Flexibility of the Cytoplasmic Domain of the Phototaxis Transducer II from Natronomonas pharaonis. (3rd August 2008)

• Record Type: Journal Article
• Authors: Budyak, Ivan L.; Mironova, Olga S.; Yanamala, Naveena; Manoharan, Vijayalaxmi; Büldt, Georg; Schlesinger, Ramona; Klein-Seetharaman, Judith
• Other Names: Burghardt Thomas P. Academic Editor.
• Is Part Of: Journal of biophysics. Volume 2008(2008)
• Publication Date: 2008-08-03
• Subjects: Biophysics -- Periodicals; Biophysics; Biophysical Phenomena; Biophysics; Periodical; Periodicals; Electronic journals; Fulltext; Internet Resources; Periodicals; 571.4
• DOI: 10.1155/2008/267912
• Languages: English
• ISSNs: 1687-8000

Abstract

Abstract : Chemo- and phototaxis systems in bacteria and archaea serve as models for more complex signal transduction mechanisms in higher eukaryotes. Previous studies of the cytoplasmic fragment of the phototaxis transducer (pHtrII-cyt) from the halophilic archaeon Natronomonas pharaonis showed that it takes the shape of a monomeric or dimeric rod under low or high salt conditions, respectively. CD spectra revealed only approximately 24% helical structure, even in 4 M KCl, leaving it an open question how the rod-like shape is achieved. Here, we conducted CD, FTIR, and NMR spectroscopic studies under different conditions to address this question. We provide evidence that pHtrII-cyt is highly dynamic with strong helical propensity, which allows it to change from monomeric to dimeric helical coiled-coil states without undergoing dramatic shape changes. A statistical analysis of predicted disorder for homologous sequences suggests that structural flexibility is evolutionarily conserved within the methyl-accepting chemotaxis protein family.