1
|
Yakovlev AG, Taisova AS. Quenching of bacteriochlorophyll a triplet state by carotenoids in the chlorosome baseplate of green bacterium Chloroflexus aurantiacus. Phys Chem Chem Phys 2024; 26:8815-8823. [PMID: 38421198 DOI: 10.1039/d4cp00287c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2024]
Abstract
To capture weak light fluxes, green photosynthetic bacteria have unique structures - chlorosomes, consisting of 104-5 molecules of bacteriochlorophyll (BChl) c, d, e. Chlorosomes are attached to the cytoplasmic membrane through the baseplate, a paracrystalline protein structure containing BChl a and carotenoids (Car). The most important function of Car is the quenching of triplet states of BChl, which prevents the formation of singlet oxygen and thereby provides photoprotection. In our work, we studied the dynamics of the triplet states of BChl a and Car in the baseplate of Chloroflexus aurantiacus chlorosomes using picosecond differential spectroscopy. BChl a of the baseplate was excited into the Qy band at 810 nm, and the corresponding absorption changes were recorded in the range of 420-880 nm. It was found that the formation of the Car triplet state occurs in ∼1.3 ns, which is ∼3 times faster than the formation of this state in the peripheral antenna of C. aurantiacus according to literature data. The Car triplet state was recorded by the characteristic absorption band T1 → Tn at ∼550 nm. Simultaneously with the appearance of absorption T1 → Tn, there was a bleaching of the singlet absorption of Car in the region of 400-500 nm. Theoretical modeling made it possible to estimate the characteristic time of formation of the triplet state of BChl a as ∼0.5 ns. It is shown that the experimental data are well described by the sequential scheme of formation and quenching of the BChl a triplet state: BChl a* → BChl aT → CarT. Thus, carotenoids from green bacteria effectively protect the baseplate from possible damage by singlet oxygen.
Collapse
Affiliation(s)
- Andrei G Yakovlev
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Leninskie Gory, Moscow 119991, Russian Federation.
| | - Alexandra S Taisova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, Leninskie Gory, Moscow 119991, Russian Federation.
| |
Collapse
|
2
|
Yakovlev AG, Taisova AS, Fetisova ZG. Low-Frequency Oscillations of Bacteriochlorophyll Oligomers in Chlorosomes of Photosynthetic Green Bacteria. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:2084-2093. [PMID: 38462452 DOI: 10.1134/s0006297923120118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 07/17/2023] [Accepted: 09/18/2023] [Indexed: 03/12/2024]
Abstract
In green photosynthetic bacteria, light is absorbed by bacteriochlorophyll (BChl) c/d/e oligomers, which are located in chlorosomes - unique structures created by Nature to collect the energy of very weak light fluxes. Using coherent femtosecond spectroscopy at cryogenic temperature, we detected and studied low-frequency vibrational motions of BChl c oligomers in chlorosomes of the green bacteria Chloroflexus (Cfx.) aurantiacus. The objects of the study were chlorosomes isolated from the bacterial cultures grown under different light intensity. It was found that the Fourier spectrum of low-frequency coherent oscillations in the Qy band of BChl c oligomers depends on the light intensity used for the growth of bacteria. It turned out that the number of low-frequency vibrational modes of chlorosomes increases as illumination under which they were cultivated decreases. Also, the frequency range within which these modes are observed expands, and frequencies of the most modes change. Theoretical modeling of the obtained data and analysis of the literature led to conclusion that the structural basis of Cfx. aurantiacus chlorosomes are short linear chains of BChl c combined into more complex structures. Increase in the length of these chains in chlorosomes grown under weaker light leads to the observed changes in the spectrum of vibrations of BChl c oligomers. This increase is an effective mechanism for bacteria adaptation to changing external conditions.
Collapse
Affiliation(s)
- Andrei G Yakovlev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
| | - Alexandra S Taisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Zoya G Fetisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| |
Collapse
|
3
|
Yakovlev AG, Taisova AS, Fetisova ZG. Femtosecond Exciton Relaxation in Chlorosomes of the Photosynthetic Green Bacterium Chloroflexus aurantiacus. BIOCHEMISTRY. BIOKHIMIIA 2023; 88:704-715. [PMID: 37331716 DOI: 10.1134/s0006297923050139] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/20/2023] [Accepted: 03/31/2023] [Indexed: 06/20/2023]
Abstract
Process of photosynthesis in the green bacteria Chloroflexus (Cfx.) aurantiacus starts from absorption of light by chlorosomes, peripheral antennas consisting of thousands of bacteriochlorophyll c (BChl c) molecules combined into oligomeric structures. In this case, the excited states are formed in BChl c, energy of which migrates along the chlorosome towards the baseplate and further to the reaction center, where the primary charge separation occurs. Energy migration is accompanied by non-radiative electronic transitions between the numerous exciton states, that is, exciton relaxation. In this work, we studied dynamics of the exciton relaxation in Cfx. aurantiacus chlorosomes using differential femtosecond spectroscopy at cryogenic temperature (80 K). Chlorosomes were excited by 20-fs light pulses at wavelengths in the range from 660 to 750 nm, and differential (light-dark) absorption kinetics were measured at a wavelength of 755 nm. Mathematical analysis of the obtained data revealed kinetic components with characteristic times of 140, 220, and 320 fs, which are responsible for exciton relaxation. As the excitation wavelength decreased, the number and relative contribution of these components increased. Theoretical modelling of the obtained data was carried out based of the cylindrical model of BChl c. Nonradiative transitions between the groups of exciton bands were described by a system of kinetic equations. The model that takes into account energy and structural disorder of chlorosomes turned out to be the most adequate.
Collapse
Affiliation(s)
- Andrei G Yakovlev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
| | - Alexandra S Taisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| | - Zoya G Fetisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia
| |
Collapse
|
4
|
Gonzalez-Nayeck AC, Mohr W, Tang T, Sattin S, Parenteau MN, Jahnke LL, Pearson A. Absence of canonical trophic levels in a microbial mat. GEOBIOLOGY 2022; 20:726-740. [PMID: 35831948 DOI: 10.1111/gbi.12511] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/21/2022] [Revised: 06/16/2022] [Accepted: 06/26/2022] [Indexed: 06/15/2023]
Abstract
In modern ecosystems, the carbon stable isotope (δ13 C) ratios of consumers generally conform to the principle "you are what you eat, +1‰." However, this metric may not apply to microbial mat systems where diverse communities, using a variety of carbon substrates via multiple assimilation pathways, live in close physical association and phagocytosis is minimal or absent. To interpret the δ13 C record of the Proterozoic and early Paleozoic, when mat-based productivity likely was widespread, it is necessary to understand how a microbially driven producer-consumer structure affects the δ13 C compositions of biomass and preservable lipids. Protein Stable Isotope Fingerprinting (P-SIF) is a recently developed method that allows measurement of the δ13 C values of whole proteins, separated from environmental samples and identified taxonomically via proteomics. Here, we use P-SIF to determine the trophic relationships in a microbial mat sample from Chocolate Pots Hot Springs, Yellowstone National Park (YNP), USA. In this mat, proteins from heterotrophic bacteria are indistinguishable from cyanobacterial proteins, indicating that "you are what you eat, +1‰" is not applicable. To explain this finding, we hypothesize that sugar production and consumption dominate the net ecosystem metabolism, yielding a community in which producers and consumers share primary photosynthate as a common resource. This idea was validated by confirming that glucose moieties in exopolysaccharide were equal in δ13 C composition to both cyanobacterial and heterotrophic proteins, and by confirming that highly 13 C-depleted fatty acids (FAs) of Cyanobacteria dominate the lipid pool, consistent with flux-balance expectations for systems that overproduce primary photosynthate. Overall, the results confirm that the δ13 C composition of microbial biomass and lipids is tied to specific metabolites, rather than to autotrophy versus heterotrophy or to individual trophic levels. Therefore, we suggest that aerobic microbial heterotrophy is simply a case of "you are what you eat."
