Bacteriophage Mu C protein is a new member of unusual leucine zipper-HTH class of proteins

Atanu Chakraborty, Bindu Diana Paul, Valakunja Nagaraja

Research output: Contribution to journalArticle


Transcription activator protein C of bacteriophage Mu activates transcription of the late genes, including mom, during the lytic cycle of the phage. C binding to its site leads to the alteration in DNA topology of the promoter elements resulting in RNA polymerase (RNAP) recruitment. At the next step, the transactivator enhances promoter clearance of RNAP from P mom. The C protein binds DNA with a very high affinity using a carboxyl-terminal helix turn helix (HTH) motif which has similarity with the HTH from paired domain of Drosophila prd protein. Previous studies established that the protein is dimeric in free and DNA bound forms. We describe now the unique dimerization interface of the protein. Two heptad repeats of hydrophobic amino acids found in the protein were considered to be the candidates for dimerization region. Site-directed mutational analysis revealed that the amino-terminal coiled coil region is not the dimerization determinant. In contrast, similar mutagenesis studies indicated a role for the leucine zipper motif, located in the middle region of the protein, in dimerization. Mixed oligomerization assays confirmed the importance of leucine zipper in C dimer formation establishing the presence of an uncommon zipper-HTH domain in the transactivator.

Original languageEnglish (US)
Pages (from-to)1-5
Number of pages5
JournalProtein Engineering, Design and Selection
Issue number1
StatePublished - Jan 1 2007
Externally publishedYes



  • C protein
  • Helix turn helix
  • Leucine zipper
  • Phage Mu
  • Transcription activation

ASJC Scopus subject areas

  • Biotechnology
  • Bioengineering
  • Biochemistry
  • Molecular Biology

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