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

Chakraborty, Atanu and Paul, Bindu Diana and Nagaraja, Valakunja (2007) Bacteriophage Mu C protein is a new member of unusual leucine zipper-HTH class of proteins. In: Protein Engineering Design and Selection, 20 (1). pp. 1-5.

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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.

Item Type: Journal Article
Publication: Protein Engineering Design and Selection
Publisher: Oxford University Press
Additional Information: Copyright of this article belongs to the Oxford University Press.
Keywords: C protein/helix;Turn helix/leucine;Zipper/phage;Mu/transcription activation
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 10 Apr 2007
Last Modified: 19 Sep 2010 04:36
URI: http://eprints.iisc.ac.in/id/eprint/10529

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