2I20

Bacteriorhodopsin/lipid complex, M state of D96A mutant

Summary for 2I20

• Entry DOI: 10.2210/pdb2i20/pdb
• Related: 1C8S
• Descriptor: Bacteriorhodopsin, RETINAL, 1-[2,6,10.14-TETRAMETHYL-HEXADECAN-16-YL]-2-[2,10,14-TRIMETHYLHEXADECAN-16-YL]GLYCEROL, ... (5 entities in total)
• Functional Keywords: ion pump, membrane protein, retinal protein, lipids, photoreceptor, haloarchaea, 7-transmembrane, serpentine, ion transport, transport protein
• Biological source: Halobacterium salinarum
• Cellular location: Cell membrane; Multi-pass membrane protein: P02945
• Total number of polymer chains: 1
• Total formula weight: 35859.35

Authors

Lanyi, J.K.,Schobert, B. (deposition date: 2006-08-15, release date: 2006-10-10, Last modification date: 2024-10-30)

Primary citation

Lanyi, J.K.,Schobert, B.
Propagating Structural Perturbation Inside Bacteriorhodopsin: Crystal Structures of the M State and the D96A and T46V Mutants.
Biochemistry, 45:12003-12010, 2006

PubMed Abstract: The X-ray diffraction structure of the non-illuminated D96A bacteriorhodopsin mutant reveals structural changes as far away as 15 A from residue 96, at the retinal, Trp-182, Ala-215, and waters 501, 402, and 401. The Asp-to-Ala side-chain replacement breaks its hydrogen bond with Thr-46, and the resulting separation of the cytoplasmic ends of helices B and C is communicated to the retinal region through a chain of covalent and hydrogen bonds. The unexpected long-range consequences of the D96A mutation include breaking the hydrogen bond between O of Ala-215 and water 501 and the formation of a new hydrogen bond between water molecules 401 and 402 in the extracellular region. Because in the T46V mutant a new water molecule appears at Asp-96 and its hydrogen-bond to Ile-45 replaces Thr-46 as its link to helix B, the separation of helices B and C is smaller than that in D96A, and there are no atomic displacements elsewhere in the protein. Propagation of conformational changes along the chain between the retinal and Thr-46 had been observed earlier in the crystal structures of the D96N and E204Q mutants but in the trapped M state. Consistent with the perturbation of the retinal region in D96A, little change of the Thr-46 region occurs between the non-illuminated and M states of this mutant. It appears that a local perturbation can propagate along a track in both directions between the retinal and the Asp-96/Thr-46 pair, either from photoisomerization of the retinal in the wild-type protein in one case or from the D96A mutation in the other.

PubMed: 17002299
DOI: 10.1021/bi061310i

Experimental method

X-RAY DIFFRACTION (2.08 Å)