Biogenesis and metabolic significance of microbodies in urate-utilizing yeasts

Abstract

Growth of Candida famata and Trichosporon cutaneum on uric acid as the sole source of carbon and nitrogen was associated with the development of a number of microbodies in the cells. Cytochemical staining experiments showed that the organelles contained urate oxidase, a key enzyme of uric acid metabolism, and catalase. Transfer of cells, precultured on glucose or glycerol, into uric acid-containing media indicated that these microbodies originated from the organelles, originally present in the inoculum cells, by growth and division. In urate-grown C. famata the microbodies were frequently observed in large clusters; in both organisms they existed in close association with mitochondria and strands of ER. The organelles lacked crystalline inclusions. In freeze-fractured cells their surrounding membranes showed smooth fracture faces. Exposure of urate-grown cells to glucose-excess conditions led to a rapid inactivation of urate oxidase activity but catalase was only slightly inactivated. Glucose-induced enzyme inactivation was not associated with the degradation of the microbodies present in the cells. Similarly, repression of urate oxidase synthesis by ammonium ions also did not lead to the degradation of peroxisomes.

Evidence for functional heterogeneity among microbodies in yeasts

“…Depending on the final composition of the cultivation medium, organelles may develop which can be involved in the metabolism of the carbon source Fukui and Tanaka 1979;Veenhuis and Harder 1988), the nitrogen source (Zwart Offprint requests to: M. Veenhuis 1983) or both (Zwart et al 1980;Veenhuis et al 1985Veenhuis et al , 1986.…”

Subcellular location of the enzymes of purine breakdown in the yeast Candida famata grown on uric acid

“…which can be used as the combined carbon and nitrogen source for growth [5]. This growth is accompanied by proliferation of microbodies (peroxisomes), which were shown by cytochemical staining to contain uricase [6]. However, the location of the other key enzymes of uric acid breakdown is unknown and is the subject of the present report.…”

“…Cells pregrown on 0.5% (w/v) glu-0378-1097/90/$03.50 © 1990 Federation of European Microbiological Societies cose were shifted to fresh medium containing 17o (w/v) uric acid as combined carbon and nitrogen source and incubated at 30°C; growth was measured as described [6]. Cells were harvested at OD660 = 1.4, when the uric acid had just finally been used up.…”

“…Cell free extracts were prepared as described [6]. Uricase was assayed as described previously [6] with Tris buffer replaced by 0.1 M borate (pH 8.0); allantoinase and allantoicase were determined by the method of Takada and Noguchi [8] and ureidoglycollate lyase as described by Takada and Tsukiji [4] (prior to the ureidoglycollate lyase assay the cell free extract was incubated for 5 min with 2 mM MnCI2).…”

“…Uricase was assayed as described previously [6] with Tris buffer replaced by 0.1 M borate (pH 8.0); allantoinase and allantoicase were determined by the method of Takada and Noguchi [8] and ureidoglycollate lyase as described by Takada and Tsukiji [4] (prior to the ureidoglycollate lyase assay the cell free extract was incubated for 5 min with 2 mM MnCI2). Catalase and cytochrome c oxidase were determined as described by Douma et al [9]; malate synthase and isocitrate lyase by the method of Dixon and Kernberg [10].…”