Gene Symbol: rhaS
Description: transcriptional activator of rhaBAD and rhaT
Alias: ECK3898, JW3876, rhaC2
Species: Escherichia coli str. K-12 substr. MG1655

Top Publications

  1. Tobin J, Schleif R. Purification and properties of RhaR, the positive regulator of the L-rhamnose operons of Escherichia coli. J Mol Biol. 1990;211:75-89 pubmed
    ..protein that binds to an inverted repeat structure located within the psr promoter, the promoter for the rhaS and rhaR genes...
  2. Egan S, Schleif R. A regulatory cascade in the induction of rhaBAD. J Mol Biol. 1993;234:87-98 pubmed
    The RhaS and RhaR regulatory proteins are encoded in the Escherichia coli L-rhamnose gene cluster...
  3. Holcroft C, Egan S. Roles of cyclic AMP receptor protein and the carboxyl-terminal domain of the alpha subunit in transcription activation of the Escherichia coli rhaBAD operon. J Bacteriol. 2000;182:3529-35 pubmed
    ..Full rhaBAD activation requires the AraC family activator RhaS (bound to a site that overlaps the -35 region of the promoter) and the cyclic AMP receptor protein (CRP; bound ..
  4. Tobin J, Schleif R. Transcription from the rha operon psr promoter. J Mol Biol. 1990;211:1-4 pubmed
    ..In the absence of L-rhamnose, RhaR binds to the psr promoter but does not activate transcription until L-rhamnose is added. ..
  5. Bhende P, Egan S. Genetic evidence that transcription activation by RhaS involves specific amino acid contacts with sigma 70. J Bacteriol. 2000;182:4959-69 pubmed
    b>RhaS activates transcription of the Escherichia coli rhaBAD and rhaT operons in response to L-rhamnose and is a member of the AraC/XylS family of transcription activators...
  6. Giacalone M, Gentile A, Lovitt B, Berkley N, Gunderson C, Surber M. Toxic protein expression in Escherichia coli using a rhamnose-based tightly regulated and tunable promoter system. Biotechniques. 2006;40:355-64 pubmed
    ..Together, these components may enable the stable cloning and functional expression of otherwise toxic proteins. ..
  7. Kolin A, Balasubramaniam V, Skredenske J, Wickstrum J, Egan S. Differences in the mechanism of the allosteric l-rhamnose responses of the AraC/XylS family transcription activators RhaS and RhaR. Mol Microbiol. 2008;68:448-61 pubmed publisher
    Proteins in the largest subset of AraC/XylS family transcription activators, including RhaS and RhaR, have C-terminal domains (CTDs) that mediate DNA-binding and transcription activation, and N-terminal domains (NTDs) that mediate ..
  8. Wickstrum J, Skredenske J, Balasubramaniam V, Jones K, Egan S. The AraC/XylS family activator RhaS negatively autoregulates rhaSR expression by preventing cyclic AMP receptor protein activation. J Bacteriol. 2010;192:225-32 pubmed publisher
    ..The resulting RhaS protein (plus L-rhamnose) activates expression of the L-rhamnose catabolic and transport operons, rhaBAD and rhaT, ..
  9. Tobin J, Schleif R. Positive regulation of the Escherichia coli L-rhamnose operon is mediated by the products of tandemly repeated regulatory genes. J Mol Biol. 1987;196:789-99 pubmed
    ..shows two partially overlapping reading frames, encoding two proteins of molecular weight 32,000 and 35,000 RhaS and RhaR. Both proteins show significant homology to AraC, the positive activator of the arabinose operon...

More Information


  1. Via P, Badia J, Baldoma L, Obradors N, Aguilar J. Transcriptional regulation of the Escherichia coli rhaT gene. Microbiology. 1996;142 ( Pt 7):1833-40 pubmed
    ..constructions grown under different conditions predicted the presence of two putative control elements: one for the RhaS regulatory protein and activating the gene not only by L-rhamnose but also by L-lyxose or L-mannose, the other for ..
  2. Bhende P, Egan S. Amino acid-DNA contacts by RhaS: an AraC family transcription activator. J Bacteriol. 1999;181:5185-92 pubmed
    b>RhaS, an AraC family protein, activates rhaBAD transcription by binding to rhaI, a site consisting of two 17-bp inverted repeat half-sites. In this work, amino acids in RhaS that make base-specific contacts with rhaI were identified...
  3. Wickstrum J, Egan S. Amino acid contacts between sigma 70 domain 4 and the transcription activators RhaS and RhaR. J Bacteriol. 2004;186:6277-85 pubmed
    The RhaS and RhaR proteins are transcription activators that respond to the availability of L-rhamnose and activate transcription of the operons in the Escherichia coli L-rhamnose catabolic regulon...
  4. Wickstrum J, Santangelo T, Egan S. Cyclic AMP receptor protein and RhaR synergistically activate transcription from the L-rhamnose-responsive rhaSR promoter in Escherichia coli. J Bacteriol. 2005;187:6708-18 pubmed
    The Escherichia coli rhaSR operon encodes two AraC family transcription activator proteins, RhaS and RhaR, which regulate expression of the l-rhamnose catabolic regulon in response to l-rhamnose availability...
  5. Kolin A, Jevtic V, Swint Kruse L, Egan S. Linker regions of the RhaS and RhaR proteins. J Bacteriol. 2007;189:269-71 pubmed
    Substitutions within the interdomain linkers of the AraC/XylS family proteins RhaS and RhaR were tested to determine whether side chain identity or linker structure was required for function...
  6. Egan S, Schleif R. DNA-dependent renaturation of an insoluble DNA binding protein. Identification of the RhaS binding site at rhaBAD. J Mol Biol. 1994;243:821-9 pubmed
    Previous work has indicated that the RhaS protein directly activates the L-rhamnose catabolic operon, rhaBAD, and that the likely RhaS binding site lies downstream of position -84 relative to the rhaBAD transcription start point...
  7. Wickstrum J, Skredenske J, Kolin A, Jin D, Fang J, Egan S. Transcription activation by the DNA-binding domain of the AraC family protein RhaS in the absence of its effector-binding domain. J Bacteriol. 2007;189:4984-93 pubmed
    The Escherichia coli L-rhamnose-responsive transcription activators RhaS and RhaR both consist of two domains, a C-terminal DNA-binding domain and an N-terminal dimerization domain...