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Absorption spectra of Rhodopseudomonas sp. Rits grown under low-(3 lE s-1 m-2 , solid line), middle-(30 lE s-1 m-2 , dotted line) and high-light (200 lE s-1 m-2 , dashed line) conditions. Cells grown to stationary-growth phase were harvested and used for membrane preparations. All samples contained 30 lg of protein per ml
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Rhodopseudomonas sp. Rits is a recently isolated new species of photosynthetic bacteria and found to accumulate a significantly high amount of bacteriochlorophyll (BChl) a intermediates possessing non-, di- and tetra-hydrogenated geranylgeranyl groups at the 17-propionate as well as normal phytylated BChl a (Mizoguchi T et al. (2006) FEBS Lett 580:...
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... observe whether such alternation occurs in Rhodo- pseudomonas sp. Rits, we measured electronic absorption spectra of this bacterium grown under different light con- ditions. Figure 3 shows absorption spectra of membranes from the strain Rits grown under anaerobic low-, middle- and high-light conditions (irradiation at 3, 30 and 200 lE s -1 m -2 , respectively). The membranes under both high-and middle-light conditions exhibited similar spectra with absorption bands of 805 and 860 nm in the near- infrared region. In the membrane from low-light grown cells, a different spectrum with more intense band at 805 nm compared to that at 857 nm was measured. Such an absorption spectral change under different light condi- tions has been reported in Rps. palustris (vide supra) ( Hayashi et al. 1982;Evans et al. 1990), and thus the strain Rits and Rps. palustris have the common property of synthesizing the light-harvesting systems, LH4 as well as LH2, whose expression appears to be regulated by different light ...
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Novel peripheral light-harvesting (LH) complex designated as LL LH2 was isolated along with LH4 complex from Rhodopseudomonas palustris cells grown under low light intensity (LL). FPLC-MS/MS allowed to reveal PucABd and PucBabc apoproteins in LL LH2 complex, which is different from previously described LH4 complex containing PucABd, PucABa and PucB...
1. Introduction 2
2. Structure of the bacterial PSU 5
2.1 Organization of the bacterial PSU 5
2.2 The crystal structure of the RC 9
2.3 The crystal structures of LH-II 11
2.4 Bacteriochlorophyll pairs in LH-II and the RC 13
2.5 Models of LH-I and the LH-I-RC complex 15
2.6 Model for the PSU 17
3. Excitation transfer in the PSU 18
3.1 Electronic exc...
The structure at 100 K of integral membrane light-harvesting complex II (LH2) from Rhodopseudomonas acidophila strain 10050 has been refined to 2.0 A ˚ resolution. The electron density has been significantly improved, compared to the 2.5 A ˚ resolution map, by high resolution data, cryo-cooling and translation, libration, screw (TLS) refinement. Th...
Citations
... HPLC analysis of pigments from M3 cultures demonstrated that 10 elution fractions (H1-H10) were detected in HPLC profile ( Figure 3). Based on the absorption spectra, retention time, and reported literatures [18,19], H3, H4, H5, and H6 were identified as geranylgeranylated BChl a (BChl a GG ), dihydrogeranylgeranylated BChl a (BChl a DHGG ), tetrahydrogeranylgeranylated BChl a (BChl a THGG ), and phytylated BChl a (BChl a P ), respectively. H7-H10 elution fractions presented typical characteristic absorption of spheroidene (SE) series and were divided into three groups: spheroidenone (SO) group (H7), SE group (H8 and H9), and neurosporene (H10). ...
The effect of exogenous glycine (a precursor for the biosynthesis of bacteriochlorophyll) on the cell growth and photopigment accumulation was investigated in phototrophic growing Rhodobacter azotoformans 134K20. The growth rate and the biomass of strain 134K20 were significantly inhibited by glycine addition when ammonium sulfate or glutamate were used as nitrogen sources and acetate or succinate as carbon sources. A characteristic absorption maximum at approximately 423 nm was present in the absorption spectra of glutamate cultures while it was absent by the addition of high-concentration glycine of 15 mM. The component account for the 423 nm peak was eventually identified as magnesium protoporphyrin IX monomethyl ester, a precursor of bacteriochlorophyll a (BChl a). Comparative analysis of pigment composition revealed that the amount of BChl a precursors was significantly decreased by the addition of 15-mM glycine while the BChl a accumulation was increased. Moreover, glycine changed the carotenoid compositions and stimulated the accumulation of spheroidene. The A850 /A875 in the growth-inhibited cultures was increased, indicating an increased level of the light-harvesting complex 2 compared to the reaction center. The exogenous glycine possibly played an important regulation role in photosynthesis of purple bacteria.
