Photosystem core complex

Nakazato K, Ichimwa T, Mayanagi K, Ishikawa T, Inoue Y. Atomic force microscopy of two-dimensional crystal of photosystem II core complex. Plant Cell Physiol 1998 (Suppl) 39 S12. 

Hou, J.-M., Boichenko, V.A., Diner, B.A., Mauzerall, D. (2001) Thermodynamics of electron transfer in oxygenic photosynthetic reaction centers Volume change, enthalpy, and entropy of electron transfer reactions in manganese-depleted photosystem II core complexes, Biochemistry 40(24), 7117-7125. 

E. P. Morris, B. Hankamer, D. Zheleva, G. Friso, and J. Barber. 1997. The three-dimensional structure of a photosystem II core complex determined by electron crystallography Structure 5 837-849. (PubMed)... 

An explanation of the peculiar features of the PSII and PSI antenna configuration in the Chi b-less mutant may be provided upon consideration of the role of Chi b in these complexes. This pigment is associated exclusively with the LHC proteins of the two photosystems. Since the core complex of PSII contains only about 37 Chi a molecules [Glick and Melis 1988], it follows that the remaining 56 Chi a molecules in PSII of the Chi Mess mutant must be associated with LHC-II proteins. Based on the assumption of 12 Chi molecules per Lhcb protein in C. reinhardtii [Thomber et al. 1988, Morrissey et al. 1989, Bassi and Wollman 1991, Harrison and Melis 1992], we estimated that 4-5 LHC-II proteins are assembled and functionally associated with PSII. 

Attempts to prepare pure reaction-center complexes from green sulfur bacteria have proven quite difficult in the past, and usually resulted in severely diminishing the photochemical activity of the preparation. However, the new preparative procedure of Francke et al has yielded RC-complexes that are photochemically active and reasonably pure. They resemble the core complex of photosystem 1, but only have 16 BChls a and 4 molecules of the Chl-a isomer, as subsequently determined by Griesbeck, Hager-Braun, Rogl and Hauska ° for the P840-reaction center from Chlorobium tepidum. 

Fig. 2 (C) shows a model representing the thylakoid membrane of a cyanobacterium or a red alga, consisting of photosystems I and II interconnected by the cytochrome- /complex, and the ATP synthase, CFo CFi. The phycobilisomes are seen as attached to the stromal surface at the PS-II reaction-center core complex.

The [D1-161(Y->F)] mutantcellsneithergrowphotosyntheticallynorevolveoxygen,butcansynthesize photosystem II and generate the Yo-radical (SIIJ upon illumination. The core complexes prepared from either wild or mutant cells contain one reaction center per -40-50 Chi molecules. The work of Debus et and Metz et showed that fluorescence-yield changes in the mutant to be consistent with a disruption of forward electron transport on the oxidizing side of P680 as a result of the lesion created at the tyrosine site by the [Dl-161(Y->F)]mutation. 

Fig. 1. (A) Fractionation ofthe native PS-1 complex, PSI-200, into the core complex, CC I (PSI-100) and the peripheral light-harvesting complex, LHC I. (B) shows more detailed composition of PSI-200 and its subtractions. Data in (B) taken from Malkin (1987) Photosystem /. In J Barber (ed) The Light Reactions. Elsevier, p 507.

Photosystems-I thylakoids of higher plants and cyanobacteria are quite different from the bacterial system in that, for instance, besides having peripheral chlorophyll-protein complexes as antenna, there are also chlorophyll molecules functioning as the so-called core antenna complex in the reaction-center itself. A PS-1 core complex containing core antenna chlorophyll molecules was actually obtained as early... 

Fig. 7. Model for the native photosystem-l complex (PSI-200) constructed from the reaction-center core (CC I) and two copies of each ofthe four light-harvesting chlorophyll-protein complexes. Figure adapted from Boekema, Wynn and Malkin (1990) The structure of spinach photosystem I studied by eiectron microscopy. Biochim Biophys Acta 1017 55.

