title: Activity of Lac repressor anchored to the Escherichia coli inner membrane.
abstract: The transient inactivation of gene regulatory proteins by their sequestration to the cytoplasmic membrane in response to cognate signals is an increasingly recognized mechanism of gene regulation in bacteria. It remained to be shown, however, whether tethering to the membrane per se could be responsible for inactivation, i.e. whether such relocation leads to a spatial separation from the chromosome that results in inactivity or whether other mechanisms are involved. We, therefore, investigated the activity of Lac repressor artificially attached to the Escherichia coli cytoplasmic membrane. We demonstrate that this chimeric protein perfectly represses transcription initiated at the tac operator-promoter present on a plasmid and even in the chromosome. Moreover, this repression is inducible as normal. The data suggest that proteins localized to the inner face of the cytoplasmic membrane in principle have unrestricted access to the chromosome. Thus sequestration to the membrane in terms of physical separation from the chromosome cannot account alone for the inactivation of regulatory proteins. Other mechanisms, like induction of a conformational change or masking of binding domains are required additionally.
authors.affiliation: Institut für Biologie III, Universität Freiburg Schänzlestrasse 1, D-79104 Freiburg, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Görke
authors.forename: Jana
authors.initials: J
authors.lastname: Reinhardt
authors.forename: Bodo
authors.initials: B
authors.lastname: Rak
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002876:Chromosomes, Bacterial; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D007700:Kinetics; D056968:Lac Repressors; D008565:Membrane Proteins / Q000032:analysis / Q000378:metabolism*; D009875:Operator Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000032:analysis / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D056968:Lac Repressors; C539064:LacI protein, E coli; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins