Pathways of proton release in the bacteriorhodopsin photocycle

Biochemistry ◽  
1992 ◽  
Vol 31 (36) ◽  
pp. 8535-8543 ◽  
Author(s):  
Laszlo Zimanyi ◽  
Gyorgy Varo ◽  
Man Chang ◽  
Baofu Ni ◽  
Richard Needleman ◽  
...  
Keyword(s):  
Proton Release ◽  
Bacteriorhodopsin Photocycle

Effect of salt on the tyrosine and protonated Schiff base deprotonation kinetics in bacteriorhodopsin

1985 ◽  
Vol 63 (7) ◽  
pp. 1699-1704 ◽  
Author(s):  
Paul Dupuis ◽  
M. A. El-Sayed
Keyword(s):  
Schiff Base ◽  
Quantum Yield ◽  
Salt Concentration ◽  
Slow Component ◽  
High Salt ◽  
Proton Release ◽  
High Ph ◽  
Bacteriorhodopsin Photocycle

It is observed that the number of protons pumped per M412 formed in the bacteriorhodopsin photocycle almost doubles at high salt concentrations. In this paper, we studied the rates of deprotonation of tyrosine and of the two components of the protonated Schiff base at high salt concentrations, and at different pHs and temperatures. It is found that at pH = 7, increasing the salt concentration decreases the rates of deprotonation of the protonated Schiff base and tyrosine. This strongly suggests that the observed gain in the quantum yield of proton release per M412 formed when the salt concentration is increased is not a result of an increase in these rates. However, at high pH, e.g. 9.6, increasing the salt concentration increases the rate of deprotonation of the Schiff base by about 50%. Under all conditions, the slow component of the Schiff base is found to lose its proton prior to tyrosine.

scholarly journals Relationship of proton release at the extracellular surface to deprotonation of the schiff base in the bacteriorhodopsin photocycle

1995 ◽  
Vol 68 (4) ◽  
pp. 1518-1530 ◽  
Author(s):  
Y. Cao ◽  
L.S. Brown ◽  
J. Sasaki ◽  
A. Maeda ◽  
R. Needleman ◽  
...  
Keyword(s):  
Schiff Base ◽  
Proton Release ◽  
Relationship Of ◽  
Bacteriorhodopsin Photocycle

Role of Arginine-82 in Fast Proton Release during the Bacteriorhodopsin Photocycle:  A Time-Resolved FT-IR Study of Purple Membranes Containing15N-Labeled Arginine†

Biochemistry ◽  
2004 ◽  
Vol 43 (40) ◽  
pp. 12809-12818 ◽  
Author(s):  
Yaowu Xiao ◽  
M. Shane Hutson ◽  
Marina Belenky ◽  
Judith Herzfeld ◽  
Mark S. Braiman
Keyword(s):  
Fast Proton ◽  
Proton Release ◽  
Time Resolved ◽  
Ft Ir ◽  
Ir Study ◽  
Bacteriorhodopsin Photocycle ◽  
Purple Membranes

scholarly journals Structure Changes upon Deprotonation of the Proton Release Group in the Bacteriorhodopsin Photocycle

2012 ◽  
Vol 103 (3) ◽  
pp. 444-452 ◽  
Author(s):  
Joel E. Morgan ◽  
Ahmet S. Vakkasoglu ◽  
Janos K. Lanyi ◽  
Johan Lugtenburg ◽  
Robert B. Gennis ◽  
...  
Keyword(s):  
Proton Release ◽  
Structure Changes ◽  
Release Group ◽  
Bacteriorhodopsin Photocycle

Evidence for the Rate of the Final Step in the Bacteriorhodopsin Photocycle Being Controlled by the Proton Release Group:  R134H Mutant†

Biochemistry ◽  
2000 ◽  
Vol 39 (9) ◽  
pp. 2325-2331 ◽  
Author(s):  
Miao Lu ◽  
Sergei P. Balashov ◽  
Thomas G. Ebrey ◽  
Ning Chen ◽  
Yumei Chen ◽  
...  
Keyword(s):  
Proton Release ◽  
Release Group ◽  
Bacteriorhodopsin Photocycle

Constant pH Molecular Dynamics Reveals How Proton Release Drives the Conformational Transition of a Transmembrane Efflux Pump

2017 ◽  
Author(s):  
Jana Shen ◽  
Zhi Yue ◽  
Helen Zgurskaya ◽  
Wei Chen
Keyword(s):  
Molecular Dynamics ◽  
Conformational Changes ◽  
Transmembrane Domain ◽  
Conformational Transition ◽  
Conformational Dynamics ◽  
Proton Release ◽  
Intrinsic Resistance ◽  
Constant Ph ◽  
Wide Range ◽  
Constant Ph Molecular Dynamics

AcrB is the inner-membrane transporter of E. coli AcrAB-TolC tripartite efflux complex, which plays a major role in the intrinsic resistance to clinically important antibiotics. AcrB pumps a wide range of toxic substrates by utilizing the proton gradient between periplasm and cytoplasm. Crystal structures of AcrB revealed three distinct conformational states of the transport cycle, substrate access, binding and extrusion, or loose (L), tight (T) and open (O) states. However, the specific residue(s) responsible for proton binding/release and the mechanism of proton-coupled conformational cycling remain controversial. Here we use the newly developed membrane hybrid-solvent continuous constant pH molecular dynamics technique to explore the protonation states and conformational dynamics of the transmembrane domain of AcrB. Simulations show that both Asp407 and Asp408 are deprotonated in the L/T states, while only Asp408 is protonated in the O state. Remarkably, release of a proton from Asp408 in the O state results in large conformational changes, such as the lateral and vertical movement of transmembrane helices as well as the salt-bridge formation between Asp408 and Lys940 and other sidechain rearrangements among essential residues.Consistent with the crystallographic differences between the O and L protomers, simulations offer dynamic details of how proton release drives the O-to-L transition in AcrB and address the controversy regarding the proton/drug stoichiometry. This work offers a significant step towards characterizing the complete cycle of proton-coupled drug transport in AcrB and further validates the membrane hybrid-solvent CpHMD technique for studies of proton-coupled transmembrane proteins which are currently poorly understood. <p><br></p>

scholarly journals Active site lysine backbone undergoes conformational changes in the bacteriorhodopsin photocycle.

1994 ◽  
Vol 269 (10) ◽  
pp. 7387-7389
Author(s):  
H. Takei ◽  
Y. Gat ◽  
Z. Rothman ◽  
A. Lewis ◽  
M. Sheves
Keyword(s):  
Conformational Changes ◽  
Active Site ◽  
Bacteriorhodopsin Photocycle
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