This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Articles by ter Kuile, B H Articles by Opperdoes, F R Search for Related Content PubMed PubMed Citation Articles by ter Kuile, B H Articles by Opperdoes, F R

 Previous Article  |  Next Article 

J Bacteriol. 1992 February; 174(4): 1273-1279

research-article

Mutual adjustment of glucose uptake and metabolism in Trypanosoma brucei grown in a chemostat.

Research Unit for Tropical Diseases, International Institute for Cellular and Molecular Pathology, Brussels, Belgium.

ABSTRACT

The mutual adjustment of glucose uptake and metabolism in the insect stage of the protozoan parasite Trypanosoma brucei was studied. T. brucei was preadapted in the chemostat to conditions in which either glucose or proline served as the major carbon and energy source. Cells were grown and adapted to either energy or non-energy limitation at a low dilution rate (0.5 day-1) or a high dilution rate (1 day-1). The cells were then used in short- to medium-term uptake experiments with D-[14C]glucose as a tracer. In time course experiments a steady state was reached after 15 min regardless of the preadaptation conditions. This steady-state level increased with increasing glucose availability during preadaptation. The rate of glucose uptake and the hexokinase activity were linearly correlated. In short-term 5- to 90-s) uptake experiments a high transport rate was measured with cultures grown in excess glucose, an intermediate rate was measured with proline-grown cultures, and a low rate was measured in organisms grown under glucose limitation. Glucose metabolism and proline metabolism did not affect each other during the 15-min incubations. Glucose uptake, as a function of the external glucose concentration, did not obey simple Michaelis-Menten kinetics but could be described by a two-step mechanism: (i) transport of glucose by facilitated diffusion and (ii) subsequent metabolism of glucose. The respective rates of the two steps were adjusted to each other. It is concluded that T. brucei is capable of adjusting the different metabolic processes in a way that gives maximum energy efficiency at the cost of short-term flexibility.