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Journal of Bacteriology, February 2008, p. 1317-1328, Vol. 190, No. 4
0021-9193/08/$08.00+0     doi:10.1128/JB.01074-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.

PhoP-PhoP Interaction at Adjacent PhoP Binding Sites Is Influenced by Protein Phosphorylation{triangledown} ,{ddagger}

Akesh Sinha,{dagger} Sankalp Gupta,{dagger} Shweta Bhutani, Anuj Pathak, and Dibyendu Sarkar*

Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India

Received 7 July 2007/ Accepted 26 November 2007

Mycobacterium tuberculosis PhoP regulates the expression of unknown virulence determinants and the biosynthesis of complex lipids. PhoP, like other members of the OmpR family, comprises a phosphorylation domain at the amino-terminal half and a DNA-binding domain at the carboxy-terminal half of the protein. To explore structural effect of protein phosphorylation and to examine effect of phosphorylation on DNA binding, purified PhoP was phosphorylated by acetyl phosphate in a reaction that was dependent on Mg2+ and Asp-71. Protein phosphorylation was not required for DNA binding; however, phosphorylation enhanced in vitro DNA binding through protein-protein interaction(s). Evidence is presented here that the protein-protein interface is different in the unphosphorylated and phosphorylated forms of PhoP and that specific DNA binding plays a critical role in changing the nature of the protein-protein interface. We show that phosphorylation switches the transactivation domain to a different conformation, which specifies additional protein-protein contacts between PhoP protomers bound to adjacent cognate sites. Together, our observations raise the possibility that PhoP, in the unphosphorylated and phosphorylated forms, may be capable of adopting different orientations as it binds to a vast array of genes to activate or repress transcription.

* Corresponding author. Mailing address: Institute of Microbial Technology, Sector 39A, Chandigarh 160036, India. Phone: 091 172 269 5215, ext. 3223. Fax: 091 172 269 0585. E-mail: dibyendu{at}imtech.res.in

{triangledown} Published ahead of print on 7 December 2007.

{ddagger} Supplemental material for this article may be found at http://jb.asm.org/.

{dagger} A.S. and S.G. contributed equally to this study.

Journal of Bacteriology, February 2008, p. 1317-1328, Vol. 190, No. 4
0021-9193/08/$08.00+0     doi:10.1128/JB.01074-07
Copyright © 2008, American Society for Microbiology. All Rights Reserved.



This article has been cited by other articles:

  • Gonzalo-Asensio, J., Soto, C. Y., Arbues, A., Sancho, J., del Carmen Menendez, M., Garcia, M. J., Gicquel, B., Martin, C. (2008). The Mycobacterium tuberculosis phoPR Operon Is Positively Autoregulated in the Virulent Strain H37Rv. J. Bacteriol. 190: 7068-7078 [Abstract] [Full Text]  


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