The Iron-Sulfur Center FeS-X of Photosystem I, the Photosystem-I Core Complex, and Interaction of the FeS-X Domain with FeS-A/FeS-B... 

Fig. 4. (A) Top light-minus-dark EPR spectrum of TSF-I particles poised at -625 mV and 9 K in the g=1.78 region ([FeS-X -FeS-X] spectrum) middle and bottom kinetics of flash-induced EPR-signal at g=1.78 on two different time scales. (B) Kinetics of the dark decay of the of the EPR signal of FeS-X" at g=1.79 (top) and of P700 at g=2.0026 (bottom) in an LDS-fractionated PS-1 core complex from spinach. Figure sources (A) Shuvalov, Dolan and Ke (1979) Spectral and kinetic evidence for two early electron acceptors in photosystem I. Proc Nat Acad Sci, USA 76 772 (B) Warden and Golbeck (1986) Photosystem I charge separation in the absence of centers A and B. II. ESR spectral characterization of center X and correlation with optical signal A. Biochim Bioohvs Acta 849 28.

Fig. 8. (A) Schematic representation of reconstitution of the PS-i core complex [P700 FeS-X] with PsaC (B) Light-induced absorbance change (LI-AA) at 698 nm in the PS-1 core complex and in the reconstituted complex (C) EPR spectra of the core complex, PsaC and the reconstituted complex. Panel (D) is the EPR spectrum of the native PS-1 reaction-center complex. See text for experimentai details. Figure source Golbeck, Mehari, Parrett and Ikegami (1988) Reconstitution of the photosystem i compiex fmm the P700 and Fx-containing reaction center core protein and the FfjF polypeptide. FEBS Lett 240 10, 11, 12.

Fig. 9. (A) EPR spectra of the PS-1 core complex [P700 FeS-X] (a), the complex in which FeS-X was removed (b), and the reconstituted complex (c) (B) Flash-induced absorbance changes monitored at 698 nm for samples (a), (b) and (c) in (A) and their decay kinetics. Figure source Parrett, Mehari and Golbeck (1990) Resolution and reconstitution of the cyanobacteria photosystem I complex. Biochim Biophys Acta 1015 348, 349...

In addition to the work on the nature and reactivity of FeS-X in photosystem I and the isolation ofthe PS-I core complex as described above, the chemical composition of FeS-X was also investigated in several laboratories in tbe 1980s. In 1984, Lagoutte, Setifand Duranton ", using in vivo-labeling and... 

Fig. 10. Mdssbauer spectra of reduced (left panels) and oxidized (right panels) PS-I core complex at 80 K (top panels) and 4.2 K (bottom panels), The lower spectrum in each of the left panels was corrected for the unreduced component. The table at top right lists the experimentally determined isomer-shift (IS) and quadrupole-splitting (QS) parameters for oxidized and reduced core complexes at 77 K lower table lists isomer-shift values reported in the literature for other [4Fe 4S] and [2Fe 2S] clusters. Data source Petrouleas, Brand, Parrett and Golbeck (1989) A Mossbauer analysis of the low-potential iron-sulfur center in photosystem I Spectroscopic evidence that Fx is a [4Fe-4S] cluster. Biochemistry 28 8982.

Fig. 14. (A) Absorbance-difference spectra, plotted as differential molar absorptivity, Ae, for FeS-X and P430 from flash-induced transients with intact PS-I complex P700 Ao Ai FeS-X [FeS-A/B] and the PS-I core complex P700 Ao Ai FeS-X] (B) Kinetic traces of flash-induced absorbance changes at 430 and 416 nm for the intact PS-I complex (C) Kinetic traces of flash-induced absorbance changes at 453 nm for the intact PS-I complex (top trace) and the PS-I core complex (bottom trace). Note the 10-fold difference in AA scale between (B) and (C). Figure source Franke, Ciesla and Warden (1995) Kinetics of PsaC reduction in photosystem I. In P Mathis (ed) Photosynthesis from Light to Biosphere (Proc IX Intern Congr Photosynthesis). Vol. II 77. Kluwer.