Collapse
Affiliation(s)
- Ana C Gonzalez-Nayeck
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
| | - Wiebke Mohr
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
- Max-Planck-Institute for Marine Microbiology, Bremen, Germany
| | - Tiantian Tang
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
- State Key Laboratory of Marine Environmental Science (Xiamen University), Xiamen, Fujian, China
- College of Ocean and Earth Sciences, Xiamen University, Xiamen, Fujian, China
| | - Sarah Sattin
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
| | | | - Linda L Jahnke
- NASA Ames Research Center, Moffett Field, California, USA
| | - Ann Pearson
- Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts, USA
| |
Collapse
|
5
|
Utilization of blue-green light by chlorosomes from the photosynthetic bacterium Chloroflexus aurantiacus: Ultrafast excitation energy conversion and transfer. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 2021; 1862:148396. [PMID: 33581107 DOI: 10.1016/j.bbabio.2021.148396] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Revised: 02/01/2021] [Accepted: 02/05/2021] [Indexed: 01/14/2023]
Abstract
Chlorosomes of photosynthetic green bacteria are unique molecular assemblies providing efficient light harvesting followed by multi-step transfer of excitation energy to reaction centers. In each chlorosome, 104-105 bacteriochlorophyll (BChl) c/d/e molecules are organized by self-assembly into high-ordered aggregates. We studied the early-time dynamics of the excitation energy flow and energy conversion in chlorosomes isolated from Chloroflexus (Cfx.) aurantiacus bacteria by pump-probe spectroscopy with 30-fs temporal resolution at room temperature. Both the S2 state of carotenoids (Cars) and the Soret states of BChl c were excited at ~490 nm, and absorption changes were probed at 400-900 nm. A global analysis of spectroscopy data revealed that the excitation energy transfer (EET) from Cars to BChl c aggregates occurred within ~100 fs, and the Soret → Q energy conversion in BChl c occurred faster within ~40 fs. This conclusion was confirmed by a detailed comparison of the early exciton dynamics in chlorosomes with different content of Cars. These processes are accompanied by excitonic and vibrational relaxation within 100-270 fs. The well-known EET from BChl c to the baseplate BChl a proceeded on a ps time-scale. We showed that the S1 state of Cars does not participate in EET. We discussed the possible presence (or absence) of an intermediate state that might mediates the Soret → Qy internal conversion in chlorosomal BChl c. We discussed a possible relationship between the observed exciton dynamics and the structural heterogeneity of chlorosomes.
Collapse
|
6
|
Sparks WB, Parenteau MN, Blankenship RE, Germer TA, Patty CHL, Bott KM, Telesco CM, Meadows VS. Spectropolarimetry of Primitive Phototrophs as Global Surface Biosignatures. ASTROBIOLOGY 2021; 21:219-234. [PMID: 33216615 PMCID: PMC7876348 DOI: 10.1089/ast.2020.2272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 10/12/2020] [Indexed: 06/11/2023]
Abstract
Photosynthesis is an ancient metabolic process that began on early Earth and offers plentiful energy to organisms that can utilize it such that that they achieve global significance. The potential exists for similar processes to operate on habitable exoplanets and result in observable biosignatures. Before the advent of oxygenic photosynthesis, the most primitive phototrophs, anoxygenic phototrophs, dominated surface environments on the planet. Here, we characterize surface polarization biosignatures associated with a diverse sample of anoxygenic phototrophs and cyanobacteria, examining both pure cultures and microbial communities from the natural environment. Polarimetry is a tool that can be used to measure the chiral signature of biomolecules. Chirality is considered a universal, agnostic biosignature that is independent of a planet's biochemistry, receiving considerable interest as a target biosignature for life-detection missions. In contrast to preliminary indications from earlier work, we show that there is a diversity of distinctive circular polarization signatures, including the magnitude of the polarization, associated with the variety of chiral photosynthetic pigments and pigment complexes of anoxygenic and oxygenic phototrophs. We also show that the apparent death and release of pigments from one of the phototrophs is accompanied by an elevation of the reflectance polarization signal by an order of magnitude, which may be significant for remotely detectable environmental signatures. This work and others suggest that circular polarization signals up to ∼1% may occur, significantly stronger than previously anticipated circular polarization levels. We conclude that global surface polarization biosignatures may arise from anoxygenic and oxygenic phototrophs, which have dominated nearly 80% of the history of our rocky, inhabited planet.
Collapse
Affiliation(s)
- William B. Sparks
- SETI Institute, Mountain View, California, USA
- Space Telescope Science Institute, Baltimore, Maryland, USA
| | - Mary Niki Parenteau
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- NASA Ames Research Center, Moffett Field, California, USA
| | - Robert E. Blankenship
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Thomas A. Germer
- National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Christian Herman Lucas Patty
- Institute of Plant Biology, Hungarian Academy of Sciences, Szeged, Hungary
- Space Research and Planetary Sciences, University of Bern, Bern, Switzerland
| | - Kimberly M. Bott
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Department of Earth and Planetary Sciences, University of California, Riverside, Riverside, California, USA
| | - Charles M. Telesco
- Department of Astronomy, University of Florida, Gainesville, Florida, USA
| | - Victoria S. Meadows
- Virtual Planetary Laboratory, University of Washington, Seattle, Washington, USA
- Department of Astronomy, University of Washington, Seattle, Washington, USA
| |
Collapse
|
7
|
Yakovlev AG, Taisova AS, Fetisova ZG. Q-band hyperchromism and B-band hypochromism of bacteriochlorophyll c as a tool for investigation of the oligomeric structure of chlorosomes of the green photosynthetic bacterium Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 2020; 146:95-108. [PMID: 31939070 DOI: 10.1007/s11120-019-00707-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 12/31/2019] [Indexed: 06/10/2023]
Abstract
Chlorosomes of green photosynthetic bacteria are the most amazing example of long-range ordered natural light-harvesting antennae. Chlorosomes are the largest among all known photosynthetic light-harvesting structures (~ 104-105 pigments in the aggregated state). The chlorosomal bacteriochlorophyll (BChl) c/d/e molecules are organized via self-assembly and do not require proteins to provide a scaffold for efficient light harvesting. Despite numerous investigations, a consensus regarding the spatial structure of chlorosomal antennae has not yet been reached. In the present work, we studied hyperchromism/hypochromism in the chlorosomal BChl c Q/B absorption bands of the green photosynthetic bacterium Chloroflexus (Cfx.) aurantiacus. The chlorosomes were isolated from cells grown under different light intensities and therefore, as we discovered earlier, they had different sizes of both BChl c antennae and their unit building blocks. We have shown experimentally that the Q-/B-band hyperchromism/hypochromism is proportional to the size of the chlorosomal antenna. We explained theoretically these findings in terms of excitonic intensity borrowing between the Q and B bands for the J-/H-aggregates of the BChls. The theory developed by Gülen (Photosynth Res 87:205-214, 2006) showed the dependence of the Q-/B-band hyperchromism/hypochromism on the structure of the aggregates. For the model of exciton-coupled BChl c linear chains within a unit building block, the theory predicted an increase in the hyperchromism/hypochromism with the increase in the number of molecules per chain and a decrease in it with the increase in the number of chains. It was previously shown that this model ensured a good fit with spectroscopy experiments and approximated the BChl c low packing density in vivo. The presented experimental and theoretical studies of the Q-/B-band hyperchromism/hypochromism permitted us to conclude that the unit building block of Cfx. aurantiacus chlorosomes comprises of several short BChl c chains.This conclusion is in accordance with previous linear and nonlinear spectroscopy studies on Cfx. aurantiacus chlorosomes.
Collapse
Affiliation(s)
- Andrei G Yakovlev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991.
| | - Alexandra S Taisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991
| | - Zoya G Fetisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991.
| |
Collapse
|
8
|
Taniguchi M, Lindsey JS. Absorption and Fluorescence Spectral Database of Chlorophylls and Analogues. Photochem Photobiol 2020; 97:136-165. [PMID: 32757305 DOI: 10.1111/php.13319] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 07/28/2020] [Accepted: 07/30/2020] [Indexed: 12/29/2022]
Abstract
Absorption spectra and fluorescence spectra are essential for use across the photosciences, yet such spectra along with the all-important values for molar absorption coefficient (ε) and fluorescence quantum yield (Φf ) often are found with great difficulty. Here, a literature survey concerning the vital class of chlorophyll compounds has led to identification of spectra for 150 members. Spectra in print form have been digitized (with baseline corrections) and assembled into a database along with literature references, solvent identity and values for ε and Φf (where available). The database encompasses photosynthetic tetrapyrroles wherein the chromophore is a porphyrin (e.g. chlorophyll c1 , protochlorophyll a), chlorin (e.g. chlorophyll a, bacteriochlorophyll c) or bacteriochlorin (e.g. bacteriochlorophyll a). Altogether, the database contains 305 absorption spectra (from 19 porphyrins, 109 chlorins and 22 bacteriochlorins) and 72 fluorescence spectra (from 10 porphyrins, 30 chlorins and 4 bacteriochlorins). The spectral database should facilitate comparisons and quantitative calculations. All spectra are available in print form in the Supporting Information. The entire database in digital form is available with the PhotochemCAD program for free downloading and further use at http://www.photochemcad.com.
