Nutrient restriction and metabolism

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Hi All,

See the introduction and abstract, which is not yet in Medline, is available as

a

pdf suggesting that, for cell

growth, CRing yeast throws the cell metabolism into energy-specific " whack " :

" genes

specifying functions associated with energy and metabolism tend to be expressed

with

exceptionally robust periodicity. "

This week in Science 2004

Science 310 (5751) 1087-1088

edited by Stella Hurtley and Phil Szuromi

Cycles Underlying Growth

Cultures of the budding yeast Saccharomyces cerevisiae that are grown in limited

nutrients, rather than in rich media more common in the lab, will show 4- to

5-hour

cycles of respiration, as measured by O2 consumption. Tu et al. (p. 1152,

published

online 27 October) found that under these conditions, more than half of the

yeast

genes are transcribed cyclically with a period of 300 minutes. Three large

clusters

of genes with related functions cycled together. The " oxidative cluster, " which

peaked when respiration was greatest, contains genes with roles related to

protein

synthesis, perhaps to make use of the high levels of adenosine triphosphate

readily

available at that time. The second supercluster, the " reductive/building " phase,

contained many components of DNA replication and cell division, and the third

" reductive/charging " group of genes contributed to nonrespiratory metabolism and

protein degradation.

Logic of the Yeast Metabolic Cycle: Temporal Compartmentalization of Cellular

Processes

P. Tu, Andrzej Kudlicki, Maga Rowicka, and L. McKnight

Science 18 November 2005: 1152-1158.

Budding yeast grown under continuous, nutrient-limited conditions exhibit

robust,

highly periodic cycles in the form of respiratory bursts. Microarray studies

reveal

that over half of the yeast genome is expressed periodically during these

metabolic

cycles. Genes encoding proteins having a common function exhibit similar

temporal

expression patterns, and genes specifying functions associated with energy and

metabolism tend to be expressed with exceptionally robust periodicity. Essential

cellular and metabolic events occur in synchrony with the metabolic cycle,

demonstrating that key processes in a simple eukaryotic cell are

compartmentalized

in time.

Al Pater, PhD; email: old542000@...

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