... The CD in PNSB trap light in the blue-green spectral region of visible light, namely, 450− 550 nm (Kuo et al., 2012;Muzziotti et al., 2017). This characteristic allows these bacteria to absorb in a spectral range not covered by Bchls and constitutes an adaptation mechanism for the microorganism in order to survive at a huge range of light conditions (Harada et al., 2007;Niedzwiedzki et al., 2015). Additionally, Bchls and CD participate in the photoprotection mechanism by transferring energy from triple excited state of Bchla to the CD, thus avoiding the formation of deleterious reactive species (Niedzwiedzki et al., 2015;Muzziotti et al., 2017). ...
... For example, R. palustris synthesizes the LH1-RC core and LH2 under high light (HL) intensity conditions. However, at LL intensities LH2 can be substituted by LH4, which has different pigment composition (32 Bchls compared to 9 in LH2) and absorption properties (Evans et al., 2005;Harada et al., 2007). Therefore, it is important to study the changes in the ratio of Bchls and CD during bacterial growth to understand how bacteria adapt to their environment, to determine the time of pigments production, and the type of pigments that could be obtain in a process. ...
Carotenoids (CD) are biological pigments produced for commercial purposes. Therefore, it is necessary to study and determine the optimal conditions for increased CD production. There is no consensus in the literature about the conditions that increase CD production. Some authors stated that CD will be preferentially produced at low light intensities, at this adverse condition, microorganism will increase CD production as a survival response mechanism to get more energy. Other authors have mentioned that CD concentrations increase as the light intensity supplied increases, to avoid the overexposure of light and in turn photo-inhibition. Additionally, to increase the specific CD production is also necessary to increase the amount of biomass. In this work, the ammonium concentration (high (HAC) and low (LAC)) and the low light (LL) intensity effect on the CD production was evaluated. Data showed that a high CD-specific concentration of 8.8 mg/gcell was obtained by using R. palustris ATCC 17001 under HAC and LL intensity. CD production was similar at HAC and LAC, suggesting that the light intensity has a greater effect on the specific CD concentration than the nitrogen concentration. In general, the results showed a low biomass production compared to the literature, with high CD synthesis.
... Purple bacteria are capable of regulating their photosynthetic unit according to environmental factors, for instance, light intensity ( Harada et al., 2008 vesting complex 1 (LH1) is located in between the reaction center (RC) and light harvesting complex 2 (LH2), the latter being located at the periphery of the photosynthetic unit. LH1 and LH2 consist of photosynthetic pigments, i.e. carotenoids and bacteriochlorophyll a, non-covalently bound to membrane proteins. ...
The ability of Rhodopseudomonas palustris cells to rapidly acclimate to high light irradiance is an essential issue when cells are grown under sunlight. The aim of this study was to investigate the photo-acclimation process in Rhodopseudomonas palustris 42OL under different culturing conditions: (i) anaerobic (AnG), (ii) aerobic (AG), and (iii) under H2- producing (HP) conditions both at low (LL) and high light (HL) irradiances. The results obtained clearly showed that the photosynthetic unit was significantly affected by the light irradiance at which Rp. palustris 42OL was grown. The synthesis of carotenoids was affected by both illumination and culturing conditions. At LL, lycopene was the main carotenoid synthetized under all conditions tested, while at HL under HP conditions, it resulted the predominant carotenoid. Oppositely, under AnG and AG at HL, rhodovibrin was the major carotenoid detected. The increase in light intensity produced a deeper variation in light- harvesting complexes (LHC) ratio. These findings are important for understanding the ecological distribution of PNSB in natural environments, mostly characterized by high light intensities, and for its growth outdoors.
... It was previously reported that the bciC-deleted mutant of C. tepidum accumulated magnesium-free Chlide a, pheophorbide a (Pheide a) and its derivatives, and could not synthesize BChl c, indicating that BciC affected the removal of the C13 2 -methoxycarbonyl group (Liu and Bryant 2011). Similar conversion of Pheide a to pyroPheide a, which is the C13 2 -unsubstituted form of Pheide a, is observed during Chl a breakdown in plants, algae and some cyanobacteria (Schoch et al. 1981, Wahlund and Madigan 1995, Harada et al. 2008, Christ et al. 2012. Two-types of enzymes showing different activities have been identified as catalyzing the reactions. ...
