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The effects of DNA supercoiling on the expression of operons of the ilv regulon of Escherichia coli suggest a physiological rationale for divergently transcribed operons
Author(s) -
Opel Michael L.,
Arfin Stuart M.,
Hatfield G. Wesley
Publication year - 2001
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/j.1365-2958.2001.02309.x
Subject(s) - operon , regulon , dna supercoil , biology , promoter , transcription (linguistics) , genetics , dna , escherichia coli , rna polymerase , gene , transcriptional regulation , regulation of gene expression , gene expression , dna replication , linguistics , philosophy
Transcriptional activities of closely spaced divergent promoters are affected by the accumulation of local negative superhelicity in the region between transcribing RNA polymerase molecules (transcriptional coupling). The effect of this transcription‐induced DNA supercoiling on these promoters depends on their intrinsic properties. As the global superhelical density of the chromosome is controlled by the energy charge of the cell, which is affected by environmental stresses and transitions from one growth state to another, the transcriptional coupling that occurs between divergently transcribed promoters is likely to serve a physiological purpose. Here, we suggest that transcriptional coupling between the divergent promoters of the ilvYC operon of Escherichia coli serves to co‐ordinate the expression of this operon with other operons of the ilv regulon during metabolic adjustments associated with growth state transitions. As DNA supercoiling‐dependent transcriptional coupling between the promoters of other divergently transcribed operons is investigated, additional global gene regulatory mechanisms and physiological roles are sure to emerge.