Changes in Structural and Functional Properties of Oxygen-evolving Complex Induced by Replacement of D1-Glutamate 189 with Glutamine in Photosystem II

Abstract

A carboxylate group of D1-Glu-189 in photosystem II has been proposed to serve as a direct ligand for the manganese cluster. Here we constructed a mutant that eliminates the carboxylate by replacing D1-Glu-189 with Gln in the cyanobacterium Synechocystis sp. PCC 6803, and we examined the resulting effects on the structural and functional properties of the oxygen-evolving complex (OEC) in photosystem II. The E189Q mutant grew photoautotrophically, and isolated photosystem II core particles evolved oxygen at ∼70% of the rate of control wild-type particles. The E189Q OEC showed typical S2 state electron spin resonance signals, and the spin center distance between the S2 state manganese cluster and the YD (D2-Tyr-160), detected by electron-electron double resonance spectroscopy, was not affected by this mutation. However, the redox potential of the E189Q OEC was considerably lower than that of the control OEC, as revealed by the elevated peak temperature of the S2 state thermoluminescence bands. The mutation resulted in specific changes to bands ascribed to the putative carboxylate ligands for the manganese cluster and to a few carbonyl bands in mid-frequency (1800 to 1100 cm−1) S2/S1 Fourier transform infrared difference spectrum. Notably, the low frequency (650 to 350 cm−1) S2/S1 Fourier transform infrared difference spectrum was also uniquely changed by this mutation in the frequencies for the manganese cluster core vibrations. These results suggested that the carboxylate group of D1-Glu-189 ligates the manganese ion, which is influenced by the redox change of the oxidizable manganese ion upon the S1 to S2 transition. A carboxylate group of D1-Glu-189 in photosystem II has been proposed to serve as a direct ligand for the manganese cluster. Here we constructed a mutant that eliminates the carboxylate by replacing D1-Glu-189 with Gln in the cyanobacterium Synechocystis sp. PCC 6803, and we examined the resulting effects on the structural and functional properties of the oxygen-evolving complex (OEC) in photosystem II. The E189Q mutant grew photoautotrophically, and isolated photosystem II core particles evolved oxygen at ∼70% of the rate of control wild-type particles. The E189Q OEC showed typical S2 state electron spin resonance signals, and the spin center distance between the S2 state manganese cluster and the YD (D2-Tyr-160), detected by electron-electron double resonance spectroscopy, was not affected by this mutation. However, the redox potential of the E189Q OEC was considerably lower than that of the control OEC, as revealed by the elevated peak temperature of the S2 state thermoluminescence bands. The mutation resulted in specific changes to bands ascribed to the putative carboxylate ligands for the manganese cluster and to a few carbonyl bands in mid-frequency (1800 to 1100 cm−1) S2/S1 Fourier transform infrared difference spectrum. Notably, the low frequency (650 to 350 cm−1) S2/S1 Fourier transform infrared difference spectrum was also uniquely changed by this mutation in the frequencies for the manganese cluster core vibrations. These results suggested that the carboxylate group of D1-Glu-189 ligates the manganese ion, which is influenced by the redox change of the oxidizable manganese ion upon the S1 to S2 transition. Photosynthetic water oxidation occurs in an oxygen-evolving complex (OEC), 4The abbreviations used are: OECoxygen-evolving complexPSphotosystemChlchlorophyllQAprimary quinone acceptorFTIRFourier transform infraredESE ELDORelectron spin echo electron-electron double resonanceDCMU3-(3,4-dichlorophenyl)-1,1-dimethylureaMes2-morpholinoethanesulfonic acid 4The abbreviations used are: OECoxygen-evolving complexPSphotosystemChlchlorophyllQAprimary quinone acceptorFTIRFourier transform infraredESE ELDORelectron spin echo electron-electron double resonanceDCMU3-(3,4-dichlorophenyl)-1,1-dimethylureaMes2-morpholinoethanesulfonic acid which contains a catalytic center composed of four manganese ions and an associated Ca2+ ion located on the luminal side of the D1/D2 heterodimer in photosystem (PS) II (1Debus R.J. Biochim. Biophys. Acta. 1992; 1102: 269-352Crossref PubMed Scopus (1084) Google Scholar). The OEC converts two water molecules to one oxygen molecule through a light-driven reaction cycle with five intermediate states denoted Sn (n = 0-4), where n represents the number of stored oxidizing equivalents. In the dark, the OEC is predominantly in a thermally stable S1 state and advances to the next oxidation state, S2, by absorbing a photon. The OEC reaches the highest oxidation state, S4, by accumulating four oxidizing equivalents after three flashes and then relaxes to the lowest oxidation state, S0, concurrent with the release of an oxygen molecule (2Joliot P. Barbieri G. Chabaud R. Photochem. Photobiol. 