ISSN:
1432-072X
Keywords:
Substrate uptake
;
Energy requirement
;
Endogenous respiration
;
Nonmetabolized substrate
;
Induced catabolism
;
Rhodotorula glutinis
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
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-α-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 α-aminoisobutyric acid (AIB) was also investigated; the overall energy demand for its uptake corresponded to the equivalent of about 4 ATP/molecule.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00249033
