Conjugation-Length Dependence of the T<sub>1</sub> Lifetimes of Carotenoids Free in Solution and Incorporated into the LH2, LH1, RC, and RC-LH1 Complexes:  Possible Mechanisms of Triplet-Energy Dissipation

Kakitani, Yoshinori; Akahane, Junji; Ishii, Hiroki; Sogabe, Hiroshi; Nagae, Haruki; Koyama, Yasushi

doi:10.1021/bi062237z

Cited by 36 publications

(46 citation statements)

References 55 publications

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“…Therefore, carotenoids with shorter triplet lifetimes will also fulfill this protective function with the same yield. The dependence similarly follows a linear relationship in this representation as was found for triplet states of selected carotenoids in organic solutions and LH preparations (Kakitani et al 2007a), or for singlet excited states in LH2 preparation . …”

Section: Triplet (Dark and Light) Lifetimes Of The Antenna Carotenoidssupporting

confidence: 62%

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Photoprotection in intact cells of photosynthetic bacteria: quenching of bacteriochlorophyll fluorescence by carotenoid triplets

Sipka

Maróti

2017

Photosynth Res

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Upon high light excitation in photosynthetic bacteria various triplet states of pigments can accumulate leading to harmful effects. Here, the generation and lifetime of flash-induced carotenoid triplets ( 3 Car) have been studied by observation of the quenching of bacteriochlorophyll (BChl) fluorescence in different strains of photosynthetic bacteria including Rvx. gelatinosus (anaerobic and semianaerobic), Rsp. rubrum, Thio. roseopersicina, Rba. sphaeroides 2.4.1 and carotenoid and cytochrome deficient mutants Rba. sphaeroides Ga, R-26 and cycA, respectively. The following results were obtained: 1) 3 Car quenching is observed during and not exclusively after the photochemical rise of the fluorescence yield of BChl indicating that the charge separation in the reaction center (RC) and the carotenoid triplet formation are not consecutive but parallel processes. 2) The photo-protective function of 3 Car is not limited to the RC only and can be described by a model in which the carotenoids are distributed in the lake of the BChl pigments.3) The observed lifetime of 3 Car in intact cells is the weighted average of the lifetimes of the carotenoids with various numbers of conjugated double bonds in the bacterial strain. 4) The lifetime of 3 Car measured in the light is significantly shorter (1-2 μs) than that measured in the dark (2-10 μs). The difference reveals the importance of the dynamics of 3 Car before relaxation. The results will be discussed not only in terms of energy levels of the 3 Car but also in terms of the kinetics of transitions among different sublevels in the excited triplet state of the carotenoid.

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Section: Triplet (Dark and Light) Lifetimes Of The Antenna Carotenoidssupporting

confidence: 62%

“…Additionally, even slight differences were reported in various reconstituted LH1 and LH2 complexes and LH1 and RC components of the RC-LH1 complex (Kakitani et al 2007a). Regarding Eq.…”

Section: Triplet Decay Rates Of Carotenoids Of Different Conjugation mentioning

confidence: 99%

Photoprotection in intact cells of photosynthetic bacteria: quenching of bacteriochlorophyll fluorescence by carotenoid triplets

Sipka

Maróti

2017

Photosynth Res

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“…After a certain time, a small portion of the population is able to tolerate the toxicity so to commence cell growth, thereby lowering the pO 2 and alleviating growth inhibition. Presumably, the hydroxylated/methoxylated carotenoids (e.g., spx) lead to less structural strain than the nonhydroxylated/nonmethoxylated ones (e.g., lycopene), which explains the relative efficiencies of the in vitro reconstitution experiments (11,25). We have also observed long lag phases in other nonrelated R. rubrum mutants where the lesion causes the LH1 complex to be abnormally sensitive to oxidative stress (C. Autenrieth and R. Ghosh, unpublished data).…”

Section: Discussionmentioning

confidence: 68%

High-Level Production of the Industrial Product Lycopene by the Photosynthetic Bacterium Rhodospirillum rubrum

Wang

Grammel

Abou-Aisha

et al. 2012

Appl Environ Microbiol

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bThe biosynthesis of the major carotenoid spirilloxanthin by the purple nonsulfur bacterium Rhodospirillum rubrum is thought to occur via a linear pathway proceeding through phytoene and, later, lycopene as intermediates. This assumption is based solely on early chemical evidence (B. H. Davies, Biochem. J. 116:93-99, 1970). In most purple bacteria, the desaturation of phytoene, catalyzed by the enzyme phytoene desaturase (CrtI), leads to neurosporene, involving only three dehydrogenation steps and not four as in the case of lycopene. We show here that the chromosomal insertion of a kanamycin resistance cassette into the crtCcrtD region of the partial carotenoid gene cluster, whose gene products are responsible for the downstream processing of lycopene, leads to the accumulation of the latter as the major carotenoid. We provide spectroscopic and biochemical evidence that in vivo, lycopene is incorporated into the light-harvesting complex 1 as efficiently as the methoxylated carotenoids spirilloxanthin (in the wild type) and 3,4,3=,4=-tetrahydrospirilloxanthin (in a crtD mutant), both under semiaerobic, chemoheterotrophic, and photosynthetic, anaerobic conditions. Quantitative growth experiments conducted in dark, semiaerobic conditions, using a growth medium for high cell density and high intracellular membrane levels, which are suitable for the conventional industrial production in the absence of light, yielded lycopene at up to 2 mg/g (dry weight) of cells or up to 15 mg/liter of culture. These values are comparable to those of many previously described Escherichia coli strains engineered for lycopene production. This study provides the first genetic proof that the R. rubrum CrtI produces lycopene exclusively as an end product.