1969; 10: 309-329Crossref Scopus (520) Google Scholar, 3Kok B. Forbush B. McGloin M.P. Photochem. Photobiol. 1970; 11: 457-475Crossref PubMed Scopus (1809) Google Scholar). oxygen-evolving complex photosystem chlorophyll primary quinone acceptor Fourier transform infrared electron spin echo electron-electron double resonance 3-(3,4-dichlorophenyl)-1,1-dimethylurea 2-morpholinoethanesulfonic acid oxygen-evolving complex photosystem chlorophyll primary quinone acceptor Fourier transform infrared electron spin echo electron-electron double resonance 3-(3,4-dichlorophenyl)-1,1-dimethylurea 2-morpholinoethanesulfonic acid Site-directed mutagenesis studies using the cyanobacterium Synechocystis sp. PCC 6803 (reviewed in Refs. 4Diner B.A. Biochim. Biophys. Acta. 2001; 1503: 147-163Crossref PubMed Scopus (172) Google Scholar and 5Debus R.J. Biochim. Biophys. Acta. 2001; 1503: 164-186Crossref PubMed Scopus (183) Google Scholar) have revealed that replacement of amino acid residues by another residue affects the properties of the OEC. These amino acids include Asp-170, Glu-189, His-190, His-332, Glu-333, His-337, Asp-342, and Ala-344 of the D1 protein (6Nixon P.J. Diner B.A. Biochemistry. 1992; 31: 942-948Crossref PubMed Scopus (224) Google Scholar, 7Nixon P.J. Trost J.T. Diner B.A. Biochemistry. 1992; 31: 10859-10871Crossref PubMed Scopus (194) Google Scholar, 8Chu H.-A. Nguyen A.P. Debus R.J. Biochemistry. 1994; 33: 6137-6149Crossref PubMed Scopus (134) Google Scholar, 9Nixon P.J. Diner B.A. Biochem. Soc. Trans. 1994; 22: 338-343Crossref PubMed Scopus (61) Google Scholar, 10Chu H.-A. Nguyen A.P. Debus R.J. Biochemistry. 1995; 34: 5839-5858Crossref PubMed Scopus (183) Google Scholar, 11Chu H.-A. Nguyen A.P. Debus R.J. Biochemistry. 1995; 34: 5859-5882Crossref PubMed Scopus (116) Google Scholar). Some residues are arranged in close proximity to the manganese cluster, as shown by x-ray crystallographic models (12Zouni A. Witt H.T. Kern J. Fromme P. Krauss N. Saenger W. Orth P. Nature. 2001; 409: 739-743Crossref PubMed Scopus (1755) Google Scholar, 13Kamiya N. Shen J.-R. Proc. Natl. Acad. Sci. U. S. A. 2003; 100: 98-103Crossref PubMed Scopus (991) Google Scholar, 14Ferreira K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar, 15Biesiadka J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar), suggesting that the manganese cluster is coordinated mainly with carboxylate and imidazole groups from these residues in the D1 protein. Several carboxylate and histidine ligands were characterized spectroscopically using a combination of site-directed mutagenesis and isotope labeling. The replacement of D1-Asp-170 with His resulted in marked changes in the low frequency (650 to 500 cm−1) S2/S1 Fourier transform infrared (FTIR) spectrum (16Chu H.-A. Debus R.J. Babcock G.T. Biochemistry. 2001; 40: 2312-2316Crossref PubMed Scopus (71) Google Scholar); however, this substitution induced no change in the S1 and S2 multiline electron spin resonance (ESR) signals (17Debus R.J. Aznar C. Campbell K.A. Gregor W. Diner B.A. Britt R.D. Biochemistry. 2003; 42: 10600-10608Crossref PubMed Scopus (42) Google Scholar) or in the mid-frequency FTIR difference spectra for the S1 to S2 (16Chu H.-A. Debus R.J. Babcock G.T. Biochemistry. 2001; 40: 2312-2316Crossref PubMed Scopus (71) Google Scholar, 18Debus R.J. Strickler M.A. Walker L.M. Hillier W. Biochemistry. 2005; 44: 1367-1374Crossref PubMed Scopus (109) Google Scholar) and other R.J. Strickler M.A. Walker L.M. Hillier W. Biochemistry. 2005; 44: 1367-1374Crossref PubMed Scopus (109) Google Scholar). that the carboxylate side group of D1-Asp-170 ligates the manganese ion that not a redox change the state R.J. Strickler M.A. Walker L.M. Hillier W. Biochemistry. 2005; 44: 1367-1374Crossref PubMed Scopus (109) Google Scholar). bands for the carboxylate of in the H.-A. W. Debus R.J. Biochemistry. 2004; 42: Scopus Google Scholar, N. A. J. Chem. 2005; PubMed Scopus Google Scholar) and low frequency N. A. J. Chem. 2005; PubMed Scopus Google Scholar) S2/S1 FTIR the of the carboxylate to the manganese replacement of the side group of with another group induced changes in OEC properties N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar, N. A. S. Biochemistry. 