FIGURE 4:

Remodeling of the transcriptome in response to relief from nitrogen limitation. (A) We clustered global gene expression data for cultures limited for proline and glutamine grown at different growth rates with gene expression profiles for ammonium-limited cultures transiently perturbed by the addition of 80 and 800 μM proline or 40 and 400 μM glutamine or a mixture of 20 μM glutamine and 40 μM proline. Many transcripts that increase (red bar) or decrease (green bar) systematically with growth rate in steady-state chemostats are also altered in expression when transiently relieved from nitrogen limitation. Average response of the NCR-A, NCR-P, GAAC, SPS, and UPR regulons to a (B) large or (C) small pulse of glutamine or a (D) large or (E) small pulse of proline. Gene expression values are relative to gene expression in an ammonium-limited chemostat growing at a dilution rate of 0.12 h⁻¹.