Collapse
|
9
|
Wörmer L, Gajendra N, Schubotz F, Matys ED, Evans TW, Summons RE, Hinrichs KU. A micrometer-scale snapshot on phototroph spatial distributions: mass spectrometry imaging of microbial mats in Octopus Spring, Yellowstone National Park. GEOBIOLOGY 2020; 18:742-759. [PMID: 32936514 DOI: 10.1111/gbi.12411] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2020] [Revised: 07/10/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Microbial mats from alkaline hot springs in the Yellowstone National Park are ideal natural laboratories to study photosynthetic life under extreme conditions, as well as the nuanced interactions of oxygenic and anoxygenic phototrophs. They represent distinctive examples of chlorophototroph (i.e., chlorophyll or bacteriochlorophyll-based phototroph) diversity, and several novel phototrophs have been first described in these systems, all confined in space, coexisting and competing for niches defined by parameters such as light, oxygen, or temperature. In a novel approach, we employed mass spectrometry imaging of chloropigments, quinones, and intact polar lipids (IPLs) to describe the spatial distribution of different groups of chlorophototrophs along the ~ 1 cm thick microbial mat at 75 µm resolution and in the top ~ 1.5 mm green part of the mat at 25 µm resolution. We observed a fine-tuned sequence of oxygenic and anoxygenic chlorophototrophs with distinctive biomarker signatures populating the microbial mat. The transition of oxic to anoxic conditions is characterized by an accumulation of biomarkers indicative of anoxygenic phototrophy. It is also identified as a clear boundary for different species and ecotypes, which adjust their biomarker inventory, particularly the interplay of quinones and chloropigments, to prevailing conditions. Colocalization of the different biomarker groups led to the identification of characteristic IPL signatures and indicates that glycosidic diether glycerolipids are diagnostic for anoxygenic phototrophs in this mat system. The zoom-in into the upper green part further reveals how oxygenic and anoxygenic phototrophs share this microenvironment and informs on subtle, microscale adjustments in lipid composition of Synechococcus spp.
Collapse
Affiliation(s)
- Lars Wörmer
- MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Niroshan Gajendra
- MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, Germany
- Department of Environmental Systems Science, ETH Zürich, Zürich, Switzerland
| | - Florence Schubotz
- MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, Germany
| | - Emily D Matys
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Thomas W Evans
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Roger E Summons
- Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Kai-Uwe Hinrichs
- MARUM - Center for Marine Environmental Sciences and Faculty of Geosciences, University of Bremen, Bremen, Germany
| |
Collapse
|
10
|
Yakovlev AG, Taisova AS, Shuvalov VA, Fetisova ZG. Ultrafast excited-state dynamics in chlorosomes isolated from the photosynthetic filamentous green bacterium Chloroflexus aurantiacus. PHYSIOLOGIA PLANTARUM 2019; 166:12-21. [PMID: 30499123 DOI: 10.1111/ppl.12887] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2018] [Revised: 11/24/2018] [Accepted: 11/26/2018] [Indexed: 06/09/2023]
Abstract
Bacteriochlorophyll (BChl) c pigments in the aggregated state are responsible for efficient light harvesting in chlorosomes of the filamentous anoxygenic photosynthetic bacterium, Chloroflexus (Cfx.) aurantiacus. Absorption of light creates excited states in the BChl c aggregates. After subpicosecond intrachlorosomal energy transfer, redistribution and relaxation, the excitation is transferred to the BChl a complexes and further to reaction centers on the picosecond time scale. In this work, the femtosecond excited state dynamics within BChl c oligomers of isolated Cfx. aurantiacus chlorosomes was studied by double difference pump-probe spectroscopy at room temperature. Difference (Alight - Adark ) spectra corresponding to excitation at 725 nm (blue side of the BChl c absorption band) were compared with those corresponding to excitation at 750 nm (red side of the BChl c absorption band). A very fast (time constant 70 ± 10 fs) rise kinetic component was found in the stimulated emission (SE) upon excitation at 725 nm. This component was absent at 750-nm excitation. These data were explained by the dynamical red shift of the SE due to excited state relaxation. The nature and mechanisms of the ultrafast excited state dynamics in chlorosomal BChl c aggregates are discussed.
Collapse
Affiliation(s)
- Andrei G Yakovlev
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, 119991, Moscow, Russian Federation
| | - Alexandra S Taisova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, 119991, Moscow, Russian Federation
| | - Vladimir A Shuvalov
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, 119991, Moscow, Russian Federation
- Institute of Basic Biological Problems, Russian Academy of Sciences, 142290, Moscow, Russian Federation
| | - Zoya G Fetisova
- Lomonosov Moscow State University, Belozersky Institute of Physico-Chemical Biology, 119991, Moscow, Russian Federation
| |
Collapse
|
11
|
Yakovlev A, Taisova A, Shuvalov V, Fetisova Z. Estimation of the bacteriochlorophyll c oligomerisation extent in Chloroflexus aurantiacus chlorosomes by very low-frequency vibrations of the pigment molecules: A new approach. Biophys Chem 2018; 240:1-8. [DOI: 10.1016/j.bpc.2018.05.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Revised: 05/14/2018] [Accepted: 05/19/2018] [Indexed: 10/16/2022]
|
12
|
Yakovlev A, Taisova A, Arutyunyan A, Shuvalov V, Fetisova Z. Variability of aggregation extent of light-harvesting pigments in peripheral antenna of Chloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 2017; 133:343-356. [PMID: 28361448 DOI: 10.1007/s11120-017-0374-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2016] [Accepted: 03/21/2017] [Indexed: 06/07/2023]
Abstract
The stationary ground state and femtosecond time-resolved absorption spectra as well as spectra of circular dichroism were measured at room temperature using freshly prepared samples of chlorosomes isolated from fresh cultures of the green bacterium Chloroflexus aurantiacus. Cultures were grown by using as inoculum the same seed culture but under different light conditions. All measured spectra clearly showed the red shift of BChl c Qy bands (up to 5 nm) for low-light chlorosomes as compared to high-light ones, together with concomitant narrowing of these bands and increasing of their amplitudes. The sizes of the unit BChl c aggregates of the high-light-chlorosomes and the low-light ones were estimated. The fit of all experimental spectra was obtained within the framework of our model proposed before (Fetisova et al., Biophys J 71:995-101, 1996). The model assumes that a unit building block of the BChl c antenna has a form of a tubular aggregate of L = 6 linear single or double exciton-coupled pigment chains within a rod element, with the pigment packing density, approximating that in vivo. The simultaneous fit of all experimental spectra gave the number of pigments in each individual linear pigment chain N = 4 and N = 6 for the high-light and the low-light BChl c unit building blocks, respectively. The size of a unit building block in the BChl c antenna was found to vary from L × N = 24 to L × N = 36 exciton-coupled BChl c molecules being governed by the growth-light intensity. All sets of findings for Chloroflexus aurantiacus chlorosomes demonstrated the biologically expedient light-controlled variability, predicted by us, of the extent of BChl c aggregation within a unit building block in this antenna.