2004; PubMed Scopus Google Scholar). changes of the bands showed that the manganese ion associated with the carboxylate is upon the S1 to S2 and the to N. A. J. Chem. 2005; PubMed Scopus Google Scholar). The carboxylate was not in the electron of the was to to a Ca2+ ion K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar). However, FTIR studies showed that Ca2+ induced change of the carboxylate for the carboxylate 2005; PubMed Scopus Google Scholar). the of the carboxylate to a manganese ion not to a Ca2+ ion was by the FTIR using Synechocystis in which was with M.A. Walker L.M. Hillier W. Debus R.J. Biochemistry. 2005; 44: PubMed Scopus Google Scholar). The of histidine to the manganese cluster is suggested on electron spin echo Diner B.A. Britt R.D. Proc. Natl. Acad. Sci. U. S. A. 1994; PubMed Scopus Google Scholar) and FTIR Biochemistry. PubMed Scopus Google Scholar) studies for the cyanobacterium Synechocystis sp. PCC 6803 a histidine two in the imidazole models showed that the carboxylate side group of D1-Glu-189 as a ligand for the manganese cluster K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar, 15Biesiadka J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar), the models were to other the J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar) and K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar) of the to The II isolated from and evolved no oxygen the functional reaction R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar). In these an S1 an S2 multiline was however, an state was the of and R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar) a change in the redox potential of in these was then proposed that D1-Glu-189 is of a and the manganese cluster for from the manganese cluster to R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar). In the and grew with oxygen with wild-type R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar). showed electron from to as as from the manganese cluster to J. S. Debus R.J. W. Biochim. Biophys. Acta. 2001; PubMed Scopus Google Scholar), and the II isolated from E189Q S1 and S2 multiline signals R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar). The OEC properties in these to with the proposed of the D1-Glu-189 carboxylate for the manganese ion as as to the carboxylate group is in the and the residue was with a or the structural and functional of D1-Glu-189 are In the we constructed the Synechocystis which the carboxylate side group is to structural The structural and functional properties of the mutant were examined by of and FTIR in isolated II core particles. The mutation induced changes in the properties of the manganese cluster resulted in the changes in the redox potential and of the manganese cluster. on these and other the structural and functional of D1-Glu-189 are of Synechocystis sp. PCC 6803 for site-directed mutagenesis was constructed by replacing a of and with to and and a was to the of the protein N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). were the of Synechocystis sp. PCC 6803 in which a to of the as N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). of the was changed to A the mutation was the of Synechocystis sp. PCC 6803, and were for on a wild-type control a the wild-type was the Synechocystis were in with at of were using a and the resulting were with and II particles were on a acid as N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). The core particles were with A and with and in A after with A. of protein II core particles were with by using on a N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). FTIR (1800 to 1100 cm−1) FTIR spectra were on a with an N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). frequency (650 to 350 cm−1) FTIR spectra were on a with a N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). II core particles in a and were at for and a of of the resulting was with of as an electron acceptor on a for mid-frequency or an for low frequency temperature was at using a N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). were with a from a with of at the spectra were at in the mid-frequency or low frequency and after and difference spectra were mid-frequency difference spectra or low frequency difference spectra were and were on a with a or core particles were in a and and to of to a and at for with temperature for was using a temperature control or a was used