Detection of intracellular forms of secretory aspartic proteinase in Candida albicans

Homma, Michio; Kanbe, Toshio; Chibana, Hiroji; Tanaka, Kenji

doi:10.1099/00221287-138-3-627

Cited by 23 publications

(30 citation statements)

References 30 publications

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“…The mechanism of C. albicans Sap secretion into the extracellular environment is thought to be similar to that of other secreted proteins [27,28]. The data from the current study suggest that the adverse effects of lysozyme may be on the cell membrane, thereby hampering the Sap secretory process and leading to its intracellular accumulation.…”

Section: Discussionmentioning

confidence: 62%

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Inhibition of Growth and Secreted Aspartyl Proteinase Production in Candida Albicans by Lysozyme

Samaranayake

Leung

et al. 1999

Journal of Medical Microbiology

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Lysozyme (muramidase) is a non-specific, antimicrobial protein ubiquitous in human mucosal secretions such as saliva. Although its antibacterial and antifungal activities are well recognised, there are no data on the specific concentrations necessary to affect the growth of Candida albicans or about the effect of lysozyme on the production of secreted aspartyl proteinase (Sap), a putative virulence factor of C. albicans. Five Sap-producing isolates of C. albicans were cultured in YCB-BSA medium with various concentrations of lysozyme to examine its effect on yeast cell growth, ultrastructural cellular topography and extracellular and intracellular Sap concentration and activity. Lysozyme was candidacidal at high concentrations and decreased significantly the extracellular Sap concentration at sublethal doses, accompanied by intracellular accumulation of the enzyme. At low concentrations of lysozyme (c. lOpg/ml), Sap activity decreased more than two-fold and Sap concentration decreased five-fold without any appreciable effect on cell growth or viability. Ultrastructural investigations showed ballooned cells and cells with invaginations (expecially present near bud scars), indicating that cell-wall components may be possible targets for this enzyme. All concentrations of lysozyme tested were well within physiologically attainable levels. These data suggest that lysozyme has, at least, a bimodal action on C. albicans, killing the organism at higher concentrations and modulating Sap metabolism at lower concentrations.

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Section: Discussionmentioning

confidence: 62%

“…wt in SDS-PAGE has been reported variously as 42-48 kDa [5,31]. Furthermore, the open reading frames of the Sap iso-enzymes encode pre-proproteins which are processed during secretion [28]. This could account for the 45-kDa species detected in the present study.…”

Section: Discussionmentioning

confidence: 62%

Inhibition of Growth and Secreted Aspartyl Proteinase Production in Candida Albicans by Lysozyme

Samaranayake

Leung

et al. 1999

Journal of Medical Microbiology

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“…Affinity purification of the anti-EPR antibodies was performed with purified secreted EPR (Homma et al, 1992) coupled to CNBr-activated Sepharose 4B (Phannacia). Eluate of affinity chromatography was concentrated with the aid of a microdialyser (Ultrafree-PF; Millipore).…”

Section: Methodsmentioning

confidence: 99%

Ultrastructure of proteinase-secreting cells of Candida albicans studied by alkaline bismuth staining and immunocytochemistry

Akashi

Homma

Kanbe

et al. 1993

Journal of General Microbiology

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The ultrastructure of Cundida ulbicans cells induced to secrete extracellular proteinase (EPR) has been studied. Electron microscopy employing alkaline bismuth staining, a method which stains polysaccharides, clearly revealed Golgi-like bodies and secretory vesicles in C. albicans cells. After EPR induction, there was no apparent increase in the number of these structures. Instead, many flocculent granules appeared at the periphery of induced cells. The granules were similar to secretory vesicles in size, but were more irregular in shape. Similar granules were observed in non-induced cells, though less frequently than in induced cells. Brefeldin A, a specific inhibitor of membrane transport in the secretory pathway, caused the accumulation of EPR and Golgi-like bodies in EPR-induced cells, but did not affect the accumulation of the granules, These results suggest that the granules are unrelated to EPR secretion. Electron microscope immunocytochemistry with affinity-purified anti-EPR antibodies showed that the granules in EPR-induced cells were recognized by the antibodies. This recognition was completely inhibited by the presence of glycogen, suggesting that antibodies cross-react with glycogen-like polysaccharides in the granules. Although the location of EPR within the cells remains unclear, the results suggest that EPR might be secreted via the constitutive secretory pathway, and that EYR is glycosylated to give a structure with some similarity to glycogen.

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“…EPR digests various substrates, such as bovine haemoglobin, BSA, human stratum corneum and others . It is induced in minimal medium containing protein as a sole nitrogen source (EPR induction medium) ; however, low molecular mass nitrogen sources, such as amino acids or ammonium sulphate, repress EPR production (Banerjee et al, 1991 ;Homma et al, 1992;Ross et al, 1990). Glucose also affects the degree of EPR production (Crandall & Edwards, 1987;Samaranayake et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

Induction of extracellular proteinase in Candida albicans

Homma

Chibana

Tanaka

1993

Journal of General Microbiology

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Pulse-chase experiments indicated that the extracellular proteinase (EPR) of Candida albicans originates as a 45 kDa precursor protein which is processed to a 43 kDa protein prior to secretion. Secretion was routinely stimulated in EPR induction medium which contains bovine serum albumin (BSA) and glucose. Although EPR was not induced without glucose as a carbon source, EPR secretion was induced without the addition of BSA or other nitrogen sources. Furthermore, it was shown that EPR production was not induced at pH > 6.0, irrespective of the presence of a nitrogen source. This suggests that medium pH may act directly upon EPR induction, and not as a secondary effect of the nitrogen supply from EPR-mediated protein digestion, which exhibited a pH optimum of around pH 3.5. When germ tube induced cells were transferred to EPR induction medium, EPR was not induced. Thus, EPR production and germ tube formation may not be induced by the same conditions. We speculate that EPR production and germ tube formation do not co-operate in the invasive process but play different and separate roles.

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Detection of intracellular forms of secretory aspartic proteinase in Candida albicans

Cited by 23 publications

References 30 publications

Inhibition of Growth and Secreted Aspartyl Proteinase Production in Candida Albicans by Lysozyme

Inhibition of Growth and Secreted Aspartyl Proteinase Production in Candida Albicans by Lysozyme

Ultrastructure of proteinase-secreting cells of Candida albicans studied by alkaline bismuth staining and immunocytochemistry

Induction of extracellular proteinase in Candida albicans

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