Collapse
Affiliation(s)
- Andrei Yakovlev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991.
| | - Alexandra Taisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991
| | - Alexander Arutyunyan
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991
| | - Vladimir Shuvalov
- Institute of Basic Biological Problems, Russian Academy of Sciences, Pushchino, Moscow Region, Russian Federation, 142290
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991
| | - Zoya Fetisova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, Moscow, Russian Federation, 119991.
| |
Collapse
|
13
|
Yakovlev A, Novoderezhkin V, Taisova A, Shuvalov V, Fetisova Z. Orientation of B798 BChl a Q y transition dipoles in Chloroflexus aurantiacus chlorosomes: polarized transient absorption spectroscopy studies. PHOTOSYNTHESIS RESEARCH 2015; 125:31-42. [PMID: 25515768 DOI: 10.1007/s11120-014-0060-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2014] [Accepted: 11/16/2014] [Indexed: 06/04/2023]
Abstract
Isotropic and anisotropic pump-probe spectra of Cfx. aurantiacus chlorosomes were measured on the fs-through ps-time scales for the B798 BChl a Q y band upon direct excitation of the B798 band at T = 293 K and T = 90 K. Upon direct excitation of the B798 band, the anisotropy parameter value r(λ) was constant within the whole BChl a Q y band at any delay time at both temperatures. The value of the anisotropy parameter r decayed from r = 0.4 at both temperatures (at 200 fs delay time after excitation) to the steady-state values r = 0.1 at T = 293 K and to r = 0.09 at T = 90 K (at 30 ÷ 100 ps delay time after excitation). The results were considered within the framework of the model of uniaxial orientation distribution of BChl-a transition dipoles within a single Cfx. aurantiacus chlorosome. This implies that the B798 BChl a Q y transition dipoles, randomly distributed around the normal to the baseplate plane, form the angle θ with the plane. For this model, the theoretical dependence of the steady-state anisotropy parameter r on the angle θ was derived. According to the theoretical dependence r(θ), the angle θ corresponding to the experimental steady-state value r = 0.1 at T = 293 K was found to equal 55°. As the temperature drops to 90 K, the angle θ decreases to 54°.
Collapse
Affiliation(s)
- Andrei Yakovlev
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Leninskie Gory, 119991, Moscow, Russian Federation
| | | | | | | | | |
Collapse
|
14
|
Taisova AS, Yakovlev AG, Fetisova ZG. Size variability of the unit building block of peripheral light-harvesting antennas as a strategy for effective functioning of antennas of variable size that is controlled in vivo by light intensity. BIOCHEMISTRY (MOSCOW) 2014; 79:251-9. [PMID: 24821452 DOI: 10.1134/s0006297914030110] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
This work continuous a series of studies devoted to discovering principles of organization of natural antennas in photosynthetic microorganisms that generate in vivo large and highly effective light-harvesting structures. The largest antenna is observed in green photosynthesizing bacteria, which are able to grow over a wide range of light intensities and adapt to low intensities by increasing of size of peripheral BChl c/d/e antenna. However, increasing antenna size must inevitably cause structural changes needed to maintain high efficiency of its functioning. Our model calculations have demonstrated that aggregation of the light-harvesting antenna pigments represents one of the universal structural factors that optimize functioning of any antenna and manage antenna efficiency. If the degree of aggregation of antenna pigments is a variable parameter, then efficiency of the antenna increases with increasing size of a single aggregate of the antenna. This means that change in degree of pigment aggregation controlled by light-harvesting antenna size is biologically expedient. We showed in our previous work on the oligomeric chlorosomal BChl c superantenna of green bacteria of the Chloroflexaceae family that this principle of optimization of variable antenna structure, whose size is controlled by light intensity during growth of bacteria, is actually realized in vivo. Studies of this phenomenon are continued in the present work, expanding the number of studied biological materials and investigating optical linear and nonlinear spectra of chlorosomes having different structures. We show for oligomeric chlorosomal superantennas of green bacteria (from two different families, Chloroflexaceae and Oscillochloridaceae) that a single BChl c aggregate is of small size, and the degree of BChl c aggregation is a variable parameter, which is controlled by the size of the entire BChl c superantenna, and the latter, in turn, is controlled by light intensity in the course of cell culture growth.
Collapse
Affiliation(s)
- A S Taisova
- Belozersky Research Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, 119992, Russia.
| | | | | |
Collapse
|
15
|
Olson JB, Gao X. Characterizing the bacterial associates of three Caribbean sponges along a gradient from shallow to mesophotic depths. FEMS Microbiol Ecol 2013; 85:74-84. [DOI: 10.1111/1574-6941.12099] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2013] [Revised: 02/05/2013] [Accepted: 02/15/2013] [Indexed: 10/27/2022] Open
Affiliation(s)
- Julie B. Olson
- Department of Biological Sciences; The University of Alabama; Tuscaloosa; AL; USA
| | - Xumin Gao
- Department of Biological Sciences; The University of Alabama; Tuscaloosa; AL; USA
| |
Collapse
|
16
|
Horath T, Bachofen R. Molecular characterization of an endolithic microbial community in dolomite rock in the central Alps (Switzerland). MICROBIAL ECOLOGY 2009; 58:290-306. [PMID: 19172216 DOI: 10.1007/s00248-008-9483-7] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2008] [Accepted: 12/19/2008] [Indexed: 05/21/2023]
Abstract
Endolithic microorganisms colonize the pores in exposed dolomite rocks in the Piora Valley in the Swiss Alps. They appear as distinct grayish-green bands about 1-8 mm below the rock surface. Based on environmental small subunit ribosomal RNA gene sequences, a diverse community driven by photosynthesis has been found. Cyanobacteria (57 clones), especially the genus Leptolyngbya, form the functional basis for an endolithic community which contains a wide spectrum of so far not characterized species of chemotrophic Bacteria (64 clones) with mainly Actinobacteria, Alpha-Proteobacteria, Bacteroidetes, and Acidobacteria, as well as a cluster within the Chloroflexaceae. Furthermore, a cluster within the Crenarchaeotes (40 clones) has been detected. Although the eukaryotic diversity was outside the scope of the study, an amoeba (39 clones), and several green algae (51 clones) have been observed. We conclude that the bacterial diversity in this endolithic habitat, especially of chemotrophic, nonpigmented organisms, is considerable and that Archaea are present as well.
Collapse
Affiliation(s)
- Thomas Horath
- Institute of Plant Biology/Microbiology, University of Zürich, Zollikerstr. 107, CH-8008 Zürich, Switzerland
| | | |
Collapse
|
17
|
Differential microbial communities in hot spring mats from Western Thailand. Extremophiles 2008; 13:321-31. [DOI: 10.1007/s00792-008-0219-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Accepted: 12/03/2008] [Indexed: 11/27/2022]
|
18
|
Bachar A, Polerecky L, Fischer JP, Vamvakopoulos K, De Beer D, Jonkers HM. Two-dimensional mapping of photopigment distribution and activity of Chloroflexus-like bacteria in a hypersaline microbial mat. FEMS Microbiol Ecol 2008; 65:434-48. [DOI: 10.1111/j.1574-6941.2008.00534.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
|
19
|
Klatt CG, Bryant DA, Ward DM. Comparative genomics provides evidence for the 3-hydroxypropionate autotrophic pathway in filamentous anoxygenic phototrophic bacteria and in hot spring microbial mats. Environ Microbiol 2007; 9:2067-78. [PMID: 17635550 DOI: 10.1111/j.1462-2920.2007.01323.x] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Stable carbon isotope signatures of diagnostic lipid biomarkers have suggested that Roseiflexus spp., the dominant filamentous anoxygenic phototrophic bacteria inhabiting microbial mats of alkaline siliceous hot springs, may be capable of fixing bicarbonate via the 3-hydroxypropionate pathway, which has been characterized in their distant relative, Chloroflexus aurantiacus. The genomes of three filamentous anoxygenic phototrophic Chloroflexi isolates (Roseiflexus sp. RS-1, Roseiflexus castenholzii and Chloroflexus aggregans), but not that of a non-photosynthetic Chloroflexi isolate (Herpetosiphon aurantiacus), were found to contain open reading frames that show a high degree of sequence similarity to genes encoding enzymes in the C. aurantiacus pathway. Metagenomic DNA sequences from the microbial mats of alkaline siliceous hot springs also contain homologues of these genes that are highly similar to genes in both Roseiflexus spp. and Chloroflexus spp. Thus, Roseiflexus spp. appear to have the genetic capacity for carbon dioxide reduction via the 3-hydroxypropionate pathway. This may contribute to heavier carbon isotopic signatures of the cell components of native Roseiflexus populations in mats compared with the signatures of cyanobacterial cell components, as a similar isotopic signature would be expected if Roseiflexus spp. were participating in photoheterotrophic uptake of cyanobacterial photosynthate produced by the reductive pentose phosphate cycle.