as A. Biochim. Biophys. Acta. Scopus Google Scholar) with of and for the and A was used as the were as N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). and II core particles were in A at of in the of and at with a The was using a oxygen in A at in the of and for or for core particles as N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). the effects of the E189Q mutation on and The mutant grew and low and showed the were lower than of the wild-type The II core particles isolated from the mutant showed which was lower to that from the wild-type in with the in and These properties of the E189Q mutant were with R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google and II in wild-type control and of Synechocystis sp. PCC are of of are of are of II in the in and II core particles from the low were used for of oxygen are of are of are of of in the in and II core particles from the low were used for of oxygen in a The of the II core particles N. A. S. and showed no difference in protein between wild-type control and the E189Q mutant in of and of as as three and is that the lower in the mutant core particles is not ascribed to in the protein change in the properties of the OEC induced by the mutation. the thermoluminescence of the and II core particles in the wild-type control and E189Q mutant The wild-type showed an at with that N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar). The peak temperature of the in the mutant was elevated to The wild-type and mutant II core particles showed bands at and Notably, the peak temperature was in the mutant which with in the thermoluminescence bands of the the bands at a temperature for the core particles than the in the and to II between the and core particles are to the The results that the redox potential of the S2 state manganese cluster was by replacement of D1-Glu-189 with which for the in the as shown in the effects of the mutation on the S2 state spectra for the wild-type control and E189Q mutant II core particles. spectra showed a = S2 multiline and at = and a = S2 the of the multiline in the mutant spectrum was ∼70% that of the control spectrum. the multiline is not ascribed to the of the multiline to the = S2 change in the of the multiline by the mutation is with the results R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar). The results that the of the S2 state manganese cluster was not affected by replacement of with The of the putative carboxylate ligand for the manganese ion in the E189Q mutant in a change of the manganese cluster in II the carboxylate is for the of the manganese cluster, the was not affected by the mutation. this mutation effects on the distance between YD and the manganese cluster were the and spectra for the of composed of the of YD and S2 multiline center of the manganese cluster in the wild-type control and E189Q mutant II core particles. The distance between the two was to with an of for the wild-type and the mutant that the mutation not change of the manganese cluster in we the that the of the manganese cluster on a by the from YD was Notably, the distance was than that in A. Biochim. Biophys. Acta. Scopus Google Scholar), suggesting a difference in the of the manganese cluster between and the mid-frequency (1800 to 1100 cm−1) S2/S1 FTIR difference spectra of the wild-type control and E189Q mutant II core particles. The wild-type spectrum showed S2/S1 as to cm−1) and to cm−1) from the putative carboxylate ligands for the manganese cluster as as to cm−1) and II to cm−1) from N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). The E189Q spectrum showed S2/S1 to of wild-type spectrum in were in the carboxylate S2/S1 carboxylate bands at were by this resulting in the of bands at other carboxylate bands not change and at the as in the wild-type spectrum. of the carboxylate and II bands were not affected by the with the of changes to In bands at to in the E189Q spectrum were from in the wild-type of the at and peak was to the changes induced by the E189Q mutation a double difference spectrum was by the E189Q spectrum from the wild-type spectrum after with to of cm−1) and cm−1) bands N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). The E189Q spectrum carboxylate bands that were resulting in the bands at and in the double difference however, no lower than for bands at In the to bands at and the bands at to include of the of and water bands. is of that the which was to the of the histidine ligand for the manganese cluster Biochemistry. PubMed Scopus Google Scholar), was affected by the E189Q mutation. models that ligates the manganese ion associated with D1-Glu-189 K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar, 15Biesiadka J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar), and the redox and properties of manganese cluster and are in the mutant R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar, R.J. Campbell K.A. W. Britt R.D. Biochemistry. 