Shape and oligomerization state of the cytoplasmic domain of the phototaxis transducer II from Natronobacterium pharaonis

Budyak, I. L.; Mironova, O. S.; Schlesinger, R.; Klein-Seetharaman, J.; Zaccai, G.; Pipich, V.

doi:10.1073/pnas.0607201103

Journal Article

Shape and oligomerization state of the cytoplasmic domain of the phototaxis transducer II from Natronobacterium pharaonis

Budyak, I. L. ; Pipich, V.FZJ* ; Mironova, O. S. ; Schlesinger, R. ; Zaccai, G. ; Klein-Seetharaman, J.

2006
Academy Washington, DC

Proceedings of the National Academy of Sciences of the United States of America 103, 15428 - 15433 (2006) [10.1073/pnas.0607201103]

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Please use a persistent id in citations: http://hdl.handle.net/2128/2656 doi:10.1073/pnas.0607201103

Abstract: Phototaxis allows archaea to adjust flagellar motion in response to light. In the photophobic response of Natronobacterium pharaonis, light-activated sensory rhodopsin II causes conformational changes in the transducer II protein (pHtrII), initiating the two-component signaling system analogous to bacterial chemotaxis. pHtrII's cytoplasmic domain (pHtrII-cyt) is homologous to the cytoplasmic domains of eubacterial chemotaxis receptors. Chemotaxis receptors require dimerization for activity and are in vivo-organized in large clusters. In this study we investigated the oligomerization and aggregation states of pHtrII-cyt by using chemical cross-linking, analytical gel-filtration chromatography, and small-angle neutron scattering. We show that pHtrII-cyt is monomeric in dilute buffers, but forms dimers in 4 M KCl, the physiological salt concentration for halophilic archaea. At high ammonium sulfate concentration, the protein forms higher-order aggregates. The monomeric protein has a rod-like shape, 202 A in length and 14.4 A in diameter; upon dimerization the length increases to 248 A and the diameter to 18.2 A. These results suggest that under high salt concentration the shape and oligomerization state of pHtrII-cyt are comparable to those of chemotaxis receptors.

Keyword(s): Archaeal Proteins: chemistry (MeSH) ; Archaeal Proteins: genetics (MeSH) ; Archaeal Proteins: metabolism (MeSH) ; Biopolymers: chemistry (MeSH) ; Carotenoids: chemistry (MeSH) ; Carotenoids: genetics (MeSH) ; Carotenoids: metabolism (MeSH) ; Cross-Linking Reagents: chemistry (MeSH) ; Crystallography, X-Ray (MeSH) ; Dimerization (MeSH) ; Light (MeSH) ; Natronobacterium: chemistry (MeSH) ; Natronobacterium: metabolism (MeSH) ; Particle Size (MeSH) ; Phototrophic Processes: physiology (MeSH) ; Protein Structure, Quaternary (MeSH) ; Protein Structure, Tertiary (MeSH) ; Archaeal Proteins ; Biopolymers ; Cross-Linking Reagents ; phototaxis receptor sensory rhodopsin II, Natronobacterium pharaonis ; Carotenoids ; J ; archaebacteria (auto) ; dynamics (auto) ; halophilic (auto) ; small-angle neutron scattering (auto)