Collapse
Affiliation(s)
- Christian G Klatt
- Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, USA.
| | | | | |
Collapse
|
20
|
Bachar A, Omoregie E, de Wit R, Jonkers HM. Diversity and function of Chloroflexus-like bacteria in a hypersaline microbial mat: phylogenetic characterization and impact on aerobic respiration. Appl Environ Microbiol 2007; 73:3975-83. [PMID: 17449697 PMCID: PMC1932729 DOI: 10.1128/aem.02532-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Accepted: 04/11/2007] [Indexed: 11/20/2022] Open
Abstract
We studied the diversity of Chloroflexus-like bacteria (CLB) in a hypersaline phototrophic microbial mat and assayed their near-infrared (NIR) light-dependent oxygen respiration rates. PCR with primers that were reported to specifically target the 16S rRNA gene from members of the phylum Chloroflexi resulted in the recovery of 49 sequences and 16 phylotypes (sequences of the same phylotype share more than 96% similarity), and 10 of the sequences (four phylotypes) appeared to be related to filamentous anoxygenic phototrophic members of the family Chloroflexaceae. Photopigment analysis revealed the presence of bacteriochlorophyll c (BChlc), BChld, and gamma-carotene, pigments known to be produced by phototrophic CLB. Oxygen microsensor measurements for intact mats revealed a NIR (710 to 770 nm) light-dependent decrease in aerobic respiration, a phenomenon that we also observed in an axenic culture of Chloroflexus aurantiacus. The metabolic ability of phototrophic CLB to switch from anoxygenic photosynthesis under NIR illumination to aerobic respiration under non-NIR illumination was further used to estimate the contribution of these organisms to mat community respiration. Steady-state oxygen profiles under dark conditions and in the presence of visible (VIS) light (400 to 700 nm), NIR light (710 to 770 nm), and VIS light plus NIR light were compared. NIR light illumination led to a substantial increase in the oxygen concentration in the mat. The observed impact on oxygen dynamics shows that CLB play a significant role in the cycling of carbon in this hypersaline microbial mat ecosystem. This study further demonstrates that the method applied, a combination of microsensor techniques and VIS and NIR illumination, allows rapid establishment of the presence and significance of CLB in environmental samples.
Collapse
Affiliation(s)
- Ami Bachar
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | | | | | | |
Collapse
|
21
|
Olson TL, van de Meene AML, Francis JN, Pierson BK, Blankenship RE. Pigment analysis of "Candidatus Chlorothrix halophila," a green filamentous anoxygenic phototrophic bacterium. J Bacteriol 2007; 189:4187-95. [PMID: 17369304 PMCID: PMC1913391 DOI: 10.1128/jb.01712-06] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2006] [Accepted: 02/27/2007] [Indexed: 11/20/2022] Open
Abstract
The pigment composition of "Candidatus Chlorothrix halophila," a filamentous anoxygenic phototrophic bacterium found in Baja California Sur, Mexico, was determined. Previous work showed that bacteriochlorophyll c (BChl c) was the major pigment in "Ca. Chlorothrix halophila," but it was not clear if this bacterium also contains BChl a (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181:17-25, 2004). Here we show that in addition to BChl c, a small amount of a pigment that is spectrally indistinguishable from BChl a is present in cell extracts of "Ca. Chlorothrix halophila." Nevertheless, the BChl a-like pigment from "Ca. Chlorothrix halophila" has a different molecular weight and a different high-performance liquid chromatography elution time than BChl a from other photosynthetic bacteria. Based on mass spectrometry and other spectroscopic analysis, we determined that the BChl a-like pigment in "Ca. Chlorothrix halophila" contains a tetrahydrogeranylgeraniol tail rather than the phytol tail that is present in BChl a. The carotenoids and major BChl c homologs in "Ca. Chlorothrix halophila" were also identified. BChls c were found to be farnesol esterified and geranylgeraniol esterified.
Collapse
Affiliation(s)
- Tien Le Olson
- Department of Biology and Chemistry, Arizona State University, Tempe, AZ 85287, USA
| | | | | | | | | |
Collapse
|
22
|
Tokita S, Frigaard NU, Hirota M, Shimada K, Matsuura K. Quenching of Bacteriochlorophyll Fluorescence in Chlorosomes from Chloroflexus aurantiacus by Exogenous Quinones ¶. Photochem Photobiol 2007. [DOI: 10.1562/0031-8655(2000)0720345qobfic2.0.co2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
|
23
|
van der Meer MTJ, Schouten S, Damsté JSS, Ward DM. Impact of carbon metabolism on 13C signatures of cyanobacteria and green non-sulfur-like bacteria inhabiting a microbial mat from an alkaline siliceous hot spring in Yellowstone National Park (USA). Environ Microbiol 2007; 9:482-91. [PMID: 17222146 DOI: 10.1111/j.1462-2920.2006.01165.x] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Alkaline siliceous hot spring microbial mats in Yellowstone National Park are composed of two dominant phototropic groups, cyanobacteria and green non-sulfur-like bacteria (GNSLB). While cyanobacteria are thought to cross-feed low-molecular-weight organic compounds to support photoheterotrophic metabolism in GNSLB, it is unclear how this could lead to the heavier stable carbon isotopic signatures in GNSLB lipids compared with cyanobacterial lipids found in previous studies. The two groups of phototrophs were separated using percoll density gradient centrifugation and subsequent lipid and stable carbon isotopic analysis revealed that we obtained fractions with a approximately 60-fold enrichment in cyanobacterial and an approximately twofold enrichment in GNSLB biomass, respectively, compared with the mat itself. This technique was used to study the diel cycling and 13C content of the glucose pools in and the uptake of 13C-bicarbonate by the cyanobacteria and GNSLB, as well as the transfer of incorporated 13C from cyanobacteria to GNSLB. The results show that cyanobacteria have the highest bicarbonate uptake rates and accumulate glucose during the afternoon in full light conditions. In contrast, GNSLB have relatively higher bicarbonate uptake rates compared with cyanobacteria in the morning at low light levels. During the night GNSLB take up carbon that is likely derived through fermentation of cyanobacterial glucose enriched in 13C. The assimilation of 13C-enriched cyanobacterial carbon may thus lead to enriched 13C-contents of GNSLB cell components.
Collapse
Affiliation(s)
- Marcel T J van der Meer
- Royal Netherlands Institute for Sea Research (NIOZ), Department of Marine Biogeochemistry and Toxicology, PO Box 59, 1790 AB Den Burg, Texel, the Netherlands
| | | | | | | |
Collapse
|
24
|
van de Meene AML, Le Olson T, Collins AM, Blankenship RE. Initial characterization of the photosynthetic apparatus of "Candidatus Chlorothrix halophila," a filamentous, anoxygenic photoautotroph. J Bacteriol 2007; 189:4196-203. [PMID: 17369303 PMCID: PMC1913384 DOI: 10.1128/jb.01711-06] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
"Candidatus Chlorothrix halophila" is a recently described halophilic, filamentous, anoxygenic photoautotroph (J. A. Klappenbach and B. K. Pierson, Arch. Microbiol. 181:17-25, 2004) that was enriched from the hypersaline microbial mats at Guerrero Negro, Mexico. Analysis of the photosynthetic apparatus by negative staining, spectroscopy, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated that the photosynthetic apparatus in this organism has similarities to the photosynthetic apparatus in both the Chloroflexi and Chlorobi phyla of green photosynthetic bacteria. The chlorosomes were found to be ellipsoidal and of various sizes, characteristics that are comparable to characteristics of chlorosomes in other species of green photosynthetic bacteria. The absorption spectrum of whole cells was dominated by the chlorosome bacteriochlorophyll c (BChl c) peak at 759 nm, with fluorescence emission at 760 nm. A second fluorescence emission band was observed at 870 nm and was tentatively attributed to a membrane-bound antenna complex. Fluorescence emission spectra obtained at 77 K revealed another complex that fluoresced at 820 nm, which probably resulted from the chlorosome baseplate complex. All of these results suggest that BChl c is present in the chlorosomes of "Ca. Chlorothrix halophila," that BChl a is present in the baseplate, and that there is a membrane-bound antenna complex. Analysis of the proteins in the chlorosomes revealed an approximately 6-kDa band, which was found to be related to the BChl c binding protein CsmA found in other green bacteria. Overall, the absorbance and fluorescence spectra of "Ca. Chlorothrix halophila" revealed an interesting mixture of photosynthetic characteristics that seemed to have properties similar to properties of both phyla of green bacteria when they were compared to the photosynthetic characteristics of Chlorobium tepidum and Chloroflexus aurantiacus.
