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Black and white with some shades of grey: the diverse responses of inducible metabolic pathways in E scherichia coli
Author(s) -
Rao Christopher V.,
Koirala Santosh
Publication year - 2014
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.12734
Subject(s) - lactose , biology , escherichia coli , lac operon , metabolic pathway , biochemistry , gene , galactose , beta galactosidase , mutant , genetics
Summary The metabolic pathways for many sugars are inducible. This process has been extensively studied in the case of E scherichia coli lactose metabolism. It has long been known that gratuitous induction of the lac operon with non‐metabolizable lactose analogues generates an all‐or‐nothing response, where some cells express the lac genes at a maximal rate and others not at all. However, the response to lactose itself is graded, where all cells express the lac genes in proportion to lactose concentrations. The mechanisms generating these distinct behaviours in lactose metabolism have been a topic of many studies. Despite this large body of work, little is known about how other pathways respond to their cognate sugars. An article of M olecular M icrobiology investigated the response of eight metabolic pathways in E . coli to their cognate sugars at single‐cell resolution. The authors demonstrate that these pathways exhibit diverse responses, ranging from graded to all‐or‐nothing responses and combinations thereof. Remarkably, they were able to interpret these responses using a simple mathematical model and identify the mechanisms likely giving rise to each.