JH Golbeck, T Meharl, K Parrett and I Ikegami (1988) Reconstitution of the photosystem 1 complex from the P700 and Fx-containing reaction center core protein and the F /Fg polypeptide. FEBS Lett 240 9-14... 

Fig. 2. (A) Flash-induced AA in the SDS-fractionated PS-1 core complex (CPI) at 5 K [ with and o without DCIP] (B) Flash-induced AA in TSF-I particles containing dithionite and neutral red at pH 10 and frozen while being illuminated (C) left AA induced by 300-ns, dye laser flashes [710 nm for the blue and green region 590 nm for the red region] insets show individual AA transients at 696 and 480 nm (C) right The difference between the difference spectrum in the left panel and that of P700. (D) Plot of the rate constant vs. reciprocal temperature. Figure source (A) Mathis, Sauer and Remy (1978) Rapidly reversible flash-induced electron transfer on a P-700 chlorophyll-protein complex isolated with SDS. FEBS Lett 88 277 (8) Sauer, Mathis, Acker and van Best (1979) Absorption changes of P-700 reversible in milliseconds at low temperature in Triion-solubilized photosystem I particles. Biochim Biophys Acta 545 469 (C and D) Shuvalov, Dolan and Ke (1979) Spectral and kinetic evidence for two eariy electron acceptors in phoiosystem I. Proc Nat Acad Sci, USA 76 771,773.

Fig. 11. (A) Decay-associated difference spectra (DADS) of the 3-, 28-ps and the non-decaying components of Synechocystis PS-I core complex in the 380-500 nm region under reducing conditions and at room temperature. (B) The absorbance-difference spectrum AA [Ao"-Ao] (solid line) the same spectrum [see Fig. 9 (A), left panel] obtained from spinach is included for comparison. Figure source Mi, Lin and Blankenship (1999) Picosecond transient absorption spectroscopy in the blue spectral region of photosystem I. Biochemistry 38 15234. 15235.

Hg. 6. Laser flash-induced absorbance changes (AA) observed in a core complex at 819 nm (A) and 380 nm (B) at 298 K aA at 819 nm presented on three time scales with parameters derived by computer cun/e fitting AA at 380 nm without and with ferricyanide (C) absorbance difference spectra in the UV/vis region constructed from the 10-//s- and 100-ps decay phases. Figure source Brettel and Golbeck (1995) Spectral and kinetic characterization of electron acceptor A, in a photosystem I core devoid of iron-sulfur centers Fx, Fb and Fa- Photosynthesis Res 45 185,187. 

Fig. 7. Picosecond kinetics of flash-induced absorbance changes at 432 and 380-390 nm in PS-1 core complex [PTOO-AqA,] isolated from Synechocystis sp. PCC 6803. Figure source Brettel and Vos (1998) Spectroscopic resolution of the picosecond reduction kineticsofthe secondary electron acceptor in photosystem I. FEBS Lett 447 316.

Fig. 11. A) Flash-induced absorbance changes in the PS-I complex prepared from the cyanobacterium Synechocystis and the PS-I core compiex after urea treatment to remove PsaC (FeS-A/B), PsaD, and PsaE, at 384 nm (ieft) and 435 nm (right) (B) Flash-induced absorbance change at 380 nm in a simiiar Synechocystis PS-I complex under conditions similar to those used to obtain the upper left trace in (A) (C) Flash-induced photovoltage change in the same PS-I complex used in (B). Figure source (A) LOneberg, Fromme, Jekow and Schlodder (1994) Spectroscopic characterization of PS I core complexes from thermophilic Synechococcus sp. Identical reoxidation kinetics of Af before and after removal of the iron-sulfur-clusters Ff and F. FEBS Lett 338 200.201 (B) and (C) LeibI, T oupance and Breton (1996) Photoelectric characterization of forward electron transfer to iron-sulfur centers in photosystem I. Biochemistry 34 10239,10240.

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