Collapse
|
25
|
Friedmann S, Alber BE, Fuchs G. Properties of R-citramalyl-coenzyme A lyase and its role in the autotrophic 3-hydroxypropionate cycle of Chloroflexus aurantiacus. J Bacteriol 2007; 189:2906-14. [PMID: 17259315 PMCID: PMC1855784 DOI: 10.1128/jb.01620-06] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The autotrophic CO(2) fixation pathway (3-hydroxypropionate cycle) in Chloroflexus aurantiacus results in the fixation of two molecules of bicarbonate into one molecule of glyoxylate. Glyoxylate conversion to the CO(2) acceptor molecule acetyl-coenzyme A (CoA) requires condensation with propionyl-CoA (derived from one molecule of acetyl-CoA and one molecule of CO(2)) to beta-methylmalyl-CoA, which is converted to citramalyl-CoA. Extracts of autotrophically grown cells contained both S- and R-citramalyl-CoA lyase activities, which formed acetyl-CoA and pyruvate. Pyruvate is taken out of the cycle and used for cellular carbon biosynthesis. Both the S- and R-citramalyl-CoA lyases were up-regulated severalfold during autotrophic growth. S-Citramalyl-CoA lyase activity was found to be due to l-malyl-CoA lyase/beta-methylmalyl-CoA lyase. This promiscuous enzyme is involved in the CO(2) fixation pathway, forms acetyl-CoA and glyoxylate from l-malyl-CoA, and condenses glyoxylate with propionyl-CoA to beta-methylmalyl-CoA. R-Citramalyl-CoA lyase was further studied. Its putative gene was expressed and the recombinant protein was purified. This new enzyme belongs to the 3-hydroxy-3-methylglutaryl-CoA lyase family and is a homodimer with 34-kDa subunits that was 10-fold stimulated by adding Mg(2) or Mn(2+) ions and dithioerythritol. The up-regulation under autotrophic conditions suggests that the enzyme functions in the ultimate step of the acetyl-CoA regeneration route in C. aurantiacus. Genes similar to those involved in CO(2) fixation in C. aurantiacus, including an R-citramalyl-CoA lyase gene, were found in Roseiflexus sp., suggesting the operation of the 3-hydroxypropionate cycle in this bacterium. Incomplete sets of genes were found in aerobic phototrophic bacteria and in the gamma-proteobacterium Congregibacter litoralis. This may indicate that part of the reactions may be involved in a different metabolic process.
Collapse
Affiliation(s)
- Silke Friedmann
- Mikrobiologie, Institut Biologie II, Schänzlestr. 1, D-79104 Freiburg, Germany
| | | | | |
Collapse
|
26
|
Eiler A. Evidence for the ubiquity of mixotrophic bacteria in the upper ocean: implications and consequences. Appl Environ Microbiol 2006; 72:7431-7. [PMID: 17028233 PMCID: PMC1694265 DOI: 10.1128/aem.01559-06] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Alexander Eiler
- Limnology/Department of Ecology and Evolution, Evolutionary Biology Centre, Uppsala, Sweden.
| |
Collapse
|
27
|
Friedmann S, Alber BE, Fuchs G. Properties of succinyl-coenzyme A:D-citramalate coenzyme A transferase and its role in the autotrophic 3-hydroxypropionate cycle of Chloroflexus aurantiacus. J Bacteriol 2006; 188:6460-8. [PMID: 16952935 PMCID: PMC1595468 DOI: 10.1128/jb.00659-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The phototrophic bacterium Chloroflexus aurantiacus uses the 3-hydroxypropionate cycle for autotrophic CO(2) fixation. This cycle starts with acetyl-coenzyme A (CoA) and produces glyoxylate. Glyoxylate is an unconventional cell carbon precursor that needs special enzymes for assimilation. Glyoxylate is combined with propionyl-CoA to beta-methylmalyl-CoA, which is converted to citramalate. Cell extracts catalyzed the succinyl-CoA-dependent conversion of citramalate to acetyl-CoA and pyruvate, the central cell carbon precursor. This reaction is due to the combined action of enzymes that were upregulated during autotrophic growth, a coenzyme A transferase with the use of succinyl-CoA as the CoA donor and a lyase cleaving citramalyl-CoA to acetyl-CoA and pyruvate. Genomic analysis identified a gene coding for a putative coenzyme A transferase. The gene was heterologously expressed in Escherichia coli and shown to code for succinyl-CoA:d-citramalate coenzyme A transferase. This enzyme, which catalyzes the reaction d-citramalate + succinyl-CoA --> d-citramalyl-CoA + succinate, was purified and studied. It belongs to class III of the coenzyme A transferase enzyme family, with an aspartate residue in the active site. The homodimeric enzyme composed of 44-kDa subunits was specific for succinyl-CoA as a CoA donor but also accepted d-malate and itaconate instead of d-citramalate. The CoA transferase gene is part of a cluster of genes which are cotranscribed, including the gene for d-citramalyl-CoA lyase. It is proposed that the CoA transferase and the lyase catalyze the last two steps in the glyoxylate assimilation route.
Collapse
Affiliation(s)
- Silke Friedmann
- Mikrobiologie, Institut Biologie II, Schänzlestr. 1, D-79104 Freiburg, Germany
| | | | | |
Collapse
|
28
|
Frigaard NU, Bryant DA. Seeing green bacteria in a new light: genomics-enabled studies of the photosynthetic apparatus in green sulfur bacteria and filamentous anoxygenic phototrophic bacteria. Arch Microbiol 2004; 182:265-76. [PMID: 15340781 DOI: 10.1007/s00203-004-0718-9] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2004] [Revised: 07/21/2004] [Accepted: 07/22/2004] [Indexed: 10/26/2022]
Abstract
Based upon their photosynthetic nature and the presence of a unique light-harvesting antenna structure, the chlorosome, the photosynthetic green bacteria are defined as a distinctive group in the Bacteria. However, members of the two taxa that comprise this group, the green sulfur bacteria (Chlorobi) and the filamentous anoxygenic phototrophic bacteria ("Chloroflexales"), are otherwise quite different, both physiologically and phylogenetically. This review summarizes how genome sequence information facilitated studies of the biosynthesis and function of the photosynthetic apparatus and the oxidation of inorganic sulfur compounds in two model organisms that represent these taxa, Chlorobium tepidum and Chloroflexus aurantiacus. The genes involved in bacteriochlorophyll (BChl) c and carotenoid biosynthesis in these two organisms were identified by sequence homology with known BChl a and carotenoid biosynthesis enzymes, gene cluster analysis in Cfx. aurantiacus, and gene inactivation studies in Chl. tepidum. Based on these results, BChl a and BChl c biosynthesis is similar in the two organisms, whereas carotenoid biosynthesis differs significantly. In agreement with its facultative anaerobic nature, Cfx. aurantiacus in some cases apparently produces structurally different enzymes for heme and BChl biosynthesis, in which one enzyme functions under anoxic conditions and the other performs the same reaction under oxic conditions. The Chl. tepidum mutants produced with modified BChl c and carotenoid species also allow the functions of these pigments to be studied in vivo.
Collapse
Affiliation(s)
- Niels-Ulrik Frigaard
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16801, USA.
| | | |
Collapse
|
29
|
Frigaard NU, Maresca JA, Yunker CE, Jones AD, Bryant DA. Genetic manipulation of carotenoid biosynthesis in the green sulfur bacterium Chlorobium tepidum. J Bacteriol 2004; 186:5210-20. [PMID: 15292122 PMCID: PMC490927 DOI: 10.1128/jb.186.16.5210-5220.2004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2004] [Accepted: 05/14/2004] [Indexed: 11/20/2022] Open
Abstract
The green sulfur bacterium Chlorobium tepidum is a strict anaerobe and an obligate photoautotroph. On the basis of sequence similarity with known enzymes or sequence motifs, nine open reading frames encoding putative enzymes of carotenoid biosynthesis were identified in the genome sequence of C. tepidum, and all nine genes were inactivated. Analysis of the carotenoid composition in the resulting mutants allowed the genes encoding the following six enzymes to be identified: phytoene synthase (crtB/CT1386), phytoene desaturase (crtP/CT0807), zeta-carotene desaturase (crtQ/CT1414), gamma-carotene desaturase (crtU/CT0323), carotenoid 1',2'-hydratase (crtC/CT0301), and carotenoid cis-trans isomerase (crtH/CT0649). Three mutants (CT0180, CT1357, and CT1416 mutants) did not exhibit a discernible phenotype. The carotenoid biosynthetic pathway in C. tepidum is similar to that in cyanobacteria and plants by converting phytoene into lycopene using two plant-like desaturases (CrtP and CrtQ) and a plant-like cis-trans isomerase (CrtH) and thus differs from the pathway known in all other bacteria. In contrast to the situation in cyanobacteria and plants, the construction of a crtB mutant completely lacking carotenoids demonstrates that carotenoids are not essential for photosynthetic growth of green sulfur bacteria. However, the bacteriochlorophyll a contents of mutants lacking colored carotenoids (crtB, crtP, and crtQ mutants) were decreased from that of the wild type, and these mutants exhibited a significant growth rate defect under all light intensities tested. Therefore, colored carotenoids may have both structural and photoprotection roles in green sulfur bacteria. The ability to manipulate the carotenoid composition so dramatically in C. tepidum offers excellent possibilities for studying the roles of carotenoids in the light-harvesting chlorosome antenna and iron-sulfur-type (photosystem I-like) reaction center. The phylogeny of carotenogenic enzymes in green sulfur bacteria and green filamentous bacteria is also discussed.
