Tuning electron transfer by ester‐group of chlorophylls in bacterial photosynthetic reaction center

Ishikita, Hiroshi; Loll, Bernhard; Biesiadka, Jacek; Galstyan, Artur; Knapp, Ernst‐Walter

doi:10.1016/j.febslet.2004.12.049

Cited by 21 publications

(20 citation statements)

References 36 publications

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“…The procedures to obtain pK a of titratable residues are equivalent to those of the redox potential for redox-active groups, although in the latter case the Nernst equation is applied (31). Therefore, the accuracy of the present pK a computations is directly comparable to that obtained for recent computations on redoxactive cofactors (21)(22)(23). From the analogy, the numerical error of the pK a computation can be estimated to be Ϸ0.2 pH units.…”

supporting

confidence: 59%

“…In the present study, we calculated the protonation pattern of titratable residues in Cd-bRC based on the crystal structure (15) (8). Atomic coordinates were obtained in the same way as in previous applications (9,(21)(22)(23). The positions of hydrogen atoms were energetically optimized with CHARMM (24) by using the CHARMM22 force field.…”

mentioning

confidence: 99%

“…Atomic partial charges of the amino acids were adopted from the all-atom CHARMM22 (24) parameter set. For cofactors and residues whose charges are not available in CHARMM22, we used atomic partial charges from previous applications (21)(22)(23). For the atomic charges for the Cd 2ϩ -protein complex in Cd-bRC, see Supporting Text and Table 3, which are published as supporting information on the PNAS web site.…”

mentioning

confidence: 99%

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Induced conformational changes upon Cd ²⁺ binding at photosynthetic reaction centers

Ishikita

Knapp

2005

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

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Cd 2؉ binding at the bacterial photosynthetic reaction center (bRC) from Rhodobacter sphaeroides is known to inhibit proton transfer (PT) from bulk solvent to the secondary quinone Q B. To elucidate this mechanism, we calculated the pK a for residues along the water channels connecting Q B with the stromal side based on the crystal structures of WT-bRC and Cd 2؉ -bound bRC. Upon Cd 2؉ binding, we observed the release of two protons from His-H126͞128 at the Cd 2؉ binding site and significant pKa shifts for residues along the PT pathways. Remarkably, Asp-L213 near Q B, which is proposed to play a significant role in PT, resulted in a decrease in pK a upon Cd 2؉ binding. The direct electrostatic influence of the Cd 2؉ -positive charge on these pK a shifts was small. Instead, conformational changes of amino acid side chains induced electrostatically by Cd 2؉ binding were the main mechanism for these pKa shifts. The longrange electrostatic influence over Ϸ12 Å between Cd 2؉ and Asp-L213 is likely to originate from a set of Cd 2؉ -induced successive reorientations of side chains (Asp-H124, His-H126, His-H128, Asp-H170, Glu-H173, Asp-M17, and Asp-L210), which propagate along the PT pathways as a ''domino'' effect.Cd͞Zn binding effect ͉ photosystem ͉ proton uptake ͉ revertant mutants ͉ secondary quinone

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supporting

confidence: 59%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Induced conformational changes upon Cd ²⁺ binding at photosynthetic reaction centers

