CIRCE is not involved in heat-dependent transcription of groESL but in stabilization of the mRNA 5'-end in Rhodobacter capsulatus

Nucleic Acids Res. 2004 Jan 16;32(1):386-96. doi: 10.1093/nar/gkh174. Print 2004.


The CIRCE element, an inverted DNA repeat, is known to be involved in the temperature-dependent regulation of genes for heat shock proteins in a variety of organisms. The CIRCE element was identified as the target for the HrcA protein, which represses transcription of heat shock genes under normal growth temperature. Our data reveal that the CIRCE element is not involved in the temperature-dependent transcription of the groESL genes in Rhodobacter capsulatus. Apparently, R.capsulatus does not harbour an HrcA protein. The mechanisms of heat shock regulation of the groESL genes in R.capsulatus therefore diverge significantly from the regulatory pathway identified in other organisms. A structural analysis of the CIRCE RNA element revealed a stem of 11 nt pairs and a loop of only 5 nt. This folding differs from a structure with a 9 nt loop suggested previously on the basis of computer analysis. The RNA structure leads to a slight stabilization of the groESL mRNA that is more pronounced at normal growth temperature than under heat shock conditions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 5' Untranslated Regions / chemistry
  • 5' Untranslated Regions / genetics
  • 5' Untranslated Regions / metabolism*
  • Amino Acid Sequence
  • Bacterial Proteins / genetics*
  • Base Sequence
  • Blotting, Southern
  • Chaperonins / genetics*
  • DNA-Binding Proteins
  • Gene Expression Regulation, Bacterial*
  • Genome, Bacterial
  • Genomics
  • Hot Temperature*
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Operon / genetics
  • Promoter Regions, Genetic / genetics
  • RNA Stability*
  • RNA, Bacterial / chemistry
  • RNA, Bacterial / genetics
  • RNA, Bacterial / metabolism
  • Regulatory Sequences, Nucleic Acid / genetics
  • Repressor Proteins / chemistry
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Rhodobacter capsulatus / genetics*
  • Rhodobacter sphaeroides / genetics
  • Sequence Deletion / genetics
  • Transcription, Genetic*


  • 5' Untranslated Regions
  • Bacterial Proteins
  • DNA-Binding Proteins
  • GroESL protein, Bacteria
  • RNA, Bacterial
  • Repressor Proteins
  • Chaperonins