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Signal transduction between a membrane‐bound transporter, PtsG, and a soluble transcription factor, Mlc, of Escherichia coli
Author(s) -
Lee SungJae,
Boos Winfried,
Bouché JeanPierre,
Plumbridge Jacqueline
Publication year - 2000
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/19.20.5353
Subject(s) - biology , marie curie , transcription (linguistics) , humanities , philosophy , linguistics , european union , business , economic policy
The global regulator Mlc controls several genes implicated in sugar utilization systems, notably the phosphotransferase system (PTS) genes, ptsG , manXYZ and ptsHI , as well as the malT activator. No specific low molecular weight inducer has been identified that can inactivate Mlc, but its activity appeared to be modulated by transport of glucose via Enzyme IICB Glc (PtsG). Here we demonstrate that inactivation of Mlc is achieved by sequestration of Mlc to membranes containing dephosphorylated Enzyme IICB Glc . We show that Mlc binds specifically to membrane fractions which carry PtsG and that excess Mlc can inhibit Enzyme IICB Glc phosphorylation by the general PTS proteins and also Enzyme IICB Glc ‐mediated phosphorylation of α‐methylglucoside. Binding of Mlc to Enzyme IICB Glc in vitro required the IIB domain and the IIC–B junction region. Moreover, we show that these same regions are sufficient for Mlc regulation in vivo , via cross‐dephosphorylation of IIB Glc during transport of other PTS sugars. The control of Mlc activity by sequestration to a transport protein represents a novel form of signal transduction in gene regulation.