Collapse
Affiliation(s)
- Niels-Ulrik Frigaard
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA 16802, USA.
| | | | | | | | | |
Collapse
|
30
|
Granzhan A, Penzkofer A, Hauska G. Photo-degradation of bacteriochlorophyll c in intact cells and extracts from Chlorobium tepidum. J Photochem Photobiol A Chem 2004. [DOI: 10.1016/j.jphotochem.2004.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
31
|
Herter S, Busch A, Fuchs G. L-Malyl-coenzyme A lyase/beta-methylmalyl-coenzyme A lyase from Chloroflexus aurantiacus, a bifunctional enzyme involved in autotrophic CO(2) fixation. J Bacteriol 2002; 184:5999-6006. [PMID: 12374834 PMCID: PMC135395 DOI: 10.1128/jb.184.21.5999-6006.2002] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 3-hydroxypropionate cycle is a bicyclic autotrophic CO(2) fixation pathway in the phototrophic Chloroflexus aurantiacus (Bacteria), and a similar pathway is operating in autotrophic members of the Sulfolobaceae (Archaea). The proposed pathway involves in a first cycle the conversion of acetyl-coenzyme A (acetyl-CoA) and two bicarbonates to L-malyl-CoA via 3-hydroxypropionate and propionyl-CoA; L-malyl-CoA is cleaved by L-malyl-CoA lyase into acetyl-CoA and glyoxylate. In a second cycle, glyoxylate and another molecule of propionyl-CoA (derived from acetyl-CoA and bicarbonate) are condensed by a putative beta-methylmalyl-CoA lyase to beta-methylmalyl-CoA, which is converted to acetyl-CoA and pyruvate. The putative L-malyl-CoA lyase gene of C. aurantiacus was cloned and expressed in Escherichia coli, and the recombinant enzyme was purified and studied. Beta-methylmalyl-CoA lyase was purified from cell extracts of C. aurantiacus and characterized. We show that these two enzymes are identical and that both enzymatic reactions are catalyzed by one single bifunctional enzyme, L-malyl-CoA lyase/beta-methylmalyl-CoA lyase. Interestingly, this enzyme works with two different substrates in two different directions: in the first cycle of CO(2) fixation, it cleaves L-malyl-CoA into acetyl-CoA and glyoxylate (lyase reaction), and in the second cycle it condenses glyoxylate with propionyl-CoA to beta-methylmalyl-CoA (condensation reaction). The combination of forward and reverse directions of a reversible enzymatic reaction, using two different substrates, is rather uncommon and reduces the number of enzymes required in the pathway. In summary, L-malyl-CoA lyase/beta-methylmalyl-CoA lyase catalyzes the interconversion of L-malyl-CoA plus propionyl-CoA to beta-methylmalyl-CoA plus acetyl-CoA.
Collapse
Affiliation(s)
- Sylvia Herter
- Mikrobiologie, Institut für Biologie II, Albert-Ludwigs-Universität Freiburg, Germany
| | | | | |
Collapse
|
32
|
Hügler M, Menendez C, Schägger H, Fuchs G. Malonyl-coenzyme A reductase from Chloroflexus aurantiacus, a key enzyme of the 3-hydroxypropionate cycle for autotrophic CO(2) fixation. J Bacteriol 2002; 184:2404-10. [PMID: 11948153 PMCID: PMC134993 DOI: 10.1128/jb.184.9.2404-2410.2002] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 3-hydroxypropionate cycle is a new autotrophic CO(2) fixation pathway in Chloroflexus aurantiacus and some archaebacteria. The initial step is acetyl-coenzyme A (CoA) carboxylation to malonyl-CoA by acetyl-CoA carboxylase, followed by NADPH-dependent reduction of malonyl-CoA to 3-hydroxypropionate. This reduction step was studied in Chloroflexus aurantiacus. A new enzyme was purified, malonyl-CoA reductase, which catalyzed the two-step reduction malonyl-CoA + NADPH + H(+) --> malonate semialdehyde + NADP(+) + CoA and malonate semialdehyde + NADPH + H(+) --> 3-hydroxypropionate + NADP(+). The bifunctional enzyme (aldehyde dehydrogenase and alcohol dehydrogenase) had a native molecular mass of 300 kDa and consisted of a single large subunit of 145 kDa, suggesting an alpha(2) composition. The N-terminal amino acid sequence was determined, and the incomplete gene was identified in the genome database. Obviously, the enzyme consists of an N-terminal short-chain alcohol dehydrogenase domain and a C-terminal aldehyde dehydrogenase domain. No indication of the presence of a prosthetic group was obtained; Mg(2+) and Fe(2+) stimulated and EDTA inhibited activity. The enzyme was highly specific for its substrates, with apparent K(m) values of 30 microM malonyl-CoA and 25 microM NADPH and a turnover number of 25 s(-1) subunit(-1). The specific activity in autotrophically grown cells was 0.08 micromol of malonyl-CoA reduced min(-1) (mg of protein)(-1), compared to 0.03 micromol min(-1) (mg of protein)(-1) in heterotrophically grown cells, indicating downregulation under heterotrophic conditions. Malonyl-CoA reductase is not required in any other known pathway and therefore can be taken as a characteristic enzyme of the 3-hydroxypropionate cycle. Furthermore, the enzyme may be useful for production of 3-hydroxypropionate and for a coupled spectrophotometric assay for activity screening of acetyl-CoA carboxylase, a target enzyme of potent herbicides.
Collapse
Affiliation(s)
- Michael Hügler
- Mikrobiologie, Institut für Biologie II, Albert-Ludwigs-Universität Freiburg, Freiburg, Germany
| | | | | | | |
Collapse
|
33
|
Alber BE, Fuchs G. Propionyl-coenzyme A synthase from Chloroflexus aurantiacus, a key enzyme of the 3-hydroxypropionate cycle for autotrophic CO2 fixation. J Biol Chem 2002; 277:12137-43. [PMID: 11821399 DOI: 10.1074/jbc.m110802200] [Citation(s) in RCA: 82] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The 3-hydroxypropionate cycle has been proposed as a new autotrophic CO(2) fixation pathway for the phototrophic green non-sulfur eubacterium Chloroflexus aurantiacus and for some chemotrophic archaebacteria. The cycle requires the reductive conversion of the characteristic intermediate 3-hydroxypropionate to propionyl-CoA. The specific activity of the 3-hydroxypropionate-, CoA-, K(+)-, and MgATP-dependent oxidation of NADPH in autotrophically grown cells was 0.09 micromol min(-1) mg(-1) protein, which was 2-fold down-regulated in heterotrophically grown cells. Unexpectedly, a single enzyme catalyzes the entire reaction sequence: 3-hydroxypropionate + MgATP + CoA + NADPH + H(+) --> propionyl-CoA + MgAMP + PP(i) + NADP(+) + H(2)O. The enzyme was purified 30-fold to near homogeneity and has a very large native molecular mass between 500 and 800 kDa, with subunits of about 185 kDa as judged by SDS-PAGE, suggesting a homotrimeric or homotetrameric structure. Upon incubation of this new enzyme, termed propionyl-CoA synthase, with the proteinase trypsin, the NADPH oxidation function of the enzyme was lost, whereas the enzyme still activated 3-hydroxypropionate to its CoA-thioester and dehydrated it to acrylyl-CoA. SDS-PAGE revealed that the subunits of propionyl-CoA synthase had been cleaved once and the N-terminal amino acid sequences of the two trypsin digestion products were determined. Two parts of the gene encoding propionyl-CoA synthase (pcs) were identified on two contigs of an incomplete genome data base of C. aurantiacus, and the sequence of the pcs gene was completed. Propionyl-CoA synthase is a natural fusion protein of 201 kDa consisting of a CoA ligase, an enoyl-CoA hydratase, and an enoyl-CoA reductase, the reductase domain containing the trypsin cleavage site. Similar polyfunctional large enzymes are common in secondary metabolism (e.g. polyketide synthases) but rare in primary metabolism (e.g. eukaryotic type I fatty acid synthase). These results lend strong support to the operation of the proposed pathway in autotrophic CO(2) fixation.
