Prosthecochloris

Anoxygenic photosynthetic bacteria. Green sulfur bacteria. Chlorobium, Prosthecochloris purple nonsulfur bacteria Rhodopseudomonas, Rhodospirillum purple sulfur bacteria Chromatium, Thiospirillum... 

Figure 23-28 (A) Model of a light-harvesting chlorosome from green photosynthetic sulfur bacteria such as Chlorobium tepidum and species of Prosthecochloris. The chlorosome is attached to the cytoplasmic membrane via a baseplate, which contains the additional antenna bacteriochlorophylls (795 BChl a) and is adjacent to the trimeric BChl protein shown in (B) and near the reaction center. After Li et al.302 and Remigy et a/.304 (B) Alpha carbon diagram of the polypeptide backbone and seven bound BChl a molecules in one subunit of the trimeric protein from the green photosynthetic bacterium Prosthecochloris. For clarity, the magnesium atoms, the chlorophyll ring substituents, and the phytyl chains, except for the first bond, are omitted. The direction of view is from the three-fold axis, which is horizontal, toward the exterior of the molecule. From Fenna and Matthews.305 See also Li et al.302...

The bacteriochlorophyll a protein from the green phot osynthetic bacterium Prosthecochloris aestuarii has been determined at 2.8 A resolution.389 It is made up of three identical subunits, tightly packed around a three-fold symmetry axis. Each subunit consists of a core of seven bacteriochlorophyll a molecules enclosed within a bag of protein. There are extensive contacts between the phytyl chains of the seven bacteriochlorophylls within each subunit. These tails form an inner hydrophobic core. The seven magnesiums appear to be five-coordinate. In five cases the fifth ligand is a histidine side-chain, in one case a protein backbone carbonyl oxygen, and in the other case a water molecule. It appears that the removal of one or more of the bacteriochlorophyll molecules would destabilize the protein. It is unlikely that the chlorophyll can be reversibly removed from the protein. 

Schmidt, K.A., Neerken, S., Permentier, H.P., Hager-Braun, C., and Amesz, J. (2000) Electron transfer in reaction center core complex from green sulfur bacteria Prosthecochloris aestuarii and Chlorobium tepidum, Biochemistry 39, 7212-7220. 

Green sulfur bacteria Ancalochloris Chlorobium Chloroherpeton Pelodictyon Prosthecochloris Unicellular rods, spheres, vibrios... 

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. 

DETronrud, MF Schmid and BW Mathews (1986) Structure and x-ray amino acid sequence of a bacteriochlo-rophyll a protein from Prosthecochloris aestuarii refined at 1.9 resolution. J Mol Biol 188 443-454 T Katoh, M MImuro and S Takalchl (1989) Light-harvesting particles Isolated from a brown alga, DIctyota dichotoma. A supramolecular assembly of fucoxanthin-chlorophyll-protein complexes. Biochim Biophys Acta 976 233-240... 

Fig. 3. Top row absorption spectra of the 3-FMO/RC-core (A), 1-FMO/RC-core (B) and RC-core (C) complexes. The table lists various spectroscopic properties, chemical compositions, and photochemical activities. Spectra and data from Francke, Permentier, Franken, Neerken and Amesz (1997) Isolation and properties of photochemically active reaction center complexes from the green sulfur bacterium Prosthecochloris aestuarii. Biochemistry 36 14169.

Fig. 4. Light-induced absorbance changes (A) open symbols/solid line for Complex I" solid symbols/dashed line for the PP (ghotosystem-gigment) complex normalized to equal absorbance at 810 nm. (B) both traces for the RCPP (reaction center gigment grotein) complex, but on different AA scales. See text for discussion. Figures from Swarthoff and Amesz (1979) Photo-chemically active pigment-protein complexes from the green photosynthetic bacterium Prosthecochloris aestuarii. Biochim Biophys Acta. 548 p. 430, 431.

Fig. 5. Kinetics of absorbance changes in Complex I of Pc. aestuarii at various waveiengths induced by 532-nm puises of 16-ps duration. See text for details. Figure source Nuijs, Vasmei, Joppe, Duysens and Amesz (1985) Excited states and primary charge separation in the pigment system of the green photosynthetic bacterium Prosthecochloris aestuarii as studied by pico- second absorbance difference spectroscopy. Biochim Biophys Acta 807 30.

Fig. 6. Absorbance changes induced by 33-ps, 850-nm laser pulses in Complex 1 obtained from membranes of the green sulfur bacterium Pc. aestuarff. (A) Membrane with "closed RCs (sample containing FeCy and under background Illumination) (B) membrane with open RCs (sample containing Asc and PMS). Solid-line traces represent absorbance changes observed at the time the excitation flash was applied, and the dotted-line traces are for changes observed at 350 ps after the flash. Figure source Shuvalov, Amesz and Duysens (1986) Picosecond spectroscopy of isolated membranes of the photosynthetic green sulfur bacterium Prosthecochloris aestuarii upon selective excitation of the primary electron donor. Biochim Biophys Acta. 851 2, 3.

T Swarthoff and J Amesz (1979) Photochemically active pigment-protein complexes from the green photosynthetic bacterium Prosthecochloris aestuarii. Biochim Biophys Acta 548 427-432... 

FI Vasmel, T Swarthoff, FIJM Kramer and J Amesz (1983) Isolation and properties of a pigment protein complex associated with the reaction center of the green photosynthetic sulfur bacterium Prosthecochloris aestuarii. Biochim Biophys Acta 725 361-367... 

C Francke, FIP Permentier, EM Franken, S Neerken and J Amesz (1997) Isolation and properties of photochemically active reaction center complexes from the green sulfur bacterium Prosthecochloris aestuarii. Biochemistry 36 14167-14172... 

T Swarthoff, P Gast, AJ Floff and J Amesz (1981) An optical and ESR investigation on the acceptor side ofthe reaction center of the green photosynthetic bacterium Prosthecochloris aestuarii. FEBS Lett 130 93-98... 

P. aestuarii - Prosthecochloris aestuarii ps - picosecond, or 10" second PsaA-N - the polypeptide subunits of photosystem I (see Chapter 1, Table 1 to 6) psaA-N - genes encoding the PsaA-N polypeptide subunits of photosystem I (see Chapter 1, Table 1 to 6)... 

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