Photosystem II, light harvesting complex

Ruban AV, Horton P and Robert B (1995) Resonance Raman spectroscopy ofthe Photosystem II light-harvesting complexes of green plants. A comparison ofthe trimeric and aggreggated states Biochemistry 34 2333-2337... 

Keywords Photos3mthesis, photosystem II, light-harvesting complexes, reaction centre, photostasis, photoprotection, acclimation. 

Wentworth M, Ruban AV, and Horton P. Thermodynamic Investigation into the Mechanism of the Chlorophyll Fluorescence Quenching in Isolated Photosystem II Light-harvesting Complexes. J Biol Chem. 2003 278 21845-21850. 

The outermost Chi a/b binding proteins, called LHC II (light-harvesting complex associated with photosystem II). 

Chapter 12 Photosystem-ll Light-Harvesting Complexes II. C. The Carotenoid Lutein... 

LHC I - light-harvesting complex of photosystem I LHC II - light-harvesting complex of photosystem n LHCP - light-harvesting chlorophyll-protein LM-complex - complex consisting of the L- and M-subunit... 

Figure 5-19. Schematic representation of reactions occurring at the photosystems and certain electron transfer components, emphasizing the vectorial or unidirectional flows developed in the thylakoids of a chloroplast. Outwardly directed election movements occur in the two photosystems (PS I and PS II), where the election donors are on the inner side of the membrane and the election acceptors are on the outer side. Light-harvesting complexes (LHC) act as antennae for these photosystems. The plastoquinone pool (PQ) and the Cyt b(f complex occur in the membrane, whereas plastocyanin (PC) occurs on the lumen side and ferredoxin-NADP+ oxidoreductase (FNR), which catalyzes electron flow from ferredoxin (FD) to NADP+, occurs on the stromal side of the thylakoids. Protons (H+) are produced in the lumen by the oxidation of water and also are transported into the lumen accompanying electron (e ) movement along the electron transfer chain.

Photosystem II splits water (the Hill reaction). Its reaction centre absorbs maximally at 680 run, and its is found mostly on grana, associated with light-harvesting complex II. It also contains more chlorophyll-b than PSI. 

Harrison MA and Melis A. (1992). Organization and stability of polypeptides associated with the chlorophyll a-b light-harvesting complex of photosystem-II. Plant Cell Physiol. 33, 627-637. 

Thomber JP, Peter GF, Chitnis PR, Nechushtai R and Vainstein A. (1988). The light-harvesting complex of photosystem II of higher plants. In Stevens SE Jr, Bryant DA (eds), Light-energy Transduction in Photosynthesis Higher Plant and Bacterial Models, pp. 137-154 The American Society of Plant Physiologists, Rockville, Maryland. 

Fig. 12. Simple models of various photosystems (A) purple bacteria, (B) green bacteria, (C) cyanobacteria and red algae, (D) bro n algae and (E) green plants. RC=reaction center FCPA=fucoxanthin-chlorophyll-protein assembly LHC=light-harvesting complex PS ll=photosystem II PS l=photosystem I. See text for discussion.

Chlamydomonas mutants that are entirely deficient in colored carotenoids do not accumulate reaction centers or light-harvesting complexes of Photosystem I or Photosystem II (Herrin et al., 1992). The accumulation of the mRNAs does not seem to be affected, so the failure in protein accumulation must be either due to inhibition of translation or rapid degradation of the proteins that cannot be assembled in the absence of carotenoids. Chi is also synthesized but very rapidly degraded in these mutants. 

Ruban AV, Phillip D, Young AJ and Horton P (1997) Carotenoid dependent oligomerization ofthe major chlorophyll a/b light harvesting complex of Photosystem II of plants. Biochemistry 36 7855-7859... 

In other situations, more accurate estimates of carotenoid electronic energies may be required. The S (2 Ag) state ofjS-carotene (E 14,500 cm" inn-hexane) appears to lie somewhat below the S,(Qy) state of chlorophyll a (e.g., E 14,700 cm in the light-harvesting complex of Photosystem II (Kwa et al. 1992). This suggests thatthe Sj state of j3-carotene must be involved in energy transfer (Cosgrove et al., 1990 DeCoster et al., 1992 Frank and Christensen,... 

Bialek-Bylka GE, Sakano Y, MizoguchiT, ShimamuraT, Phillip D, Koyama Y and Young AJ (1998a) Central-cis isomers of lutein found in the major light-harvesting complex of Photosystem II (LHC Ilb) of higher plants. Photosynth Res 56 255-264... 

Me Dermott G, Prince SM, Freer AA, Hawthornthwaite-Lawless AM, Papiz MZ, Cogdell RJ and Isaacs NW (1995) Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria. Nature 374 517-521 Moenne-Loccoz P, Robert B and Lutz M (1990) Structure ofthe primary reactants in Photosystem II resonance Raman studies ofDlD2 particles. In Baltscheffsky M (ed) Current Research in Photosynthesis, pp 423 26, Kluwer Academic Publishers, Dordrecht,... 

Naqvi KR, Mela TB, Raju BB, Jovrofi T, Simidjiev 1 and Garab G (1987) Quenching of chlorophyll a singlets and triplets by carotenoids in light-harvesting complex of Photosystem II Comparison of aggregates with trimers. Proc Natl Acad Sci USA 84 109-112... 

Regulation of the Structure and Function of the Light Harvesting Complexes of Photosystem II by the Xanthophyll Cycle... 

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