scholarly journals Slow conformational changes of blue light sensor BLUF proteins in milliseconds

2021 ◽  
Author(s):  
Shunrou Tokonami ◽  
Morihiko Onose ◽  
Yusuke Nakasone ◽  
Masahide Terazima
Keyword(s):  
Blue Light ◽  
Conformational Changes ◽  
Visible Region ◽  
Reaction Scheme ◽  
Terminal Region ◽  
Red Shift ◽  
Functional Region ◽  
Light Sensor ◽  
Bluf Domain ◽  
Flavin Binding

BLUF (blue light sensor using flavin) proteins consist of flavin-binding BLUF domains and functional domains. Upon blue light excitation, the hydrogen bond network around the flavin chromophore changes, and the absorption spectrum in the visible region exhibits red-shift. Ultimately, the light information received in the BLUF domain is transmitted to the functional region. It has been believed that this red-shift is complete within nanoseconds. Contrary to this commonly accepted scheme, in this study, slow reaction kinetics were discovered in milliseconds (τ1- and τ2-phase) for all the BLUF proteins examined (AppA, OaPAC, BlrP1, YcgF, PapB, SyPixD, and TePixD). Despite extensive reports on BLUF, this is the first clear observation of the BLUF protein absorption change with the duration in the millisecond time region. From the measurements of some domain-deleted mutants of OaPAC and two chimeric mutants of PixD proteins, it was found that the slower dynamics (τ2-phase) are strongly affected by the size and nature of the C-terminal region adjacent to the BLUF domain. Hence, this millisecond reaction is a significant indicator of conformational changes in the C-terminal region, which is essential for the biological functions. On the other hand, the τ1-phase commonly exists in all BLUF proteins, including any mutants. The origin of the slow dynamics was studied using site-specific mutants. These results clearly show the importance of Trp in the BLUF domain. Based on this, a reaction scheme for the BLUF reaction is proposed.

FTIR Study on the Hydrogen Bond Structure of a Key Tyrosine Residue in the Flavin-Binding Blue Light Sensor TePixD fromThermosynechococcus elongatus†

Biochemistry ◽  
2007 ◽  
Vol 46 (22) ◽  
pp. 6459-6467 ◽  
Author(s):  
Ryouta Takahashi ◽  
Koji Okajima ◽  
Hiroyuki Suzuki ◽  
Hiro Nakamura ◽  
Masahiko Ikeuchi ◽  
...  
Keyword(s):  
Hydrogen Bond ◽  
Blue Light ◽  
Tyrosine Residue ◽  
Ftir Study ◽  
Light Sensor ◽  
Flavin Binding

scholarly journals Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4230
Author(s):  
Andreas Windischbacher ◽  
Luca Steiner ◽  
Ritesh Haldar ◽  
Christof Wöll ◽  
Egbert Zojer ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Photophysical Properties ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Red Shift ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Exciton Coupling ◽  
Metal Organic ◽  
Crystalline Metal

In recent years, the photophysical properties of crystalline metal-organic frameworks (MOFs) have become increasingly relevant for their potential application in light-emitting devices, photovoltaics, nonlinear optics and sensing. The availability of high-quality experimental data for such systems makes them ideally suited for a validation of quantum mechanical simulations, aiming at an in-depth atomistic understanding of photophysical phenomena. Here we present a computational DFT study of the absorption and emission characteristics of a Zn-based surface-anchored metal-organic framework (Zn-SURMOF-2) containing anthracenedibenzoic acid (ADB) as linker. Combining band-structure and cluster-based simulations on ADB chromophores in various conformations and aggregation states, we are able to provide a detailed explanation of the experimentally observed photophysical properties of Zn-ADB SURMOF-2: The unexpected (weak) red-shift of the absorption maxima upon incorporating ADB chromophores into SURMOF-2 can be explained by a combination of excitonic coupling effects with conformational changes of the chromophores already in their ground state. As far as the unusually large red-shift of the emission of Zn-ADB SURMOF-2 is concerned, based on our simulations, we attribute it to a modification of the exciton coupling compared to conventional H-aggregates, which results from a relative slip of the centers of neighboring chromophores upon incorporation in Zn-ADB SURMOF-2.

scholarly journals Conformational changes in an epitope localized to the NH2-terminal region of protein C

1989 ◽  
Vol 264 (31) ◽  
pp. 18781-18788 ◽  
Author(s):  
C L Orthner ◽  
R D Madurawe ◽  
W H Velander ◽  
W N Drohan ◽  
F D Battey ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Protein C ◽  
Terminal Region

scholarly journals Insights into histidine kinase activation mechanisms from the monomeric blue light sensor EL346

2019 ◽  
Vol 116 (11) ◽  
pp. 4963-4972 ◽  
Author(s):  
Igor Dikiy ◽  
Uthama R. Edupuganti ◽  
Rinat R. Abzalimov ◽  
Peter P. Borbat ◽  
Madhur Srivastava ◽  
...  
Keyword(s):  
Blue Light ◽  
Conformational Changes ◽  
Histidine Kinase ◽  
Structural Changes ◽  
Molecular Mechanisms ◽  
Catalytic Domain ◽  
Response Regulator ◽  
Phosphoryl Group ◽  
Dark State ◽  
Light Sensing

Translation of environmental cues into cellular behavior is a necessary process in all forms of life. In bacteria, this process frequently involves two-component systems in which a sensor histidine kinase (HK) autophosphorylates in response to a stimulus before subsequently transferring the phosphoryl group to a response regulator that controls downstream effectors. Many details of the molecular mechanisms of HK activation are still unclear due to complications associated with the multiple signaling states of these large, multidomain proteins. To address these challenges, we combined complementary solution biophysical approaches to examine the conformational changes upon activation of a minimal, blue-light–sensing histidine kinase from Erythrobacter litoralis HTCC2594, EL346. Our data show that multiple conformations coexist in the dark state of EL346 in solution, which may explain the enzyme’s residual dark-state activity. We also observe that activation involves destabilization of the helices in the dimerization and histidine phosphotransfer-like domain, where the phosphoacceptor histidine resides, and their interactions with the catalytic domain. Similar light-induced changes occur to some extent even in constitutively active or inactive mutants, showing that light sensing can be decoupled from activation of kinase activity. These structural changes mirror those inferred by comparing X-ray crystal structures of inactive and active HK fragments, suggesting that they are at the core of conformational changes leading to HK activation. More broadly, our findings uncover surprising complexity in this simple system and allow us to outline a mechanism of the multiple steps of HK activation.

Time-Resolved Study of Interprotein Signaling Process of a Blue Light Sensor PapB–PapA Complex

2019 ◽  
Vol 123 (15) ◽  
pp. 3210-3218 ◽  
Author(s):  
Yusuke Nakasone ◽  
Koutaro Kikukawa ◽  
Shinji Masuda ◽  
Masahide Terazima
Keyword(s):  
Blue Light ◽  
Time Resolved ◽  
Light Sensor ◽  
Signaling Process
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