Editors' ChoiceCell Biology

Better Is Not Always Best

Science Signaling  13 Dec 2011:
Vol. 4, Issue 203, pp. ec346
DOI: 10.1126/scisignal.4203ec346

Once a cell has evolved a high-affinity transporter for nutrients like phosphate or zinc, why would it need to continue to make low-affinity transporters as well? Levy et al. address this question in yeast and show that the lower-affinity form does come in handy. When nutrients are plentiful, the low-affinity transporter is expressed and works fine. As nutrient concentrations are depleted, the low-affinity transporter begins to lose efficiency and the nutrient influx dips. This signals the cell to begin preparation for starvation—at a time earlier than it would have, if it had waited until nutrient concentrations got so low that function of the high-affinity transporter became compromised. Sensing a decrease in nutrient supply before concentrations get low enough to inhibit growth thus appears to be a key reason for expressing transporters of both low and high affinity.

S. Levy, M. Kafri, M. Carmi, N. Barkai, The competitive advantage of a dual-transporter system. Science 334, 1408–1412 (2011). [Abstract] [Full Text]