Carotenoids in Photosynthetic Bacteria

Proteobacteria (Imhoff, 1995). The functions of carotenoids in photosynthetic bacteria have been investigated in most detail in the Rhodospirillaceae (other chapters in this book). Their RC resembles that of PS 11 of green plants. Their major BChl is BChl a or b. The RC was firstly crystallized from Bla. (previously, Rhodopseudomonas) viridis, and the localization of one carotenoid, 1,2-dihydroneuro-sporene, four BChl b and two bacteriopheophytin b molecules was determined (Deisenhofer et al., 1995). A similar localization of spheroidene in the RC of Rba. sphaeroides has also been described (Yeates et al., 1988 Ermler et al., 1994). The fine crystal structure of the LH II antenna complex from Rps. acidophila strain 10050 has shown the localization of one rhodopin glucoside and three BChl a molecules per ap monomer (McDermott et al., 1995). A similar localization of lycopene in the LH II complex from Rsp. molischiamm has also described (Koepke et al,... 

Takaichi S and Shimada K (1992) Characterization of carotenoids in photosynthetic bacteria. Methods Enzymol 213 374-385... 

Angerhofer A, Aust V, Hofbauer U and WolfHC (1992) Triplet energy transfer from bacteriochlorophyll to carotenoids in photosynthetic bacteria. In Murata N (ed) Research in Photosynthesis, Vol 1, pp 129-132. Kluwer Academic Publishers, Dordrecht... 

Bartley, G.E. et al.. Molecular cloning and expression in photosynthetic bacteria of a soybean cDNA coding for phytoene desaturase, an enzyme of the carotenoid biosynthesis pathway, Proc. Natl. Acad. Sci. USA 88, 6532, 1991. 

Carotenoids are also fonnd in photosynthetic bacteria and in some fimgi [16]. Snch componnds often have qnite nniqne stmctnral featnres reflecting their biosynthetic origin. Carotenoids fonnd in insects and animals are the resnlt of their retention from materials making np the diet of the organism, althongh the componnds may have snffered minor modifications to allow of their ntilization within the organism [17]. It shonld be noted that carotenoids in marine animals are almost always fonnd as protein complexes, and it is not possible to separate these by thin-layer methods withont prior treatment to remove or denatnre the protein. 

Structures of /3-carotene, a major carotenoid in many types of plants, and spheroidene, a common carotenoid of photosynthetic bacteria. About 350 different natural carotenoids exist. These vary widely in color, depending principally on the number of conjugated double bonds. 

Cogdell, R. J., and Frank, H. A., 1987, How carotenoids function in photosynthetic bacteria. Biochim. Biophys. Acta, 895 63n79. 

A great variety of carotenoid compounds occur in photosynthetic bacteria and algae, whereas plants contain only a few carotenoids, i.e, (i-carotene (Figure 9.41), lutein, lycopene, violaxanhin, antheraxanthin, and zeaxanthin- Tomatoes, for example, are unique among plants in that they contain low levels of Ji-carotene but... 

Raman and Infrared Spectroscopy. Two reviews deal with resonance Raman spectroscopy of carotenoid-containing biomolecules and micro-organisms152 and of carotenoids and chlorophylls in photosynthetic bacteria.153 The resonance Raman excitation profile of lycopene in acetone has been determined.154 Calculations previously used for (3-carotene do not explain the lycopene data. Several papers report detailed studies of the time-resolved resonance Raman spectra of... 

Fig. 2. Natural selection of carotenoid configuration in the reaction center (RC) and light-harvesting complex (LHC) of purple photosynthetic bacteria. See text for discussion. Figure source Koyama (1991) Structure and function of carotenoids in photosynthetic systems. J Photochem Photobiol, B Biol 9 208.

Fig. 13. Schematic representation of carotenoid tripiet state Car formation in photosynthetic bacteria when forward electron transfer is biocked. See text for discussion. Figure adapted from Frank and Cogdel) (1993) The photochemistry and function of carotenoids in photosynthesis. In A Young and G Britton, (eds) Carotenoids in Photosynthesis, p 301. Chapman and Hall.

