Photosynthetic pigment-protein complexes

The carotenoids are located in photosynthetic pigment-protein complexes (PPCs) in the thylakoid membranes (Young, 1993), with minor amounts in the chloroplast envelope (Joyard et al, 1991) and the envelope of amyloplasts (Fishwick and Wright, 1980). In all plastid envelope membranes, violaxanthin is the major carotenoid. Carotenes are also found in plastoglobuli (Lichtenthaler and Peveling, 1966). 

Renger, T., May, V. and Kuhn, O. (2001). Ultrafast excitation energy dynamics in photosynthetic pigment protein complexes. Phys. Rep. 343, 137-254. 

Cover concept by eStudio Calamar Steinen using a background picture from The Protein Databank (1 Kzu). Courtesy of Dr. Antoine M. van Oijen, Department of Molecular Physics, Huygens Laboratory, Leiden University, The Netherlands. Reprinted with permission from Science 285 (1999) 400-402 ("Unraveling the Electronic Structure of Individual Photosynthetic Pigment-Protein Complexes", by A. M. van Oijen et al.) Copyright 1999, American Association for the Advancement of Science. 

Historically the first X-ray structure [43-45] to undergo exciton analysis was that of the water-soluble BChl a-protein from the green photosynthetic bacterium Prosthecochloris aestuarii. The analysis [16] raised questions, and controversies, that remain unresolved after a decade. It is reviewed again here to emphasize these difficulties, to correct some misconceptions in the literature [4,46,47] regarding possible sources of the difficulties, and to discuss more recent developments. Exciton analysis of photosynthetic pigment-protein complexes is iipt likely to become a truly useful procedure until it produces results that agree with all relevant spectra of this particular complex. 

The subject of energy transfer in phycobilisomes and their sub-structures already has a large literature (see Ref. 65 for a review), mostly beyond the scope of this chapter. However, two of these sub-structures - trimeric C-phycocyanin from the thermophilic cyanobacterium Mastigocladus laminosus and hexameric C-phycocyanin from the cyanobacterium Agmenellum quadruplicatum-have very recently become respectively the third and fourth photosynthetic pigment-protein complexes for which structural models based on single-crystal X-ray diffraction near atomic resolution are now available (Refs. 66,67 and Chapter 11). Since these are presently the only such complexes, in addition to the two already discussed (Sections 5 and 6), it seems appropriate to conclude this review of exciton effects with some brief remarks on these C-phycocyanin structures. 

The Influence of Symmetry on the Electronic Structure of the Photosynthetic Pigment-Protein Complexes from Purple Bacteria... 

A.M. van Oijen, M. Ketelaars, J. Kohler, T.J. Aartsma, J. Schmidt, Unraveling the electronic structure of individual photosynthetic pigment-protein complexes. Science 285, 400-402 (1999)... 

J Breton and E Nabedryk (1984) Transmembrane orientation ofa-helices and the organization of chlorophyll in photosynthetic pigment protein complexes. FEBS Lett 176 355-359... 

In Methylobacterium radiotolerans (previously, Pseudomonas radiora), spirilloxanthin is the dominant component in the RC-LHI complex (Saitoh et al., 1995), while carotenoic acids are found in the outer membranes accompanied by no BChls and have nophotosynthetic functions (S. Saitoh, personal communication). Two species of Methylobacterium have also similar carotenoic acids with M radiotolerans, and two species of the forth group described above have polar carotenoids, diapocarotenoic acid derivatives. These highly polar carotenoids in the third, the forth and the fifth groups may be nonphotosynthetic carotenoids, which are not bound to the photosynthetic pigment-protein complexes (Shimada, 1995). Although their functions are not known, there is the possibility that they protect the photosynthetic apparatus from the outside aerobic conditions. 

The accumulation ofzeaxanthin in the thylakoid membranes in effect of the de novo synthesis of pigment as aresponse to the prolonged illumination with strong light (Schindler and Lichtenthaler, 1994 Schafer et al., 1994) was not accompanied by stoichiometric concentration inaease of the photosynthetic pigment-protein complexes or the... 

Our polypeptides represent the upper limit of molecular fields, which can be bound in photosynthetic pigment-protein complexes. The experimental results still confirm the applicability of the perturbational theory for induced energy changes. We can therefore conclude that this theoretical approach can be safely used for the studies of related problems in vivo. ... 

In photosynthetically active chloroplasts, the carotenoids are found as part of photosynthetic pigment-protein complexes (PPCs) in the thylakoid membranes. The core complex, CCI, contains one /3-carotene molecule per 40 chlorophyll a, whereas the light-harvesting complex LHCI is associated with lutein, violaxanthin, and neoxanthin. /3-Carotene is also located in CCII, ° while LHCII contains xanthophylls." The separation, identification, and nomenclature of the PPCs has been discussed in detail in several recent reviews. ... 

Yurkov, V.V, Krieger, S., Stackebrandt E., and Beatty, J.T. (1999) Citromicrobium bathyomarinum, a novel aerobic bacterium isolated from deep-sea hydrothermal vent plume waters that contains photosynthetic pigment-protein complexes. J. Bacteriol., 181, 4517-4525. 

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