2001; 40: PubMed Scopus Google Scholar). However, no difference in a histidine at that the between and the manganese cluster was not affected by the mutation. the low frequency (650 to 350 cm−1) S2/S1 FTIR difference spectra of the wild-type control and E189Q mutant II core particles. The wild-type spectrum showed low frequency S2/S1 as bands at and as as to low with N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). The and bands were ascribed to the of and N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). The E189Q spectrum showed a marked difference from the wild-type spectrum at to however, no difference was detected The effects on the S2/S1 induced by the E189Q mutation in the double difference spectrum by the E189Q spectrum from the wild-type spectrum after with the that was used for the double of the mid-frequency The double difference spectrum a composed of three bands at and The using water A. Biochemistry. 2005; 44: PubMed Scopus Google Scholar) that this few putative cluster at and A. Biochemistry. 2005; 44: PubMed Scopus Google Scholar, H.-A. Babcock G.T. Biochemistry. PubMed Scopus Google Scholar) as as of the manganese cluster or the at N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). the marked changes in that changes in the of the manganese cluster are induced by replacement of a ligand to the manganese ion from D1-Glu-189 to Gln than through The results that structural properties of the manganese cluster were with a change in by Gln for at of the D1 protein. The mid-frequency FTIR spectrum of the E189Q mutant II core particles showed changes of the specific bands in the at to for the putative carboxylate these changes are the direct of the of the carboxylate group for manganese or ascribed to structural induced by the of the carboxylate through the in carboxylate which is not a ligand to the manganese cluster is located in the of the cluster. bands for the carboxylate the change in the upon the substitution no change in the peak Biochim. Biophys. Acta. 1995; Scopus Google Scholar). However, the to bands affected by the E189Q mutation not change in the as as in the peak by the Biochemistry. PubMed Scopus Google Scholar), suggesting that the is an was no carboxylate ligand that with through in the x-ray crystallographic models K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar, 15Biesiadka J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar). a is that the of the carboxylate the manganese ion in the to and of the is for the bands in the double difference spectrum The E189Q mutation resulted in marked changes of the low frequency S2/S1 bands in the to bands for manganese cluster core the at A. Biochemistry. 2005; 44: PubMed Scopus Google Scholar, H.-A. Babcock G.T. Biochemistry. PubMed Scopus Google Scholar) and the of the manganese cluster or of the at N. A. Biochemistry. 2003; 42: PubMed Scopus Google Scholar). is to the in the affects the core of the manganese cluster changes in the of the manganese cluster the mutation specific change in a specific ligand for the manganese the changes of the low frequency bands the in the of the manganese cluster induced by replacement of a ligand to the manganese ion from D1-Glu-189 to Gln than by the of the manganese cluster in this the and low frequency FTIR results the direct of the carboxylate group of D1-Glu-189 with the manganese The of the carboxylate ligand induced structural which for the in the oxidation potential of the S2 state manganese cluster and the in of the and These the of the x-ray structural in which the carboxylate side group of D1-Glu-189 as a ligand to the manganese cluster. In to the to no changes to the mutation were at to where of a carboxylate that ligates a ion in a are to suggesting of the carboxylate to the manganese the in the x-ray models K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar, 15Biesiadka J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar). that the two x-ray models in of the which the manganese ion and of in one J. Loll B. Kern J. Irrgang K.