Ishikita

Knapp

2005

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

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“…viridis ÒÑÍÂÊÞÄÂáÕ, ÚÕÑ ¡-ÄÇÕÄß ËÏÇÇÕ ÊÐÂÚËÕÇÎßÐÑ ÃÑÎß-ÛËÌ ÒÑÎÑÉËÕÇÎßÐÞÌ ÒÑÕÇÐÙËÂÎ, ÚÇÏ £-ÄÇÕÄß, ÚÕÑ âÄ-ÎâÇÕÔâ ÇÜÈ ÑAEÐÑÌ ÒÓËÚËÐÑÌ ÒÇÓÇÐÑÔÂ àÎÇÍÕÓÑÐÂ ÒÓÇË-ÏÖÜÇÔÕÄÇÐÐÑ ÒÑ ¡-ÄÇÕÄË [94]. £ ÓÂÔÚÈÕÂØ ÒÑÍÂÊÂÐÑ, ÚÕÑ ÑÓËÇÐÕÂÙËâ 13 2 -à×ËÓÐÑÌ ÅÓÖÒÒÞ BChl ÑÍÂÊÞÄÂÇÕ ÔËÎßÐÑÇ ÄÎËâÐËÇ ÐÂ àÎÇÍÕÓÑÔÕÂÕËÚÇÔÍËÇ ÒÑÕÇÐÙËÂÎÞ [189]. ²ÂÔ-ÚÈÕÞ ÒÑAEÕÄÇÓÉAEÂáÕ ØÑÓÑÛÑ ËÊÄÇÔÕÐÞÌ àÍÔÒÇÓËÏÇÐÕÂÎß-ÐÞÌ ×ÂÍÕ: ÒÑÕÇÐÙËÂÎ E m AEÎâ ÒÇÓÄËÚÐÑÅÑ AEÑÐÑÓÂ àÎÇÍ-ÕÓÑÐÑÄ ×ÑÕÑÔËÔÕÇÏÞ II ²680 ÐÂÏÐÑÅÑ ÃÑÎßÛÇ, ÚÇÏ AEÎâ P Ä ÃÂÍÕÇÓËÂÎßÐÞØ ²¸ [190].…”

unclassified

Physical stage of photosynthesis charge separation

Yakovlev¹,

Шувалов²

2016

Usp. Fiz. Nauk

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“…For these mutants direct PT between Glu-203 and Glu-148 would have to bridge a gap of about 15 Å. This may be within range of long distance electron tunneling processes (15) such as those in photosynthetic proteins (16,17) but is inconceivable for protons with their much larger mass. A pore-searching algorithm on EClC led to identification of two potential PT pathways, namely P1 and P2 (18).…”

mentioning

confidence: 99%

Charge Transport in the ClC-type Chloride-Proton Anti-porter from Escherichia coli

Kieseritzky¹,

Knapp

2011

Journal of Biological Chemistry

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The first chloride transporter identified in the superfamily of ClC chloride channels was from Escherichia coli (EClC) (Accardi, A., and Miller, C. (2004) Nature 427, 803-807). Pathways, energetics, and mechanism of proton and chloride translocation and their coupling are up to now unclear. To bridge the hydrophobic gap of proton transport, we modeled four stable buried waters into both subunits of the WT EClC structure. Together they form a "water wire" connecting Glu-203 with the chloride at the central site, which in turn connects to Glu-148, the hypothetical proton exit site. Assuming the transient production of hydrochloride in the central chloride binding site of EClC, the water wire could establish a transmembrane proton transport pathway starting from Glu-203 all the way downstream onto Glu-148. We demonstrated by electrostatic and quantum chemical computations that protonation of the central chloride is energetically feasible. We characterized all chloride occupancies and protonation states possibly relevant for the proton-chloride transport cycle in EClC and constructed a working model. Accordingly, EClC evolves through states involving up to two excess protons and between one and three chlorides, which was required to fulfill the experimentally observed 2:1 stoichiometry. We show that the Y445F and E203H mutants of EClC can operate similarly, thus explaining why they exhibit almost WT activity levels. The proposed mechanism of coupled chloride-proton transport in EClC is consistent with available experimental data and allows predictions on the importance of specific amino acids, which may be probed by mutation experiments.

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Tuning electron transfer by ester‐group of chlorophylls in bacterial photosynthetic reaction center

Cited by 21 publications

References 36 publications

Induced conformational changes upon Cd ²⁺ binding at photosynthetic reaction centers

Induced conformational changes upon Cd ²⁺ binding at photosynthetic reaction centers

Physical stage of photosynthesis charge separation

Charge Transport in the ClC-type Chloride-Proton Anti-porter from Escherichia coli

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Tuning electron transfer by ester‐group of chlorophylls in bacterial photosynthetic reaction center

Cited by 21 publications

References 36 publications

Induced conformational changes upon Cd 2+ binding at photosynthetic reaction centers

Induced conformational changes upon Cd 2+ binding at photosynthetic reaction centers

Physical stage of photosynthesis charge separation

Charge Transport in the ClC-type Chloride-Proton Anti-porter from Escherichia coli

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Induced conformational changes upon Cd ²⁺ binding at photosynthetic reaction centers

Induced conformational changes upon Cd ²⁺ binding at photosynthetic reaction centers