Open AccessPromoters maintain their relative activity levels under different growth conditions
Author(s) -
Keren Leeat,
Zackay Ora,
LotanPompan Maya,
Barenholz Uri,
Dekel Erez,
Sasson Vered,
Aidelberg Guy,
Bren Anat,
Zeevi Danny,
Weinberger Adina,
Alon Uri,
Milo Ron,
Segal Eran
Publication year - 2013
Publication title -
molecular systems biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 8.523
H-Index - 148
ISSN - 1744-4292
DOI - 10.1038/msb.2013.59
Subject(s) - promoter , biology , scaling , gene expression , regulation of gene expression , computational biology , expression (computer science) , genetics , gene , mathematics , computer science , geometry , programming language
Most genes change expression levels across conditions, but it is unclear which of these changes represents specific regulation and what determines their quantitative degree. Here, we accurately measured activities of ∼900 S. cerevisiae and ∼1800 E. coli promoters using fluorescent reporters. We show that in both organisms 60–90% of promoters change their expression between conditions by a constant global scaling factor that depends only on the conditions and not on the promoter's identity. Quantifying such global effects allows precise characterization of specific regulation—promoters deviating from the global scale line. These are organized into few functionally related groups that also adhere to scale lines and preserve their relative activities across conditions. Thus, only several scaling factors suffice to accurately describe genome‐wide expression profiles across conditions. We present a parameter‐free passive resource allocation model that quantitatively accounts for the global scaling factors. It suggests that many changes in expression across conditions result from global effects and not specific regulation, and provides means for quantitative interpretation of expression profiles.