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“…In RC-LH1 complexes that contain spirilloxanthin as carotenoids the subsequent decay of the carotenoid triplet state occurs with a time constant between 1.6 and 2.9 μs. 72,73 Singlet−triplet annihilation (STA) becomes possible if a LH1 ring that still carries a triplet state (cross) gets excited again to the 1 B875* state (ellipse). This situation is depicted by a circle with both a cross and an ellipse and will be referred to as |4 LH ⟩ = | 1 B875*, 3 Car*⟩, Figure 6, blue sphere.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

The Open, the Closed, and the Empty: Time-Resolved Fluorescence Spectroscopy and Computational Analysis of RC-LH1 Complexes from Rhodopseudomonas palustris

et al. 2015

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ABSTRACT:We studied the time-resolved fluorescence of isolated RC-LH1 complexes from Rhodopseudomonas palustris as a function of the photon fluence and the repetition rate of the excitation laser. Both parameters were varied systematically over 3 orders of magnitude. On the basis of a microstate description we developed a quantitative model for RC-LH1 and obtained very good agreement between experiments and elaborate simulations based on a global master equation approach. The model allows us to predict the relative population of RC-LH1 complexes with the special pair in the neutral state or in the oxidized state P + and those complexes that lack a reaction center. ■ INTRODUCTIONPhotosynthetic purple bacteria have evolved a wonderful modular principle for the light-harvesting (LH) apparatus that captures the solar radiation. These modules consist of pairs of hydrophobic, low molecular weight polypeptides that noncovalently bind a small number of bacteriochlorophyll (Bchl a) and carotenoid (Car) molecules and that self-assemble to produce the native pigment−protein complexes. 1−6 Most purple bacteria have two main types of complexes, the core complex, RC-LH1, and the peripheral complex, LH2. In the photosynthetic membrane the LH2 complexes are arranged in a two-dimensional network around the perimeter of the RC-LH1 complexes and the light energy absorbed by LH2 is transferred via LH1 to the reaction center (RC) where it is used to separate charge across the membrane. 7 For many years, high-resolution structural information has been available for the RC, 8−11 and the peripheral light-harvesting complexes 1−3 for a couple of species, whereas the first higher-resolution X-ray structure for a RC-LH1 complex has been determined only recently. 6 The current view is that there are at least two distinct classes of RC-LH1 complexes: Those that are monomeric, i.e., consisting of one RC surrounded by one LH1 complex, and those that are dimeric. 12,13 For RC-LH1 from Rps. palustris exists a lowresolution X-ray structure. 4 Accordingly, the RC is enclosed by an overall elliptically shaped LH1 consisting of 15 αβ-subunits that feature a gap, which is also consistent with data from optical single-molecule experiments. 14,15 Each subunit accommodates two light harvesting BChl a molecules giving rise to an absorption band at 875 nm. The reaction center complex accommodates a BChl a dimer (special pair, primary donor, P), two accessory BChl a molecules (B A , B B ), two bacteriopheophytin a (BPheo a) molecules (H A , H B ), and two ubiquinones (Q A , Q B ) bound to two protein subunits denoted L and M. The cofactors are arranged in two nearly identical branches, called A and B, which share the primary donor, P. 9,11,16,17 In particular the RC from Rhodobacter (Rb.) sphaeroides has served as a cornerstone for elucidating structure−function relationships employing a large variety of spin resonance 18−23 and optical spectroscopies. 24−31 From these studies it is well established that in the RC the absorbed photon-energy is used to dri...

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Conjugation-Length Dependence of the T₁ Lifetimes of Carotenoids Free in Solution and Incorporated into the LH2, LH1, RC, and RC-LH1 Complexes: Possible Mechanisms of Triplet-Energy Dissipation

Cited by 36 publications

References 55 publications

Photoprotection in intact cells of photosynthetic bacteria: quenching of bacteriochlorophyll fluorescence by carotenoid triplets

Photoprotection in intact cells of photosynthetic bacteria: quenching of bacteriochlorophyll fluorescence by carotenoid triplets

High-Level Production of the Industrial Product Lycopene by the Photosynthetic Bacterium Rhodospirillum rubrum

The Open, the Closed, and the Empty: Time-Resolved Fluorescence Spectroscopy and Computational Analysis of RC-LH1 Complexes from Rhodopseudomonas palustris

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Conjugation-Length Dependence of the T1 Lifetimes of Carotenoids Free in Solution and Incorporated into the LH2, LH1, RC, and RC-LH1 Complexes: Possible Mechanisms of Triplet-Energy Dissipation

Cited by 36 publications

References 55 publications

Photoprotection in intact cells of photosynthetic bacteria: quenching of bacteriochlorophyll fluorescence by carotenoid triplets

Photoprotection in intact cells of photosynthetic bacteria: quenching of bacteriochlorophyll fluorescence by carotenoid triplets

High-Level Production of the Industrial Product Lycopene by the Photosynthetic Bacterium Rhodospirillum rubrum

The Open, the Closed, and the Empty: Time-Resolved Fluorescence Spectroscopy and Computational Analysis of RC-LH1 Complexes from Rhodopseudomonas palustris

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Conjugation-Length Dependence of the T₁ Lifetimes of Carotenoids Free in Solution and Incorporated into the LH2, LH1, RC, and RC-LH1 Complexes: Possible Mechanisms of Triplet-Energy Dissipation