L Smith and J Ramrez (1960) Reactions of carotenoid pigments in photosynthetic bacteria. J Bbl Chem 235 219-225... 

Springer Sot Chem Phys 42 62-66 Cogdell RJ and Frank HA (1987) How Carotenoids function in photosynthetic bacteria. Biochim Biophys Acta 895 63-79 Condon EU (1926) A theory of intensity distribution in band systems. Phys Rev 28 1182-1201 Condon EU (1947) The Franck-Condon Principle and Related Topics. Am J Phys 15 365-374 Crofts AR and Yerkes CT (1994) A molecular mechanism for quenching. FEES Lett 352 265-270 de Grooth BG, van Grondelle R, Romijn JC and Pulles MPJ (1979) The mechanism of reduction of the ubiquinone pool in photosynthetic bacteria at different redox potential. Biochim Biophys Acta 503 480-490... 

Many carotenoids have trivial names. However all carotenoids have been named semisystematically based on lUPAC-IUB nomenclature (lUPAC Commission on Nomenclatme of Organic Chemistry and the lUPAC-IUB Commission on Biochemical Nomenclature, 1975 Weedon and Moss, 1995). The structure of the end groups and carbon numberings of carotenoids within photosynthetic bacteria are illustrated in Fig. 1. A list of these names and the structures of all known naturally occurring carotenoids, and references giving data for each compound... 

A small amount of lycopene is found in Rpi. globiformis (Table 3 S. Takaichi, unpublished) and in the diphenylamine-inhibited cultures of Chr. okenii (Schmidt et al, 1963). However in diphenylamine-inhibited cultures of Rpi. globiformis, lycopene was not reported (Schmidt and Liaaen-Jensen, 1973). Although small amounts of the intermediates of phytoene desaturase are usually found in photosynthetic bacteria, if the activity of the C-1,2 hydratase is high, lycopene as the substrate may not be found. Therefore, the carotenogenesis pathways of okenone and / .g.-keto carotenoids could possibly start from lycopene rather than from neurosporene (Fig. 7). Nothing is known about how the keto group is introduced under the anaerobic conditions. 

Fig. 12. Structures of some unusual carotenoids found in photosynthetic bacteria.

Frank HA and Violette CA (1989) MonomericbacteriochlorophyU is required for the triplet energy transfer between the primary donor and the carotenoid in photosynthetic bacterial reaction centers. Biochim Biophys Acta 976 222-232 Frank HA, Bolt JD, de B. Costa SM and Sauer K (1980) Electron paramagnetic resonance detection of carotenoid triplet states. J Am Chem Soc 102 4893 898 Frank HA, Machniki J and Felber M (1982a) Carotenoid triplet states in photosynthetic bacteria. Photochem Photobiol 35 713-718... 

Hayashi H, Noguchi T and Tasumi M (1989) Studies on the interrelationship among the intensity of a Raman marker band of carotenoids, polyene chain-structure, and efficiency of the energy transfer from carotenoids to bacteriochlorophyll in photosynthetic bacteria. Photochem Photobiol 49 337-343 Horton P, Ruban AV and Walters RG (1996) Regulation of light harvesting in green plants. Annu Rev Plant Physiol Mol Biol 47 655-684... 

Cohen-Bazire G and Stanier RY (1958) Inhibition of carotenoid synthesis in photosynthetic bacteria. Nature 181 250-252 Gust D (1994) Molecular wires and girders. Nature 372 133-134... 

Biosynthetic Pathways and the Distribution of Carotenoids in Photosynthetic Organisms, with chapters on Carotenoids in Photosynthesis by Govindjee, Carotenoid Synthesis and Function in Plants by Dean DellaPenna, and Carotenoids and Carotenogenesis in Anoxygenic Photosynthetic Bacteria by Shinichi Takaichi ... 

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