Photosynthetic bacteria crystal structure

McDermott, G., et al. Crystal structure of an integral membrane light-barvesting complex from photosynthetic bacteria. Nature 374 517-521, 1995. 

Very few integral membrane proteins have been crystallized. The reaction-center proteins purified from membranes of photosynthetic bacteria are a notable exception. These proteins were discussed in chapter 15. Before their crystal structures were elucidated, analysis of hydropathy plots suggested that each of the two main protein subunits is folded into five transmembrane a helices, and one such helix was predicted to occur in another subunit. The crystal structures provided a beautiful confirmation of these predictions (see fig. 15.11a). Successful crystallization of the reaction-center proteins was achieved by including small,... 

Several crystal structures of [NiFe] hydrogenases have been determined from sulfate-reducing and photosynthetic bacteria [8, 84, 85], and recently also from oxygen-tolerant species [9, 10]. Two structures from the subclass [NiFeSe] hydrogenase are known [86-88] and from two [FeFe] hydrogenases [8, 89, 90],... 

Mcdermott, G., Prince, S.M., Freer, A.A., Hawthornthwaite-Lawless, A.M., Papiz, M.Z., Cogdell, R.J., and Isaacs, N.W. (1995) Crystal structure of an integral membrane light-harvesting complex from photosynthetic bacteria. Nature, 374, 517. 

G. McDermott, S.M. Prince, A.A. Freer, A.M. Hawthornthwaite-Lawless, M.Z. Pa-piz, R.J. Cogdell, N.W. Isaacs, Crystal-Structure of an Integral Membrane Light-Harvesting Complex from Photosynthetic Bacteria , Nature, 374,517 (1995)... 

These observations led to the prediction that accessory carotenoid pigments would be found in van der Waals contact with bacteriochlorophylls in the reaction centers of photosynthetic bacteria [58]. Indeed, the crystal structure of wild-type Rb. sphaeroides clearly shows spheroidene to be in contact with the adjacent monomer bacteriochlorophyll (Figure 1) [8]. 

Crystal Structure of the Light-Harvesting Complexes of Purple Photosynthetic Bacteria.71... 

As seen earlier in Chapter 2 on bacterial reaction centers, crystallization of the reaction-center protein of the photosynthetic h iCttn xm Rhodopseudomonas viridis by Michel in 1982 and subsequent determination ofthe three-dimensional structure ofthe reaction center by Deisenhofer, Epp, Miki, Huber and Michel in 1984 led to tremendous advances in the understanding ofthe structure-function relationship in bacterial photosynthesis. Furthermore, because of certain similarities between the photochemical behavior of the components of some photosynthetic bacteria and that of photosystem II, research in photosystem-II was greatly stimulated to its benefit by these advances. In this way, it became obvious that the ability to prepare crystals from the reaction-center complexes of photosystems I and II would be of great importance. However, it was also recognized that, compared with the bacterial reaction center, the PS-I reaction center is more complex, consisting of many more protein subunits and electron carriers, not to mention the greater number of core-antenna chlorophyll molecules. 

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,... 

Fritzsch G, Ermler U, Merckel M and Michel H (1996) Crystallization and structure of the photo synthetic reaction centres from Rhodobacter sphaeroides—wild type and mutants. In Michel-Beyerle M-E (ed) Reaction Centers of Photosynthetic Bacteria. Structure and Dynamics, pp 3-13. Springer-Verlag, Berlin... 

The solution of the crystal structure of reaction centers from purple photosynthetic bacteria (1-4) has raised a challenge Can we account for the directionality, speed and efficiency of the primary photochemical electron transfer reactions on the basis of the crystal structure ... 

The acceptor side of the PS II reaction center is structurally and functionally homologous to the reducing side of reaction centers from a number of photosynthetic bacteria, including Rhodopseudomonas viridis. Rhodobacter sphaeroides and capsulatus. and Chloroflexus aurantiacus. The reaction center complexes of viridis and sphaeroides have been crystallized, and the three-dimensional structure of these has been determined at high resolution [3-7]. With the exception of (a) the His residues in the bacterial reaction center that serve as ligands to the Mg of the accessory bacteriochlorophylls, and (b) the Glu residue that serves as a ligand to the non-heme iron between and Q0, all of the amino acid residues that function as important... 

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