Strong Donation of the Hydrogen Bond of Tyrosine during Photoactivation of the BLUF Domain

Iwata, Tatsuya; Watanabe, Akihide; Iseki, Mineo; Watanabe, Masakatsu; Kandori, Hideki

doi:10.1021/jz2003974

Cited by 50 publications

(75 citation statements)

References 34 publications

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“…The X-ray datasets of OaPAC (dark-state PDB 4YUS, and this work PDB 5X4T) allow the atomic temperature factors to be refined and imply that the Oe1 atom of Gln-48 receives a hydrogen bond from the Tyr-6 hydroxyl group throughout the photocycle. This inference matches the conclusion from FTIR studies of TePixD (29) and AppA (30), which show that a hydrogen bond donated by the tyrosine to the glutamine oxygen becomes stronger on photoactivation. The oxygen-oxygen distance in the OaPAC X-ray models falls from 2.82 Å in the dark state to 2.69 Å after illumination, but the difference is barely significant, given the atomic positional error.…”

Section: Discussionsupporting

confidence: 89%

Molecular mechanism of photoactivation of a light-regulated adenylate cyclase

Ohki

Sato‐Tomita

Matsunaga

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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The photoactivated adenylate cyclase (PAC) from the photosynthetic cyanobacterium Oscillatoria acuminata (OaPAC) detects light through a flavin chromophore within the N-terminal BLUF domain. BLUF domains have been found in a number of different light-activated proteins, but with different relative orientations. The two BLUF domains of OaPAC are found in close contact with each other, forming a coiled coil at their interface. Crystallization does not impede the activity switching of the enzyme, but flash cooling the crystals to cryogenic temperatures prevents the signature spectral changes that occur on photoactivation/deactivation. High-resolution crystallographic analysis of OaPAC in the fully activated state has been achieved by cryocooling the crystals immediately after light exposure. Comparison of the isomorphous light-and dark-state structures shows that the active site undergoes minimal changes, yet enzyme activity may increase up to 50-fold, depending on conditions. The OaPAC models will assist the development of simple, direct means to raise the cyclic AMP levels of living cells by light, and other tools for optogenetics.cAMP | BLUF domain | optogenetics | photoactivation | allostery

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Section: Discussionsupporting

confidence: 89%

Molecular mechanism of photoactivation of a light-regulated adenylate cyclase

Ohki

Sato‐Tomita

Matsunaga

et al. 2017

Proc. Natl. Acad. Sci. U.S.A.

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“…The broad band centered around 3212 cm −1 in NaOH-modified TiOF2 becomes broader than that in TiOF2, meaning that more O-H bonds or associated O-H appeared in NaOH-modified TiOF2. According to previous work, the free O-H stretching vibration used to appear at about 3600 cm −1 without bonding O-H [27,28]. It can be seen that the O-H frequency for TiOF2 and NaOH-modified TiOF2 is 221 cm −1 and 388 cm −1 lower than 3600 cm −1 , indicating a strong hydrogen bond impact [27,28].…”

Section: Phase Structures and Morphologymentioning

confidence: 86%

“…The strong band around 700-500 cm −1 could contribute to the Ti-O-Ti stretching vibration [22][23][24]. The peak around 3379 cm −1 and the broad band centered around 3212 cm −1 were due to the free and bonding O-H stretching vibration of Ti−OH, respectively [27,28]. The peak at 1620 cm −1 was due to the O-H bending vibration of Ti−OH [16,22,[29][30][31][32][33].…”

Section: Phase Structures and Morphologymentioning

confidence: 99%

“…According to previous work, the free O-H stretching vibration used to appear at about 3600 cm −1 without bonding O-H [27,28]. It can be seen that the O-H frequency for TiOF 2 and NaOH-modified TiOF 2 is 221 cm −1 and 388 cm −1 lower than 3600 cm −1 , indicating a strong hydrogen bond impact [27,28]. The O-H on the TiO 2 surface can enhance the transference of photo-generated electrons and then enhance photocatalytic performance [29].…”

Section: Phase Structures and Morphologymentioning

confidence: 99%

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Synthesis of NaOH-Modified TiOF2 and Its Enhanced Visible Light Photocatalytic Performance on RhB

2017

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NaOH-modified TiOF 2 was successfully prepared using a modified low-temperature hydrothermal method. Scanning electron microscopy shows that NaOH-modified TiOF 2 displayed a complex network shape with network units of about 100 nm. The structures of NaOH-modified TiOF 2 have not been reported elsewhere. The network shape permits the NaOH-modified TiOF 2 a S BET of 36 m 2 ·g −1 and a pore diameter around 49 nm. X-ray diffraction characterization shows that TiOF 2 and NaOH-modified TiOF 2 are crystallized with a pure changed cubic phase which accords with the SEM results. Fourier transform infrared spectroscopy characterization shows that NaOH-modified TiOF 2 has more O-H groups to supply more lone electron pairs to transfer from O of O-H to Ti and O of TiOF 2 . UV-vis diffuse reflectance spectroscopy (DRS) shows that the NaOH-modified TiOF 2 sample has an adsorption plateau rising from 400 to 600 nm in comparison with TiOF 2 , and its band gap is 2.62 eV, lower than that of TiOF 2 . Due to the lower band gap, more O-H groups adsorption, network morphologies with larger surface area, and sensitization progress, the NaOH-modified TiOF 2 exhibited much higher photocatalytic activity for Rhodamine B (RhB) degradation. In addition, considering the sensitization progress, O-H groups on TiOF 2 not only accelerated the degradation rate of RhB, but also changed its degradation path. As a result, the NaOH-modified TiOF 2 exhibited much higher photocatalytic activity for RhB degradation than the TiOF 2 in references under visible light. This finding provides a new idea to enhance the photocatalytic performance by NaOH modification of the surface of TiOF 2 .

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“…This is most likely predominantly facilitated by the rotation of the glutamine amide side chain (19,20) and leads to the red-shifted absorbance spectrum of the light-adapted state (5). Additionally, an unusually strong hydrogen bond is formed from the conserved tyrosine to the glutamine side chain (19,21). The molecular details of both dark-and light-adapted states as well as the implications for signal transduction are still under heavy debate because the available crystal structures of BLUF domains gave contradicting results, especially on the orientation of the glutamine side chain (22)(23)(24)(25)(26)(27).…”

mentioning

confidence: 99%

Redox Modulation of Flavin and Tyrosine Determines Photoinduced Proton-coupled Electron Transfer and Photoactivation of BLUF Photoreceptors

Mathes

Stokkum

Stierl

et al. 2012

Journal of Biological Chemistry

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Background: Proton-coupled electron transfer is the key step in BLUF photoactivation. Results: Redox modulation of flavin and tyrosine determines electron transfer rates and signaling efficiency and reveals a new photocycle intermediate. Conclusion:Partial charge transfer from tyrosine to flavin takes place prior to full electron transfer. Significance: Mechanistic details of protein-modulated electron transfer processes are crucial to understand biological protoncoupled electron transfer reactions.

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Strong Donation of the Hydrogen Bond of Tyrosine during Photoactivation of the BLUF Domain

Cited by 50 publications

References 34 publications

Molecular mechanism of photoactivation of a light-regulated adenylate cyclase

Molecular mechanism of photoactivation of a light-regulated adenylate cyclase

Synthesis of NaOH-Modified TiOF2 and Its Enhanced Visible Light Photocatalytic Performance on RhB

Redox Modulation of Flavin and Tyrosine Determines Photoinduced Proton-coupled Electron Transfer and Photoactivation of BLUF Photoreceptors

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