scholarly journals Structures of the archaerhodopsin-3 transporter reveal that disordering of internal water networks underpins receptor sensitization

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Juan F. Bada Juarez ◽  
Peter J. Judge ◽  
Suliman Adam ◽  
Danny Axford ◽  
Javier Vinals ◽  
...  

AbstractMany transmembrane receptors have a desensitized state, in which they are unable to respond to external stimuli. The family of microbial rhodopsin proteins includes one such group of receptors, whose inactive or dark-adapted (DA) state is established in the prolonged absence of light. Here, we present high-resolution crystal structures of the ground (light-adapted) and DA states of Archaerhodopsin-3 (AR3), solved to 1.1 Å and 1.3 Å resolution respectively. We observe significant differences between the two states in the dynamics of water molecules that are coupled via H-bonds to the retinal Schiff Base. Supporting QM/MM calculations reveal how the DA state permits a thermodynamic equilibrium between retinal isomers to be established, and how this same change is prevented in the ground state in the absence of light. We suggest that the different arrangement of internal water networks in AR3 is responsible for the faster photocycle kinetics compared to homologs.

2010 ◽  
Vol 98 (3) ◽  
pp. 287a
Author(s):  
Mikkel Jensen ◽  
Erica C. Saint Clair ◽  
Alan Gabel ◽  
Vladislav B. Bergo ◽  
Elena N. Spudich ◽  
...  

2009 ◽  
Vol 96 (3) ◽  
pp. 680a
Author(s):  
Eduardo Jardón-Valadez ◽  
Ana-Nicoleta Bondar ◽  
Douglas J. Tobias

2002 ◽  
Vol 19 (4) ◽  
pp. 257-265 ◽  
Author(s):  
Yuji Furutani ◽  
Hideki Kandori

Biochemistry ◽  
2001 ◽  
Vol 40 (51) ◽  
pp. 15693-15698 ◽  
Author(s):  
Hideki Kandori ◽  
Yuji Furutani ◽  
Kazumi Shimono ◽  
Yoshinori Shichida ◽  
Naoki Kamo

2005 ◽  
Vol 94 (22) ◽  
Author(s):  
A. Svendsen ◽  
H. Bluhme ◽  
M. O. A. El Ghazaly ◽  
K. Seiersen ◽  
S. Brøndsted Nielsen ◽  
...  

1982 ◽  
Vol 37 (6) ◽  
pp. 559-563
Author(s):  
K.-H. Gericke ◽  
F. J. Comes

Abstract Rotational relaxation of OH molecules in the 2II electronic ground state has been observed to occur in collisions with water molecules with gas kinetic probability. It causes an additional contribution to the already well known sources of interference when LIF is used to monitor tropospheric OH. As the laser generated OH is originally produced mostly in high rotational states, the fast relaxation phenomenon leads to a further population of OH in low rotational states. These states are used to monitor tropospheric OH by spectroscopic methods. The observed effect therefore increases the interference. A mathematical analysis is presented, revealing the effect of all relevant parameters.


2012 ◽  
Vol 68 (5) ◽  
pp. o209-o212 ◽  
Author(s):  
Barbara Wicher ◽  
Krystian Pyta ◽  
Piotr Przybylski ◽  
Ewa Tykarska ◽  
Maria Gdaniec

Rifampicin belongs to the family of naphthalenic ansamycin antibiotics. The first crystal structure of rifampicin in the form of the pentahydrate was reported in 1975 [Gadret, Goursolle, Leger & Colleter (1975).Acta Cryst.B31, 1454–1462] with the rifampicin molecule assumed to be neutral. Redetermination of this crystal structure now shows that one of the phenol –OH groups is deprotonated, with the proton transferred to a piperazine N atom, confirming earlier spectroscopic results that indicated a zwitterionic form for the molecule, namely (2S,12Z,14E,16S,17S,18R,19R,20R,21S,22R,23S,24E)-21-acetyloxy-6,9,17,19-tetrahydroxy-23-methoxy-2,4,12,16,18,20,22-heptamethyl-8-[(E)-N-(4-methylpiperazin-4-ium-1-yl)formimidoyl]-1,11-dioxo-1,2-dihydro-2,7-(epoxypentadeca[1,11,13]trienimino)naphtho[2,1-b]furan-5-olate pentahydrate, C43H58N4O12·5H2O. The molecular structure of this antibiotic is stabilized by a system of four intramolecular O—H...O and N—H...N hydrogen bonds. Four of the symmetry-independent water molecules are arrangedviahydrogen bonds into helical chains extending along [100], whereas the fifth water molecule forms only one hydrogen bond, to the amide group O atom. The rifampicin molecules interactviaO—H...O hydrogen bonds, generating chains along [001]. Rifampicin pentahydrate is isostructural with recently reported rifampicin trihydrate methanol disolvate.


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