A BciC enzyme is related to the removal of C132-methoxycarbonyl group in biosynthesis of bacteriochlorophylls[BChl(s)] c, d, and e functioning in green sulfur bacteria, filamentous anoxygenic phototrophs, and phototrophic acidobacteria. These photosynthetic
bacteria have the largest and the most efficient light-harvesting antenna systems, called chlorosomes, containing unique self-aggregates
of BChl c, d, or e pigments, that lack the C132-methoxycarbonyl group which disturbs chlorosomal self-aggregation. In this study, we characterized the BciC derived from
the green sulfur bacterium Chlorobaculum tepidum, and examined the in vitro enzymatic activities of its recombinant protein. The BciC-catalyzing reactions of various substrates showed that the enzyme
recognized chlorophyllide(Chlide) a and 3,8-divinyl(DV)-Chlide a as chlorin substrates to give 3-vinyl-bacteriochlorophyllide(3V-BChlide) d and DV-BChlide d, respectively. Since the BciC afforded a higher activity with Chlide a than that with DV-Chlide a and no activity with (DV-)protoChlides a (porphyrin substrates) and 3V-BChlide a (a bacteriochlorin substrate), this enzyme was effective for branching the chlorosomal pigment biosynthetic pathway at the
stage of Chlide a away from syntheses of other pigments such as BChl a and chlorophyll a. The addition of methanol to the reaction mixture did not prevent the BciC activity, and we identified this enzyme as Chlide
a demethoxycarbonylase, not methylesterase.
... Some photosynthetic purple bacteria accumulate bacteriochlorophylls-a possessing GG, DHGG, THGG groups as well as a phytyl group. 62,63 From the cultured cells of one of the above strains, each pigment was separated by HPLC and analyzed by 1 H/ 13 C NMR spectroscopy. 64 The four isolated species were confirmed and their molecular structures were identified. ...
Photosynthetically active chlorophyll molecules are biosynthesized from 5-aminolevulinic acid through protoporphyrin IX. The multi-step enzymatic transformations were well investigated, but their pathways and reaction mechanisms have not been fully elucidated in the late stages. The biosynthetic pathways of (bacterio)chlorophylls from protoporphyrin IX are here described from a chemical viewpoint, especially focusing on the reduction processes of the C=C double to C–C single bonds. The regioselective and stereoselective trans-hydrogenation is performed in the enzymatic reductions.
... [12] Strains R7 and CQV97 were grown photoheterotrophically at 28 AE 2 C on their respective medium. [12,13] LH2 were isolated according to the procedure described in ref. [14] Then, the LH2 were extensively dialyzed against 10 mmol=L Tris-HCl (pH 8.0) overnight at 4 C with several changes in buffer, and stored at 4 C before use. ...
To investigate the feasibility of using near-infrared absorption to predict stability of light-harvesting complex 2 from the purple bacteria, we compared the structural stability of light-harvesting complex 2 with different absorption properties. The spectral changes showed that light-harvesting complex 2 from Rhodobacter azotoformans (absorption maxima at 799 and 847 nm) was more susceptible to both sodium-dodecylsulfate and acid than light-harvesting complex 2 from Rhodopseudomonas palustris (absorption maxima at 803 and 857 nm). It is concluded that a relatively redshifted near-infrared absorption tends to indicate a more stable structure of light-harvesting complex 2.
... Biosynthesis of BChl and carotenoids are apparently regulated in response to environmental factors. [3] Rhodobacter(R.) sphaeroides and R. capsulatus have established AppA/PpsR, PrrB/PrrA, FnrL, RegAB and CrtJ regulator systems, which regulate the synthesis of photosynthetic pigments in response to light and oxygen signals. [4][5][6] When exposed to As, Rhodovulum sulfidophilum (CDM2) containing the biosensor plasmid, produced the yellow fluorescscence protein(phiYFP) from ArsR/Pars, [7] and Rhodopseudomonas palustris produced the carotenoidmetabolizing protein CrtIBS. ...
