A Fraction of the BglG Transcriptional Antiterminator from Escherichia coli Exists as a Compact Monomer

Liat Fux, Anat Nussbaum-Shochat, Orna Amster-Choder*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Expression of the bgl operon in Escherichia coli, induced by β-glucosides, is positively regulated by BglG, a transcriptional antiterminator. In the presence of inducer, BglG dimerizes and binds to the bgl transcript to prevent premature termination of transcription. The dimeric state of BglG is determined by BglF, a membrane-bound enzyme II of the phosphoenolpyruvate-dependent phosphotransferase system (PTS), which reversibly phosphorylates BglG according to β-glucoside availability. BglG is composed of an RNA-binding domain followed by two homologous PTS regulation domains (PRD1 and PRD2). The predicted structure of dimeric LicT, a BglG homologue from Bacillus subtilis, suggests that the two PRDs adopt a similar structure and that the interactions within the dimer are PRD1-PRD1 and PRD2-PRD2. We have shown recently that the PRD1 and PRD2 domains of BglG can form a stable heterodimer. We report here, based on in vitro and in vivo cross-linking experiments, that a fraction of BglG is present in the cell in a compact form in which PRD1 and PRD2 are in close proximity. The compact form is present mainly in the BglG monomers. Our results imply that the monomer-dimer transition involves a conformational change. The possible role of the compact form in preventing untimely induction of the bgl operon is discussed.

Original languageAmerican English
Pages (from-to)50978-50984
Number of pages7
JournalJournal of Biological Chemistry
Issue number51
StatePublished - 19 Dec 2003


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