TY - JOUR T1 - Invariant Distribution of Promoter Activities in Escherichia coli A1 - Zaslaver, Alon A1 - Kaplan, Shai A1 - Bren, Anat A1 - Jinich, Adrian A1 - Mayo, Avi A1 - Dekel, Erez A1 - Alon, Uri A1 - Itzkovitz, Shalev Y1 - 2009/10/23 N2 - Author Summary Cells respond to a changing environment by regulating the activity of genes. Here, we sought to understand how E. coli cells distribute their limited transcriptional resources among their target genes, and how this allocation varies with growth rate and growth conditions. To achieve this, we assayed the expression of a comprehensive library of transcriptional reporter strains under different conditions. High-temporal resolution measurements of promoter activities were obtained for different growth rates spanning recovery from stationary phase into exponential phase and eventually deep stationary phase again. We find that the genome-wide promoter activity follows a power-law distribution, which depends solely on growth rate and is independent of the specific growth conditions. Moreover, we find that the power-law distribution can be decomposed into two log-normal distributions: metabolic promoters that make up the low end of the distribution, and ribosomal promoters that make up the high end of the distribution. While distributions remained constant for a given growth rate, the ranked expression of metabolic promoters differed according to the specific condition. Thus, the invariant distribution may suggest optimal resource allocation under constrained resources. A mathematical theory is presented to explain these results. JF - PLOS Computational Biology JA - PLOS Computational Biology VL - 5 IS - 10 UR - https://doi.org/10.1371/journal.pcbi.1000545 SP - e1000545 EP - PB - Public Library of Science M3 - doi:10.1371/journal.pcbi.1000545 ER -