FMO protein

The Fenna-Matthews-Olson (FMO) protein is an unusual, water-soluble chlorophyll protein found only in green sulfur bacteria. [18] It is believed to be located between the chlorosome and the cytoplasmatic membrane and functions as an excitation transfer link between the chlorosome and the reaction center. Each subunit contains 7 BChl a molecules embedded in a primarily /3 sheet structured protein. The protein has a trimeric quaternary structure, with a three-fold axis of symmetry in the center of the complex. [55] The green nonsulfur bacteria do not contain the FMO protein. In these organisms the chlorosome transfers energy directly to the integral membrane core antenna B808-865, and then to the reaction center. 

Another important experimental consideration regarding FMO enzymes is that, in contrast to CYP enzymes, they cannot be inhibited by polyclonal antibodies, even when these antibodies recognize the FMO protein on a Western immunoblot. 

Figure 7 Rogue s gallery of structures of peripheral anteima complexes. As labelled these include Chlorosomes from green sulfur bacteria, fused antenna domains of the Photosystem I core, the CP43 and CP47 proteins of Photosystem II, the Fenna-Matthew-Olson (FMO) protein associated with chlorosomes, LHI proteins surrounding a purple bacterial photo synthetic core, the peridinin-chlorophyll a protein of dinoflagellate algae, the LHCI and LHCII proteins found in plants and many algae, and the LHII protein complex that is associated with LHI in purple bacteria...

Another antenna complex where high-resolution structural information is available is the bacteriochlorophyll a binding protein (also known as the Fenna-Matthews-Olson or FMO protein) from green sulfur bacteria. This complex serves as the bridge between the peripheral chlorosome complex and the membrane-bound reaction center complexes. In this... 

Chlorosome BChl a-protein trimers ("FMO" protein) Baseplate... 

Typically, each chlorosome contains as many as 10,000 BChl-c molecules, some carotenoids and several hundred BChl-a molecules serving as the sub-antenna in the baseplate and as core antennae in the cytoplasm. Chlorosomes and the BChl a-protein, or the FMO protein, are discussed in Chapter 8. 

The Baoteriochlorophyll a-Protein Complex (the FMO Protein ) in the Reaotion Center-Antenna Complex of Chlorobiaoeae.155... 

JM Olson (1994) Reminiscence about Chioropseudomonas ethyiicum and the FMO-protein.Pho osyr hes s Res 41 3-5... 

In 1987, Vasmel, Swarthoff, Kramer and Amesz" attempted to prepare a more enriched RC core by treating the RCPP-complex with lithium dodecyl sulfate to remove the FMO-protein. Although the FMO-protein was extracted, the resulting RC core was photochemically inactive. 

The molecular masses ofthe 3-FMO/RC-core, the 1-FMO/RC-core, and the RC core are 600, 330-350 and 150-250 kDa, respectively. All three complexes contain the 65-kDaRC protein ipscA) and the iron-sulfur protein FeS-A/B ipscB). Only the RC core complex lacks the 42-kDa FMO protein. All three complexes are photochemically active at both room and cryogenic temperatures. The photochemical activity of the primary electron donor P840 can be estimated by comparing the light-induced absorbance changes at 840 nm to the absorbance at 810 nm as shown in Fig. 3. 

C Griesbeck, C Flager-Braun, FI RogI and G Flauska (1998) Quantitation of P840 reaction center preparations from Chlorobium tepidum Chlorophylls and FMO-protein. Biochim Biophys Acta 1365 285-293... 

Camara-Artigas A, Blankenship RE, and Allen JP. The structure of the FMO protein from Chlorobium tepidum at 2.2 angstrom resolution. 

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