title: pH-dependent structural change of the extracellular sensor domain of the DraK histidine kinase from Streptomyces coelicolor.
abstract: Recently, the DraR/DraK (Sco3063/Sco3062) two-component system (TCS) of Streptomycescoelicolor has been reported to be involved in the differential regulation of antibiotic biosynthesis. However, it has not been shown that under which conditions and how the DraR/DraK TCS is activated to initiate the signal transduction process. Therefore, to understand the sensing mechanism, structural study of the sensory domain of DraK is highly required. Here, we report the biochemical and biophysical properties of the extracellular sensory domain (ESD) of DraK. We observed a reversible pH-dependent conformational change of the ESD in a pH range of 2.5-10. Size-exclusion chromatography and AUC (analytical ultracentrifugation) data indicated that the ESD is predominantly monomeric in solution and exists in equilibrium between monomer and dimer states in acidic condition. Using NMR (nuclear magnetic resonance) and CD (circular dichroism) spectroscopy, our findings suggest that the structure of the ESD at low pH is more structured than that at high pH. In particular, the glutamate at position 83 is an important residue for the pH-dependent conformational change. These results suggest that this pH-dependent conformational change of ESD may be involved in signal transduction process of DraR/DraK TCS.
authors: Division of Magnetic Resonance, Korea Basic Science Institute (KBSI), 16 Yeongudanji-Ro, Ochang, Chungbuk 363-883, Republic of Korea.
authors: Kwon Joo
authors: KJ
authors: Yeo
authors: Eun Hye
authors: EH
authors: Kim
authors: Eunha
authors: E
authors: Hwang
authors: Young-Hyun
authors: YH
authors: Han
authors: Yumi
authors: Y
authors: Eo
authors: Hyun Jung
authors: HJ
authors: Kim
authors: Ohsuk
authors: O
authors: Kwon
authors: Young-Soo
authors: YS
authors: Hong
authors: Chaejoon
authors: C
authors: Cheong
authors: Hae-Kap
authors: HK
authors: Cheong
mesh_terms: D002850:Chromatography, Gel; D003593:Cytoplasm / Q000201:enzymology; D018698:Glutamic Acid / Q000737:chemistry / Q000235:genetics; D000071677:Histidine Kinase; D006863:Hydrogen-Ion Concentration; D011494:Protein Kinases / Q000737:chemistry* / Q000235:genetics; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D048372:Streptomyces coelicolor / Q000201:enzymology*
chemical_list: D018698:Glutamic Acid; D011494:Protein Kinases; D000071677:Histidine Kinase