... The mass spectrum of the six photosynthetic pigment bands were consistent with Tetrahydrogeranylgeranyl (T1, BChl a THGG ), phytylated BChl a p (T2, BChl a p ), bacteriopheophytin (T3, Bphe), hydroxyspheroidene (T4, OH-SE), spheroidenone (T5, SO) and spheroidene (T6, SE) with a molecule ion at m/z 909.6, 911.6, 889.6, 586.9, 582 and 568, respectively (Fig. 6). [3,16,[20][21][22][23] When strain XJ-1 was exposed to different concentrations of As(III) and As(V), the pigment OH-SE was not present (Figs. 5 and 7). The pigment Bphe was not present when the cells were treated with low concentrations of As: 0.5 mM of As(V) and 0.2 mM of As(III) (Figs. 5 and 7). ...
... The photosynthetic pigments BChl a DHGG , BChl a GG , BChl a THGG , and BChl a P were consistently detected as intermediates, and were widely distributed in purple photosynthetic bacteria. [3] Study demonstrated that bacteria accumulated four BPhe a corresponding BChl a. The four BPhe a were mainly distributed in the reaction centers, and their relative content was lower than BChl a. [21] Our study demonstrated that the different concentrations of As affected the relative content of accumulated BPhe a and BChl a. ...
This study aimed to isolate and characterize a new arsenic (As)-tolerant bacterial strain (XJ-1) from the Halosol soil, to evaluate its As tolerance, and to examine the variation in composition and relative content of accumulated photosynthetic pigments in response to As. The experiments were performed with high-performance liquid chromatography (HPLC), inductively-coupled plasma mass spectrometry (ICP-MS), liquid chromatography/mass spectrometry (LC/MS), thin-layer chromatography (TLC) and grayscale intensity image analysis using Gel-Pro analyzer software. Strain XJ-1 was identified as Rhodobacter (R.) capsulatus based on 16S rRNA gene sequencing and physiological characteristics. Strain XJ-1 was able to grow when exposed to arsenite [As(III)] and arsenate [As(V)] under anaerobic-light conditions. The median effective concentrations (EC50) of As(III) and As(V) were 0.61 mM and 2.03 mM, respectively. Strain XJ-1 could reduce As(V) to As(III), but As(III) could not be transformed back to As(V) or other organic As compounds. Accumulation of bacteriochlorophylls and carotenoids in strain XJ-1 varied in the presence of 0.2-1.2 mM As(III) and 0-2.5 mM As(V). As exposure resulted in pronounced variation in compositions and contents of photosynthetic pigments, especially hydroxyspheroidene, bacteriophaeophytin, the ratio of tetrahydrogeranylgeranyl to phytylated BChl a, and the ratio of spheroidene to spheroidenone. This research highlights the adaptative response of R. capsulatus strain XJ-1 photosystems to environmental As, and demonstrates the potential of utilizing the sensitivity of its photosynthetic pigments to As(III) and As(V) for the biodetection of As in the environment.
... Accordingly, the LH2 isolated from acetate-glutamate cultures also exhibited a $423 nm absorption peak [11]. The $423 nm peak, frequently observed in a wide range of absorption spectra [12][13][14], was ill-defined. Since this peak is present in the carotenoid region, it is routinely ascribed to carotenoid. ...
Several spectrally different types of peripheral light harvesting complexes (LH) have been reported in anoxygenic phototrophic bacteria in response to environmental changes. In this study, two spectral forms of LH2 (T-LH2 and U-LH2) were isolated from Rhodobacter azotoformans. The absorption of T-LH2 was extremely similar to the LH2 isolated from Rhodobacter sphaeroides. U-LH2 showed an extra peak at ∼423nm in the carotenoid region. To explore the spectral origin of this absorption peak, the difference in pigment compositions of two LH2 was analyzed. Spheroidene and bacteriochlorophyll aP were both contained in the two LH2. And magnesium protoporphyrin IX monomethyl ester (MPE) was only contained in U-LH2. It is known that spheroidene and bacteriochlorophyll aP do not produce ∼423nm absorption peak either in vivo or in vitro. Whether MPE accumulation was mainly responsible for the formation of the ∼423nm peak? The interactions between MPE and different proteins were further studied. The results showed that the maximum absorption of MPE was red-shifted from ∼415nm to ∼423nm when it was mixed with T-LH2 and its apoproteins, nevertheless, the Qy transitions of the bound bacteriochlorophylls in LH2 were almost unaffected, which indicated that the formation of the ∼423nm peak was related to MPE-LH2 protein interaction. MPE did not bind to sites involved in the spectral tuning of BChls, but the conformation of integral LH2 was affected by MPE association, the alkaline stability of U-LH2 was lower than T-LH2, and the fluorescence intensity at 860nm was decreased after MPE combination.
