Dual role for transactivator protein C in activation of mom promoter of bacteriophage Mu

Chakraborty, Atanu ; Nagaraja, Valakunja (2006) Dual role for transactivator protein C in activation of mom promoter of bacteriophage Mu Journal of Biological Chemistry, 281 (13). pp. 8511-8517. ISSN 0021-9258

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Official URL: http://www.jbc.org/content/281/13/8511.full

Related URL: http://dx.doi.org/10.1074/jbc.M512906200

Abstract

Transactivator C protein of bacteriophage Mu activates the mom gene of the phage by an unusual mechanism. DNA binding by C to its site results in unwinding of the neighboring sequences, realigning the out-of-phase promoter elements to facilitate RNA polymerase (RNAP) binding. High level stimulation of a C-independent constitutive promoter mutant (where RNAP is already bound) by the transactivator suggested an additional mechanism of transcription activation at a step after RNAP recruitment. In this study, we have investigated the various steps of promoter-polymerase interactions during transcription initiation by using both the promoter mutant and a positive control (pc) mutant of C protein. The transactivator does not influence formation of the open complex or its stability after facilitating the RNAP binding. However, at a subsequent step, the protein exerts an important role, enhancing the promoter clearance by increasing the productive RNAP.promoter complex. The pc mutant of the transactivator C is compromised at this step, supporting the additional downstream role for C in mom transcription activation. We suggest that this unusual multistep activation of Pmom has evolved to ensure irreversibility of the switch during the late lytic cycle of the phage.

Item Type:Article
Source:Copyright of this article belongs to American Society for Biochemistry and Molecular Biology.
ID Code:26947
Deposited On:08 Dec 2010 12:57
Last Modified:17 May 2016 10:14

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