Cell Biology

Gained in the Translation

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Science  20 Jan 2012:
Vol. 335, Issue 6066, pp. 264
DOI: 10.1126/science.335.6066.264-c

Natural selection favors cells or organisms that are able to adapt quickly and effectively to changes in their environment. Baumgartner et al. report new insights into such regulation in a relatively simple system in which yeast cells growing in medium containing galactose respond to the presence of glucose by decreasing the half-life of mRNA encoding the GAL1 protein, which functions in conversion of galactose to glucose 6-phosphate. By following responses of individual cells in a microfluidic device that was used to change the medium around the cells, they showed that the decreased abundance of GAL1 mRNA was critical for signaling to cells to increase their growth rate in response to abundant glucose. Total amounts of mRNA in the cell did not change. Instead, GAL1 mRNA and the cyclin CLN3, whose translation promotes cell division, competed for access to a localized pool of ribosomes or other components of the translation machinery. Reciprocally, enhanced translation of CLN3 was detrimental to production of GAL1 when cells were grown in galactose. Thus, removal of excess transcripts is an important component that allows yeast cells to optimize growth rates in a glucose-rich environment.

Proc. Natl. Acad. Sci. U.S.A. 108, 21087 (2011).

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