... The mass spectrum of the three purple bands of A4, B2, and B3 confirmed their identity as bacteriopheophytin with a molecule ion at m/z 889.6. The relative molecular masses of the three green bands of A5, B4, and C3 were 911.6 and consistent with phytylated BChl a p [24,25]. ...
... The most interesting result demonstrated that strain XJ-1 accumulated almost only BChl a (approximately 98% of total BChl contents) anaerobically in the light, aerobically in the light and dark. Harada demonstrated that dihydrogeranylgeranylated BChl a, geranylgeranylated BChl a, phytylated BChl a, and tetrahydrogeranylgeranylated BChl a were always detected as intermediates and were more widely distributed in the purple photosynthetic bacteria [24]. However, compositions of BChl and carotenoids synthesized are variable depending on the culture conditions, such as light intensity, oxygen concentration and growth phases, and also depending on the strain [26]. ...
A Rhodobacter capsulatus strain, designated XJ-1, isolated from saline soil, accumulated almost only one kind of bacteriochlorophyll a anaerobically in the light, aerobically in the light and dark, and the relative contents of the bacteriochlorophyll a were 44.61, 74.89, and 77.53% of the total pigments, respectively. A new purple pigment appeared only in aerobic-light grown cells, exhibited absorption maxima at 355, 389, 520, 621, and 755 nm, especially distinctly unusual peak at 621 nm, whereas vanished in anaerobic-light and in aerobic-dark culture. Spheroidene and OH-spheroidene predominated in anaerobic phototrophic cultures. Spheroidenone was the sole carotenoid when exposed to both light and oxygen. The second keto-carotenoids, OH-spheroidenone, presented only in aerobic-dark culture in addition to spheroidenone. Strain XJ-1 would be a good model organism for the further illustration of the regulation of bacteriochlorophyll biosynthesis gene expression in response to unique habitat.
... Recently, Rhodopseudomonas palustris has served as a model organism to elucidate spectrally different antennae complex (LH1, LH2 and LH4) (5). Moreover, much progresses have been made toward elucidating the final four successive reactions of BChl a biosynthesis (6); four BChl a (BChl a GG , BChl a DHGG , BChl a THGG and BChl a p ) and four bacteriopheophytin (BPhe) coexist in photosynthetic apparatus (7); R. palustris could accumulate five to seven carotenoids in the spirilloxanthin series pathway (8). Therefore, Rhodopseudomonas species have aroused intensive interest in photosynthesis research. ...
... In APB, the changes in absorption spectra could reflect their respective cells' pigment metabolism response to environmental stimulus (6)(7)(8)(9)(10)(11)(12). The characteristic absorption spectra are often used as the taxonomic marker(s). ...
A spectral peak at ~421 nm appeared in vivo spectrum of Rhodopseudomonas palustris CQV97 cultured in acetate-glutamate medium (M1) but not in acetate-ammonium sulfate medium (M2). However, the spectral origin of 421 nm peak was unclear and frequently attributed to carotenoid component(s). In this study, comparative analysis of the extracted components showed that magnesium protoporphyrin IX monomethylester (MPE) was accumulated as one of the predominate components in M1 culture. The amounts of bacteriochlorophyll a in M1 culture were higher than that in M2 while the amounts of carotenoids were nearly identical in both cultures. A simple, rapid and minimum interference with carotenoid and bacteriochlorophyll method to efficiently extract the compounds involving in the formation of 421 nm peak was developed in this study. Assembly of purified MPE with protein components from R. palustris in vitro demonstrated that MPE caused the formation of 421 nm peak. The localization analysis in vivo demonstrated it is MPE associating to protein components and accounting for the peak at ~421 nm. This work clarified the 421 nm peak in vivo mainly originated from MPE accumulation, and will be very helpful to further explore the physiological roles of MPE or its derivatives in photosynthesis.This article is protected by copyright. All rights reserved.
