity from labelled substrates into cultures or suspensions of organisms, assay of P-glucanase activities, sources of reagents, enzymes and labelled substrates were as described by Notario et al (1982).…”

Section: E T H O D Smentioning

confidence: 99%

“…In addition to those listed by Notario et al (1982), 2-deoxy-~-glucose 6-phosphate and phosphoglucomutase were purchased from Sigma.…”

Section: E T H O D Smentioning

confidence: 99%

The Action of 2-Deoxy-D-glucose on the Incorporation of Glucose into (1->3)- -Glucan in Stationary Phase Cultures of Candida albicans

Gale¹,

Wayman²,

Orlean³

1984

Microbiology

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2-Deoxy-~-glucose added to cultures of Candida albicans in the stationary phase of growth inhibited the incorporation of glucose into the (1-+3)-P-glucan fraction of the organisms. In the presence of ATP and cell extracts it was converted to 2-deoxy-~-glucose phosphate and when UTP was also present, material with the electrophoretic properties of UDP-2-deoxy-~-glucose was formed. In similar conditions glucose formed glucose phosphates, U DP-glucose and other products. Evidence was obtained that the analogue, after conversion to a phosphate derivative, was an inhibitor of phosphoglucomutase.When C. albicans was grown in the presence of 2-deoxy-~-glucose for 24 h, analogue residues became incorporated into the (1 +3)-P-glucan fraction and the subsequent rate of incorporation of glucose into that fraction was enhanced. The rate of turnover of glucose in this P-glucan fraction was greater than in controls. Pretreatment of cultures with P-glucanase, or incubation under conditions known to stimulate endogenous prglucanases, increased the subsequent rate of glucose incorporation and this increase was enhanced by growth in the presence of 2-deoxy-~-glucose. The analogue thus had the effect of altering the stability and glucose-acceptor function of (1-+3)-l)-glucan chains. This could affect the properties of the polymer network leading to the known effect of the analogue in delaying the onset of phenotypic resistance to amphotericin methyl ester in stationary phase cultures of C. albicans.

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Biosynthesis of Plant Cell Wall and Related Polysaccharides by Enzymes of the GT2 and GT48 Families

Stone

Jacobs

Hrmová

et al. 2010

Annual Plant Reviews

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In this chapter we outline the evolution of our understanding of the biological functions, genetics and regulation of enzymes of the GT2 and GT48 families of glycosyl transferases. The GT2 family is very large and includes enzymes encoded by the cellulose synthase gene superfamily, together with many other transferases with diverse substrate specifi cities that are distributed from the Archaea to humans. On the other hand, there are relatively few known members of the GT48 family, in which activities are limited to putative (1,3) -β -d -glucan synthases of embryophytes, fungi and yeasts. The review is focused on a number of individual case studies, which have been chosen on the basis of their biological and economical importance in plant biology. The history of our knowledge of (1,4) -β -d -glucan (cellulose) synthases and (1,3;1,4) -β -d -glucan synthases in plants will be reviewed as representatives of the GT2 family, while the (1,3) -β -d -glucan (or callose) synthases will be compared with these, as representatives of the GT48 family. These synthases have been extensively studied using biochemical techniques, but they are associated with membranes and are not easily purifi ed. Emerging functional genomics technologies have been used to identify the genes encoding the cellulose synthases of the GT2 family, while new proteomics

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Phenotypic Resistance to Amphotericin B in Candida albicans: Relationship to Glucan Metabolism

Cited by 13 publications

References 14 publications

-Glucanases from Candida albicans: Purification, Characterization and the Nature of their Attachment to Cell Wall Components

-Glucanases from Candida albicans: Purification, Characterization and the Nature of their Attachment to Cell Wall Components

The Action of 2-Deoxy-D-glucose on the Incorporation of Glucose into (1->3)- -Glucan in Stationary Phase Cultures of Candida albicans

Biosynthesis of Plant Cell Wall and Related Polysaccharides by Enzymes of the GT2 and GT48 Families

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