Endogenous respiration reflects the energy load imposed by transport of nonmetabolizable substrates and by induced de novo protein synthesis in Rhodotorula glutinis |
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Authors: | S Janda K Sigler M Höfer |
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Institution: | (1) Institute of Microbiology, Czechoslovak Academy of Sciences, Víde ská 1083, 14220 Prague 4, Czech Republic;(2) Bolanisches Institut der Universität Bonn, Kirschallee 1, W-5300 Bonn 1, Germany |
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Abstract: | Uptake of the nonmetabolizable sugars 6-deoxy-d-glucose, l-rhamnose and l-xylose, which are taken up by a common carrier, stimulated significantly cell respiration in Rhodotorula glutinis. The extra oxygen consumption for uptake (0.5–0.7 equivalents O2/mol transported sugar) was proportional to the uptake rate and was independent of the K
tvalue of the transport system. Sugars that become metabolized after induction, d-arabinose and methyl- -d-glucoside, caused a higher stimulation, 1.4 and 3.6 equivalents O2/mol respectively, which was reduced to 0.6 equivalents O2/mol when de novo protein synthesis was blocked by cycloheximide. The stimulation of respiration thus includes a fraction related purely to the energy demand for uptake and another one related to the induced de novo protein synthesis. The net uptake-induced respiration boost was similar with all sugars under study irrespective of their transport systems. The estimated energy demand was equivalent to about 2 ATP/sugar molecule. For comparison, the amino acid analogue -aminoisobutyric acid (AIB) was also investigated; the overall energy demand for its uptake corresponded to the equivalent of about 4 ATP/molecule.Abbreviation AIB
-aminoisobutyric acid |
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Keywords: | Substrate uptake Energy requirement Endogenous respiration Nonmetabolized substrate Induced catabolism Rhodotorula glutinis |
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