1M0K

BACTERIORHODOPSIN K INTERMEDIATE AT 1.43 A RESOLUTION

1M0K の概要

• エントリーDOI: 10.2210/pdb1m0k/pdb
• 関連するPDBエントリー: 1M0L 1M0M
• 分子名称: bacteriorhodopsin, RETINAL, 1-[2,6,10.14-TETRAMETHYL-HEXADECAN-16-YL]-2-[2,10,14-TRIMETHYLHEXADECAN-16-YL]GLYCEROL, ... (5 entities in total)
• 機能のキーワード: ion pump, membrane protein, retinal protein, lipids, photoreceptor, haloarchaea, 7-transmembrane, serpentine, merohedral twinning, ion transport
• 由来する生物種: Halobacterium salinarum
• 細胞内の位置: Cell membrane; Multi-pass membrane protein: P02945
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 37243.94

構造登録者

Lanyi, J.K. (登録日: 2002-06-13, 公開日: 2002-09-11, 最終更新日: 2024-11-13)

主引用文献

Schobert, B.,Cupp-Vickery, J.,Hornak, V.,Smith, S.,Lanyi, J.
Crystallographic structure of the K intermediate of bacteriorhodopsin: conservation of free energy after photoisomerization of the retinal.
J.Mol.Biol., 321:715-726, 2002

PubMed Abstract: The K state, an early intermediate of the bacteriorhodopsin photocycle, contains the excess free energy used for light-driven proton transport. The energy gain must reside in or near the photoisomerized retinal, but in what form has long been an open question. We produced the K intermediate in bacteriorhodopsin crystals in a photostationary state at 100K, with 40% yield, and determined its X-ray diffraction structure to 1.43 A resolution. In independent refinements of data from four crystals, the changes are confined mainly to the photoisomerized retinal. The retinal is 13-cis,15-anti, as known from vibrational spectroscopy. The C13=C14 bond is rotated nearly fully to cis from the initial trans configuration, but the C14-C15 and C15=NZ bonds are partially counter-rotated. This strained geometry keeps the direction of the Schiff base N-H bond vector roughly in the extracellular direction, but the angle of its hydrogen bond with water 402, that connects it to the anionic Asp85 and Asp212, is not optimal. Weakening of this hydrogen bond may account for many of the reported features of the infrared spectrum of K, and for its photoelectric signal, as well as the deprotonation of the Schiff base later in the cycle. Importantly, although 13-cis, the retinal does not assume the expected bent shape of this configuration. Comparison of the calculated energy of the increased angle of C12-C13=C14, that allows this distortion, with the earlier reported calorimetric measurement of the enthalpy gain of the K state indicates that a significant part of the excess energy is conserved in the bond strain at C13.

PubMed: 12206785
DOI: 10.1016/S0022-2836(02)00681-2

実験手法

X-RAY DIFFRACTION (1.43 Å)