Reaction Centers from Purple Bacteria

Allen, James P.; Williams, Joann

doi:10.1002/9783527623464.ch12

Cited by 7 publications

(12 citation statements)

References 87 publications

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“…Demetalation of Chls to yield Phe pigments is essential for formation of the primary electron acceptor in photosystem(PS)-II type RCs [27], although the details of the formation are still unclear. In this study, a decrease in the ratio of BPhes-a esterified with GG, DHGG and THGG over the total BPhe-a content was observed, compared to the corresponding BChls-a, especially for the most rigid geranylgeranylated BPhe-a; BPhe-a with GG was detected at most 10% of the total BPhe-a in Rsp.…”

Section: Discussionmentioning

confidence: 99%

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The 17-propionate esterifying variants of bacteriochlorophyll-a and bacteriopheophytin-a in purple photosynthetic bacteria

Mizoguchi

Isaji

Harada

et al. 2015

Journal of Photochemistry and Photobiology B: Biology

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Most purple photosynthetic bacteria contain bacteriochlorophyll(BChl)-a (a magnesium complex) and bacteriopheophytin(BPhe)-a (its free base) as their photoactive pigments. These pigments are composed of two parts: a cyclic tetrapyrrole as the chromophore and a long hydrocarbon-chain as the propionate-type esterifying group at the 17-position. The hydrocarbon-chain is usually an isoprenoid-type C20 phytyl (Phy) group in both the pigments. In the ester group of BChl-a, several variants such as geranylgeranyl (GG), dihydrogeranylgeranyl (DHGG) and tetrahydrogeranylgeranyl (THGG) groups were found in the final stage of BChl-a biosynthesis. On the other hand, the esterifying variants in BPhe-a have not been studied as much due to the lower levels of this pigment relative to BChl-a. The esterifying group does not affect the electronic absorption properties of such pigments in the monomeric state, but drastically alters the hydrophobicity. In this study, BChl-a and BPhe-a in the six phylogenetically distinct classes of purple bacteria were analyzed in terms of their esterifying groups in the 17-propionate residues, using high-performance liquid chromatography. Both BChls-a and BPhes-a carrying GG, DHGG and THGG in addition to the usual Phy were found for all the bacterial species studied at measurable levels. In some of the species, the ratio of BPhes-a esterified with GG, DHGG and THGG over the total BPhe-a drastically decreased in comparison with that of the corresponding BChls-a. Especially, the relative content of BPhe-a with GG largely decreased. This observation might indicate that BPhe-a as a cofactor of reaction centers was preferentially esterified with partially reduced and flexible chains (THGG and Phy) rather than less reduced and rigid ones (GG and DHGG).

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Section: Discussionmentioning

confidence: 99%

“…rubrum which does not contain peripheral LH2 is calculated to be 18:1 in the following manner. The X-ray crystallographic analyses of purple bacterial RCs revealed that the molecular numbers of BChl-a and BPhe-a were 4:2 in the single RC [27,28]. The LH1 complex of Rsp.…”

Section: Compositions Of Bchl-a and Bphe-a Variants In Purple Bacteriamentioning

confidence: 99%

The 17-propionate esterifying variants of bacteriochlorophyll-a and bacteriopheophytin-a in purple photosynthetic bacteria

Mizoguchi

Isaji

Harada

et al. 2015

Journal of Photochemistry and Photobiology B: Biology

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“…In this kind of reaction center the distance between these BChls amounts to about 3 . [457] Due to this close proximity, the (B)Chls interact strongly with each other. This causes an increased reduction potential and a large red shift of the excitation energy.…”

Section: Reaction Centers and The Special Pairmentioning

confidence: 98%

“…This causes an increased reduction potential and a large red shift of the excitation energy. [1,457] The first is essential for the charge separation function of the reaction center, but since a detailed discussion of the redox processes in photosynthesis goes beyond the scope of this Review, we will focus on the optical features, that is, the red shift, and the character of these excited states.…”

Section: Reaction Centers and The Special Pairmentioning

confidence: 99%

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

2011

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The theoretical description of the initial steps in photosynthesis has gained increasing importance over the past few years. This is caused by more and more structural data becoming available for light-harvesting complexes and reaction centers which form the basis for atomistic calculations and by the progress made in the development of first-principles methods for excited electronic states of large molecules. In this Review, we discuss the advantages and pitfalls of theoretical methods applicable to photosynthetic pigments. Besides methodological aspects of excited-state electronic-structure methods, studies on chlorophyll-type and carotenoid-like molecules are discussed. We also address the concepts of exciton coupling and excitation-energy transfer (EET) and compare the different theoretical methods for the calculation of EET coupling constants. Applications to photosynthetic light-harvesting complexes and reaction centers based on such models are also analyzed.

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“…Since the core subunits of Type 1 RC proteins are predicted to have 11 transmembrane a-helices 124, 125 , while type 2 RC are known to contain ve transmembrane helices 124,126 , we also searched for all predicted proteins harboring either 5 or 11 transmembrane domains using TMHMM . All identi ed 5-or 11-helix-containing protein-coding sequences were searched against GenBank protein nr database to identify and exclude all sequences with a predicted function.…”

Section: Methodsmentioning

confidence: 99%

Methylotrophy, alkane-degradation, and pigment production as defining features of the globally distributed yet-uncultured phylum Binatota

Murphy

Dunfield

Sheremet

et al. 2020

Preprint

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The recent leveraging of genome-resolved metagenomics has opened a treasure trove of genomes from novel uncultured microbial lineages, yet left many clades undescribed. We here present a global analysis of genomes belonging to the Binatota (UBP10), a globally distributed, yet-uncharacterized bacterial phylum. All orders in the Binatota encoded the capacity for aerobic methylotrophy using methanol, methylamine, sulfomethanes, chloromethanes, and potentially methane as substrates. Methylotrophy in the Binatota was characterized by order-specific substrate degradation preferences, as well as extensive metabolic versatility, i.e. the utilization of diverse sets of genes, pathways and combinations to achieve a specific metabolic goal. The genomes also encoded an arsenal of alkane hydroxylases and monooxygenases, potentially enabling growth on a wide range of alkanes and fatty acids. Pigmentation is inferred from a complete pathway for carotenoids (lycopene, β and γ carotenes, xanthins, chlorobactenes, and spheroidenes) production. Further, the majority of genes involved in bacteriochlorophyll a, c, and d biosynthesis were identified; although absence of key genes and failure to identify a photosynthetic reaction center precludes proposing phototrophic capacities. Analysis of 16S rRNA databases showed Binatota’s preferences to terrestrial and freshwater ecosystems, hydrocarbon-rich habitats, and sponges supporting their suggested potential role in mitigating methanol and methane emissions, alkanes degradation, and nutritional symbiosis with sponges. Our results expand the lists of methylotrophic, aerobic alkane degrading, and pigment-producing lineages. We also highlight the consistent encountering of incomplete biosynthetic pathways and gene shrapnel in microbial genomes, a phenomenon necessitating careful assessment when assigning putative functions based on a set-threshold of pathway completion.

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Reaction Centers from Purple Bacteria

Cited by 7 publications

References 87 publications

The 17-propionate esterifying variants of bacteriochlorophyll-a and bacteriopheophytin-a in purple photosynthetic bacteria

The 17-propionate esterifying variants of bacteriochlorophyll-a and bacteriopheophytin-a in purple photosynthetic bacteria

Quantum Chemical Description of Absorption Properties and Excited‐State Processes in Photosynthetic Systems

Methylotrophy, alkane-degradation, and pigment production as defining features of the globally distributed yet-uncultured phylum Binatota

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