Abstract:
:The electronic structure of a Mn(II) ion bound to highly oxidizing reaction centers of Rhodobacter sphaeroides was studied in a mutant modified to possess a metal binding site at a location comparable to the Mn4Ca cluster of photosystem II. The Mn-binding site of the previously described mutant, M2, contains three carboxylates and one His at the binding site (Thielges et al., Biochemistry 44:389-7394, 2005). The redox-active Mn-cofactor was characterized using electron paramagnetic resonance (EPR) and electron spin echo envelope modulation (ESEEM) spectroscopies. In the light without bound metal, the Mn-binding mutants showed an EPR spectrum characteristic of the oxidized bacteriochlorophyll dimer and reduced quinone whose intensity was significantly reduced due to the diminished quantum yield of charge separation in the mutant compared to wild type. In the presence of the metal and in the dark, the EPR spectrum measured at the X-band frequency of 9.4 GHz showed a distinctive spin 5/2 Mn(II) signal consisting of 16 lines associated with both allowed and forbidden transitions. Upon illumination, the amplitude of the spectrum is decreased by over 80 % due to oxidation of the metal upon electron transfer to the oxidized bacteriochlorophyll dimer. The EPR spectrum of the Mn-cofactor was also measured at the Q-band frequency of 34 GHz and was better resolved as the signal was composed of the six allowed electronic transitions with only minor contributions from other transitions. A fit of the Q-band EPR spectrum shows that the Mn-cofactor is a high spin Mn(II) species (S = 5/2) that is six-coordinated with an isotropic g-value of 2.0006, a weak zero-field splitting and E/D ratio of approximately 1/3. The ESEEM experiments showed the presence of one (14)N coordinating the Mn-cofactor. The nitrogen atom is assigned to a His by comparing our ESEEM results to those previously reported for Mn(II) ions bound to other proteins and on the basis of the X-ray structure of the M2 mutant that shows the presence of only one His, residue M193, that can coordinate the Mn-cofactor. Together, the data allow the electronic structure and coordination environment of the designed Mn-cofactor in the modified reaction centers to be characterized in detail and compared to those observed in other proteins with Mn-cofactors.
journal_name
Photosynth Resjournal_title
Photosynthesis researchauthors
Tufts AA,Flores M,Olson TL,Williams JC,Allen JPdoi
10.1007/s11120-013-9887-1subject
Has Abstractpub_date
2014-05-01 00:00:00pages
207-20issue
1-2eissn
0166-8595issn
1573-5079journal_volume
120pub_type
杂志文章abstract::P700 enriched fractions were isolated from two brown algae and one diatom using sucrose density centrifugation after digitinin solubilization. They had a Chl a/P700 ratio of about 250 to 375 according to the species, they were enriched in long-wavelength absorbing Chl a and exhibited a fluorescence emission maximum at...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00035009
更新日期:1990-02-01 00:00:00
abstract::The effect of acetate metabolism on the light energy distribution between the two photosystems, on the PS II/PS I stoichiometry and on the expression of psbA and psbB and psaA genes was investigated in the green alga, Chlamydobotrys stellata during autotrophic (CO(2)), mixotrophic (CO(2) plus acetate) and photoheterot...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1023/A:1010650532693
更新日期:2000-01-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00042009
更新日期:1991-12-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00016274
更新日期:1993-05-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00032785
更新日期:1985-01-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-011-9712-7
更新日期:2012-02-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-018-0579-8
更新日期:2019-05-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-007-9274-x
更新日期:2008-04-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-014-0044-2
更新日期:2015-02-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00035379
更新日期:1991-08-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF02187123
更新日期:1994-11-01 00:00:00
abstract::Acaryochloris marina is a unique cyanobacterium that contains chlorophyll (Chl) d as a major pigment. Because Chl d has smaller excitation energy than Chl a used in ordinary photosynthetic organisms, the energetics of the photosystems of A. marina have been the subject of interest. It was previously shown that the red...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-014-0073-x
更新日期:2015-08-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1023/A:1024962328483
更新日期:2003-01-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00037179
更新日期:1989-09-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00117671
更新日期:1987-01-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章,评审
doi:10.1007/s11120-013-9828-z
更新日期:2013-11-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 传,历史文章,杂志文章
doi:10.1007/s11120-017-0440-5
更新日期:2018-04-01 00:00:00
abstract::Recently, microalgae have attracted attention as sources of biomass energy. However, fatty acids from the microalgae are mainly unsaturated and show low stability in oxygenated environments, due to oxidation of the double bonds. The branched-chain fatty acid, 10-methyl stearic acid, is synthesized from oleic acid in c...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-018-0537-5
更新日期:2019-03-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-015-0176-z
更新日期:2016-01-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
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更新日期:2018-04-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00034857
更新日期:1990-03-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章,评审
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更新日期:2011-09-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-015-0128-7
更新日期:2015-06-01 00:00:00
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journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-007-9156-2
更新日期:2007-07-01 00:00:00
abstract::Unique light-harvesting antennas in the green sulfur bacterium Chlorobaculum tepidum, called chlorosomes, consist of self-aggregates of bacteriochlorophyll (BChl) c. In the biosynthesis of BChl c, BciC demethoxycarbonylase removes the C132-methoxycarbonyl group to facilitate the self-aggregation of BChl c. We previous...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-018-0573-1
更新日期:2019-03-01 00:00:00
abstract::Photoacclimation by strains of Haslea "blue" diatom species H. ostrearia and H. silbo sp. nov. ined. was investigated with rapid light curves and induction-recovery curves using fast repetition rate fluorescence. Cultures were grown to exponential phase under 50 µmol m-2 s-1 photosynthetic available radiation (PAR) an...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-018-0508-x
更新日期:2018-09-01 00:00:00
abstract::Application of target theory to the photoinactivation of Photosystem II in pea leaf discs (Park et al. 1995, 1996a,b) reveals that there is a critical light dosage below which there is complete photoprotection and above which there is photoinactivation (i.e a light-induced loss of oxygen flash yield). The critical dos...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00018219
更新日期:1996-10-01 00:00:00
abstract::A combination of inhibitor and (15)N studies were used to investigate the photorespiratory nitrogen cycle in maize, a C4 plant. Inhibitors used included isonicotinyl hydrazide which blocks the conversion of glycine to serine, methionine sulfoximine an inhibitor of GS and azaserine an inhibitor of GOGAT. Results from l...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/BF00041796
更新日期:1983-01-01 00:00:00
abstract::Rhodobacter sphaeroides 2.4.1 is an alpha-3 purple nonsulfur eubacterium with an extensive metabolic repertoire. Under anaerobic conditions, it is able to grow by photosynthesis, respiration and fermentation. Photosynthesis may be photoheterotrophic using organic compounds as both a carbon and a reducing source, or ph...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1023/A:1013831823701
更新日期:2001-01-01 00:00:00
abstract::In order to evaluate genotypic variation, we measured leaf photosynthetic rate (Pn) and its associated factors for the rice diversity research set of germplasm (RDRS) selected from the Genebank in National Institute of Agrobiological Sciences (NIAS). Pn showed large genotypic variation from 11.9 to 32.1 micromol m(-2 ...
journal_title:Photosynthesis research
pub_type: 杂志文章
doi:10.1007/s11120-007-9208-7
更新日期:2007-10-01 00:00:00