Economics of membrane occupancy and respiro-fermentation
Artikel i vetenskaplig tidskrift, 2011

The simultaneous utilization of efficient respiration and inefficient fermentation even in the presence of abundant oxygen is a puzzling phenomenon commonly observed in bacteria, yeasts, and cancer cells. Despite extensive research, the biochemical basis for this phenomenon remains obscure. We hypothesize that the outcome of a competition for membrane space between glucose transporters and respiratory chain (which we refer to as economics of membrane occupancy) proteins influences respiration and fermentation. By incorporating a sole constraint based on this concept in the genome-scale metabolic model of Escherichia coli, we were able to simulate respirofermentation. Further analysis of the impact of this constraint revealed differential utilization of the cytochromes and faster glucose uptake under anaerobic conditions than under aerobic conditions. Based on these simulations, we propose that bacterial cells manage the composition of their cytoplasmic membrane to maintain optimal ATP production by switching between oxidative and substrate-level phosphorylation. These results suggest that the membrane occupancy constraint may be a fundamental governing constraint of cellular metabolism and physiology, and establishes a direct link between cell morphology and physiology.

expression

constraint-based modeling

evolution

oxidase

yield

overflow metabolism

growth-conditions

saccharomyces-cerevisiae

membrane occupancy

flux balance analysis

microbial-populations

respiro-fermentation

overflow metabolism

reconstruction

escherichia-coli

Författare

K. Zhuang

University of Toronto

Goutham Vemuri

Kemi- och bioteknik, Livsvetenskaper, Systembiologi

R. Mahadevan

University of Toronto

Molecular Systems Biology

1744-4292 (ISSN)

Vol. 7 500

Ämneskategorier

Biokemi och molekylärbiologi

DOI

10.1038/msb.2011.34