2RM8

The solution structure of phototactic transducer protein HtrII linker region from Natronomonas pharaonis

Summary for 2RM8

• Entry DOI: 10.2210/pdb2rm8/pdb
• Descriptor: Sensory rhodopsin II transducer (1 entity in total)
• Functional Keywords: protein, chemotaxis, chromophore, membrane, methylation, photoreceptor protein, receptor, sensory transduction, transducer, transmembrane, signaling protein
• Biological source: Natronomonas pharaonis
• Cellular location: Cell membrane; Multi-pass membrane protein: P42259
• Total number of polymer chains: 1
• Total formula weight: 7953.51

Authors

Hayashi, K.,Sudo, Y.,Jee, J.,Mishima, M.,Hara, H.,Kamo, N.,Kojima, C. (deposition date: 2007-10-15, release date: 2007-12-04, Last modification date: 2024-05-29)

Primary citation

Hayashi, K.,Sudo, Y.,Jee, J.,Mishima, M.,Hara, H.,Kamo, N.,Kojima, C.
Structural Analysis of the Phototactic Transducer Protein HtrII Linker Region from Natronomonas pharaonis
Biochemistry, 46:14380-14390, 2007

PubMed Abstract: Halobacterial pharaonis phoborhodopsin [ppR, also called Natronomonas pharaonis sensory rhodopsin II (NpSRII)] is a phototaxis protein which transmits a light signal to the cytoplasm through its transducer protein (pHtrII). pHtrII, a two-transmembrane protein that interacts with ppR, belongs to the group of methyl-accepting chemotaxis proteins (MCPs). Several mutation studies have indicated that the linker region connecting the transmembrane and methylation regions is necessary for signal transduction. However, the three-dimensional (3D) structure of an MCP linker region has yet to be reported, and hence, details concerning the signal transduction mechanism remain unknown. Here the structure of the pHtrII linker region was investigated biochemically and biophysically. Following limited proteolysis, only one trypsin resistant fragment in the pHtrII linker region was identified. This fragment forms a homodimer with a Kd value of 115 microM. The 3D structure of this fragment was determined by solution NMR, and only one alpha-helix was found between two HAMP domains of the linker region. This alpha-helix was significantly stabilized within transmembrane protein pHtrII as revealed by CW-EPR. The presence of Af1503 HAMP domain-like structures in the linker region was supported by CD, NMR, and ELDOR data. The alpha-helix determined here presumably works as a mechanical joint between two HAMP domains in the linker region to transfer the photoactivated conformational change downstream.

PubMed: 18001143
DOI: 10.1021/bi701837n

Experimental method

SOLUTION NMR