1M0K

BACTERIORHODOPSIN K INTERMEDIATE AT 1.43 A RESOLUTION


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.43 Å
  • R-Value Free: 0.176 
  • R-Value Work: 0.134 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystallographic structure of the K intermediate of bacteriorhodopsin: conservation of free energy after photoisomerization of the retinal.

Schobert, B.Cupp-Vickery, J.Hornak, V.Smith, S.Lanyi, J.

(2002) J.Mol.Biol. 321: 715-726

  • Primary Citation of Related Structures:  

  • 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 ...

    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.


    Organizational Affiliation

    Department of Physiology and Biophysics, University of California, Irvine, CA 92697, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
bacteriorhodopsin
A
262Halobacterium salinarum (strain ATCC 700922 / JCM 11081 / NRC-1)Mutation(s): 0 
Gene Names: bop
Membrane protein
mpstruct
Group: 
TRANSMEMBRANE PROTEINS: ALPHA-HELICAL
Sub Group: 
Bacterial and Algal Rhodopsins
Protein: 
Bacteriorhodopsin (BR)
Find proteins for P02945 (Halobacterium salinarum (strain ATCC 700922 / JCM 11081 / NRC-1))
Go to UniProtKB:  P02945
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
LI1
Query on LI1

Download SDF File 
Download CCD File 
A
1-[2,6,10.14-TETRAMETHYL-HEXADECAN-16-YL]-2-[2,10,14-TRIMETHYLHEXADECAN-16-YL]GLYCEROL
LIPID FRAGMENT
C42 H86 O3
YERVUJAKCNBGCR-BIHSMRAKSA-N
 Ligand Interaction
RET
Query on RET

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Download CCD File 
A
RETINAL
C20 H28 O
NCYCYZXNIZJOKI-OVSJKPMPSA-N
 Ligand Interaction
SQU
Query on SQU

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Download CCD File 
A
2,10,23-TRIMETHYL-TETRACOSANE
LIPID FRAGMENT
C27 H56
ZADHKSJXSZBQFB-HHHXNRCGSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.43 Å
  • R-Value Free: 0.176 
  • R-Value Work: 0.134 
  • Space Group: P 63
Unit Cell:
Length (Å)Angle (°)
a = 61.179α = 90.00
b = 61.179β = 90.00
c = 111.146γ = 120.00
Software Package:
Software NamePurpose
SHELXL-97refinement
SHELXphasing
SCALEPACKdata scaling
SHELXmodel building
DENZOdata reduction

Structure Validation

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Entry History 

Deposition Data

  • Deposited Date: 2002-06-13 
  • Released Date: 2002-09-11 
  • Deposition Author(s): Lanyi, J.K.

Revision History 

  • Version 1.0: 2002-09-11
    Type: Initial release
  • Version 1.1: 2008-04-28
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Derived calculations, Version format compliance