-D. Zouni A. Phys. Chem. Chem. Phys. 2004; 6: 4733-4736Crossref Scopus (263) Google Scholar) not in the other K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar). that the is upon x-ray a the an of the FTIR results the to the is to a of the carboxylate R.J. Chem. 33: Scopus Google Scholar). However, this not to the the carboxylate bands at to were not influenced by the substitution Biochim. Biophys. Acta. 1995; Scopus Google Scholar, Biochemistry. PubMed Scopus Google Scholar). difference in the for lower than that the carboxylate is not associated with the manganese ion by the of the of the at in the S1 state and at in the S2 state H.-A. W. Debus R.J. Biochemistry. 2004; 42: Scopus Google Scholar, N. A. J. Chem. 2005; PubMed Scopus Google Scholar). is by the that the replacement of the side group of with another group N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar, N. A. S. Biochemistry. 2004; PubMed Scopus Google Scholar) induced changes in carboxylate bands at to not at to where the changes by the E189Q mutation were induced as shown in an x-ray no of the Ala-344 carboxylate with a manganese ion, which is by the carboxylate K.N. Iverson T.M. Maghlaoui K. Barber J. Iwata S. Science. 2004; 303: 1831-1833Crossref PubMed Scopus (2831) Google Scholar). the manganese ion by the D1 is proposed to the from the S1 to S2 state H.-A. W. Debus R.J. Biochemistry. 2004; 42: Scopus Google Scholar, N. A. J. Chem. 2005; PubMed Scopus Google Scholar, N. A. S. J. Chem. 2004; PubMed Scopus Google Scholar, N. A. S. Biochemistry. 2004; PubMed Scopus Google Scholar, M.A. Walker L.M. Hillier W. Debus R.J. Biochemistry. 2005; 44: PubMed Scopus Google Scholar), the D1-Glu-189 carboxylate serve as a ligand for the manganese ion that is not upon the S1 to S2 is with the manganese ion the S1 to S2 transition. a change in of the manganese cluster from the x-ray P. U. J. W. G. J. Chem. Soc. 2004; PubMed Scopus Google Scholar) to the of the carboxylate to D1-Glu-189 as as to in the S2/S1 difference spectrum. Notably, the properties of the E189Q mutant are with that in the mutant (16Chu H.-A. Debus R.J. Babcock G.T. Biochemistry. 2001; 40: 2312-2316Crossref PubMed Scopus (71) Google Scholar, 18Debus R.J. Strickler M.A. Walker L.M. Hillier W. Biochemistry. 2005; 44: 1367-1374Crossref PubMed Scopus (109) Google Scholar). The mutant showed no difference in the mid-frequency (1800 to cm−1) FTIR difference spectra for the S1 to to to S0, and to S1 and in the S1 and S2 state multiline signals, the low frequency S2/S1 bands for the were affected by this mutation. D1-Asp-170 ligates the manganese ion and is not with the other manganese functional of a S2 multiline and a of change in the of the spin center of the S2 state manganese cluster that the manganese associated with the D1-Glu-189 carboxylate is by another amino acid side group or with a close to the carboxylate in the E189Q is a at in the mid-frequency double difference spectrum where the carbonyl of A. Biophys. PubMed Scopus Google Scholar). In were to at in the spectrum of II core particles from the mutant R. A. J. Diner B.A. C. Biochemistry. PubMed Scopus Google Scholar). these results that the carbonyl group of as a ligand for the manganese ion in the E189Q studies have that showed with in where D1-Glu-189 was with or R.J. Campbell K.A. Britt R.D. Biochemistry. PubMed Scopus Google Scholar). The carbonyl is for manganese in these in the E189Q mutant the side group carbonyl of in a to the side group carboxylate of to serve as a direct of D1-Glu-189 is as a acceptor from through or C. Babcock G.T. Chem. 31: Scopus Google Scholar, C. Babcock G.T. Biochim. Biophys. Acta. PubMed Scopus Google Scholar). However, no change was induced by the E189Q mutation in the to where the of the group of acid A. Biophys. PubMed Scopus Google Scholar). of is a at the S1 to S2 with in the E189Q mutant that no contains a carboxylate at has been proposed that the or in the S2/S1 spectrum to the or of the on the effects of isotope Biochemistry. PubMed Scopus Google Scholar). the double difference bands at and in to the which are changed by the E189Q mutation. However, we have not these in in the for the of the bands in the spectrum. In replacement of D1-Glu-189 with Gln induced changes in the of the manganese cluster, as by in the carboxylate and in manganese cluster core The results suggested that the D1-Glu-189 carboxylate as a direct ligand for the manganese ion, which is influenced by the redox change of the oxidizable manganese ion upon the S1 to S2 and not in the reaction from to the luminal of the II the S1 to S2 transition.