Collapse
Affiliation(s)
- Birgit E Alber
- Institut Biologie II, Mikrobiologie, Universität Freiburg, Schänzlestrasse 1, Freiburg D-79104, Germany.
| | | |
Collapse
|
34
|
Yakovlev AG, Taisova AS, Fetisova ZG. Light control over the size of an antenna unit building block as an efficient strategy for light harvesting in photosynthesis. FEBS Lett 2002; 512:129-32. [PMID: 11852066 DOI: 10.1016/s0014-5793(02)02238-x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
It was shown that an increase in the bacteriochlorophyll (BChl) c antenna size observed upon lowering growth light intensities led to enhancement of the hyperchromism of the BChl c Q(y) absorption band of the green photosynthetic bacterium Chloroflexus aurantiacus. With femtosecond difference absorption spectroscopy, it was shown that the amplitude of bleaching of the oligomeric BChl c Q(y) band (as compared to that for monomeric BChl a) increased with increasing BChl c content in chlorosomes. This BChl c bleaching amplitude was about doubled as the chlorosomal antenna size was about trebled. Both sets of findings clearly show that a unit BChl c aggregate in the chlorosomal antenna is variable in size and governed by the grow light intensity, thus ensuring the high efficiency of energy transfer within the BChl c antenna regardless of its size.
Collapse
Affiliation(s)
- A G Yakovlev
- A.N. Belozersky Institute of Physico-Chemical Biology, Bldg. 'A', Moscow State University, 119899, Moscow, Russia
| | | | | |
Collapse
|
35
|
Herter S, Farfsing J, Gad'On N, Rieder C, Eisenreich W, Bacher A, Fuchs G. Autotrophic CO(2) fixation by Chloroflexus aurantiacus: study of glyoxylate formation and assimilation via the 3-hydroxypropionate cycle. J Bacteriol 2001; 183:4305-16. [PMID: 11418572 PMCID: PMC95321 DOI: 10.1128/jb.183.14.4305-4316.2001] [Citation(s) in RCA: 67] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the facultative autotrophic organism Chloroflexus aurantiacus, a phototrophic green nonsulfur bacterium, the Calvin cycle does not appear to be operative in autotrophic carbon assimilation. An alternative cyclic pathway, the 3-hydroxypropionate cycle, has been proposed. In this pathway, acetyl coenzyme A (acetyl-CoA) is assumed to be converted to malate, and two CO(2) molecules are thereby fixed. Malyl-CoA is supposed to be cleaved to acetyl-CoA, the starting molecule, and glyoxylate, the carbon fixation product. Malyl-CoA cleavage is shown here to be catalyzed by malyl-CoA lyase; this enzyme activity is induced severalfold in autotrophically grown cells. Malate is converted to malyl-CoA via an inducible CoA transferase with succinyl-CoA as a CoA donor. Some enzyme activities involved in the conversion of malonyl-CoA via 3-hydroxypropionate to propionyl-CoA are also induced under autotrophic growth conditions. So far, no clue as to the first step in glyoxylate assimilation has been obtained. One possibility for the assimilation of glyoxylate involves the conversion of glyoxylate to glycine and the subsequent assimilation of glycine. However, such a pathway does not occur, as shown by labeling of whole cells with [1,2-(13)C(2)]glycine. Glycine carbon was incorporated only into glycine, serine, and compounds that contained C(1) units derived therefrom and not into other cell compounds.
Collapse
Affiliation(s)
- S Herter
- Mikrobiologie, Institut Biologie II, Universität Freiburg, Freiburg, Germany
| | | | | | | | | | | | | |
Collapse
|
36
|
van Der Meer MT, Schouten S, van Dongen BE, Rijpstra WI, Fuchs G, Damste JS, de Leeuw JW, Ward DM. Biosynthetic controls on the 13C contents of organic components in the photoautotrophic bacterium Chloroflexus aurantiacus. J Biol Chem 2001; 276:10971-6. [PMID: 11145961 DOI: 10.1074/jbc.m009701200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To assess the effects related to known and proposed biosynthetic pathways on the (13)C content of lipids and storage products of the photoautotrophic bacterium Chloroflexus aurantiacus, the isotopic compositions of bulk cell material, alkyl and isoprenoid lipids, and storage products such as glycogen and polyhydroxyalkanoic acids have been investigated. The bulk cell material was 13 per thousand depleted in (13)C relative to the dissolved inorganic carbon. Evidently, inorganic carbon fixation by the main carboxylating enzymes used by C. aurantiacus, which are assumed to use bicarbonate rather than CO(2), results in a relatively small carbon isotopic fractionation compared with CO(2) fixation by the Calvin cycle. Even carbon numbered fatty acids, odd carbon numbered fatty acids, and isoprenoid lipids were 14, 15, and 17-18 per thousand depleted in (13)C relative to the carbon source, respectively. Based on the (13)C contents of alkyl and isoprenoid lipids, a 40 per thousand difference in (13)C content between the carboxyl and methyl carbon from acetyl-coenzyme A has been calculated. Both sugars and polyhydroxyalkanoic acid were enriched in (13)C relative to the alkyl and isoprenoid lipids. To the best of our knowledge this is the first report in which the stable carbon isotopic composition of a large range of biosynthetic products in a photoautotrophic organism has been investigated and interpreted based on previously proposed inorganic carbon fixation and biosynthetic pathways. Our results indicate that compound-specific stable carbon isotope analysis may provide a rapid screening tool for carbon fixation pathways.
Collapse
Affiliation(s)
- M T van Der Meer
- Netherlands Institute for Sea Research (NIOZ), Department of Marine Biogeochemistry and Toxicology, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands
| | | | | | | | | | | | | | | |
Collapse
|
37
|
Tokita S, Frigaard NU, Hirota M, Shimada K, Matsuura K. Quenching of bacteriochlorophyll fluorescence in chlorosomes from Chloroflexus aurantiacus by exogenous quinones. Photochem Photobiol 2000; 72:345-50. [PMID: 10989605 DOI: 10.1562/0031-8655(2000)072<0345:qobfic>2.0.co;2] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The quenching of bacteriochlorophyll (BChl) c fluorescence in chlorosomes isolated from Chloroflexus aurantiacus was examined by the addition of various benzoquinones, naphthoquinones (NQ), and anthraquinones (AQ). Many quinones showed strong quenching in the micromolar or submicromolar range. The number of quinone molecules bound to the chlorosomes was estimated to be as small as one quinone molecule per 50 BChl c molecules. Quinones which exhibit a high quenching effect have sufficient hydrophobicity and one or more hydroxyl groups in the alpha positions of NQ and AQ. Chlorobiumquinone has been suggested to be essential for the endogenous quenching of chlorosome fluorescence in Chlorobium tepidum under oxic conditions. We suggest that the quenching effect of chlorobiumquinone in chlorosomes from Chl. tepidum is related to the 1'-oxo group neighboring the dicarbonyl group.
Collapse
Affiliation(s)
- S Tokita
- Department of Biology, Tokyo Metropolitan University, Japan.
| | | | | | | | | |
Collapse
|
38
|
van der Meer MT, Schouten S, de Leeuw JW, Ward DM. Autotrophy of green non-sulphur bacteria in hot spring microbial mats: biological explanations for isotopically heavy organic carbon in the geological record. Environ Microbiol 2000; 2:428-35. [PMID: 11234931 DOI: 10.1046/j.1462-2920.2000.00124.x] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Inferences about the evidence of life recorded in organic compounds within the Earth's ancient rocks have depended on 13C contents low enough to be characteristic of biological debris produced by the well-known CO2 fixation pathway, the Calvin cycle. 'Atypically' high values have been attributed to isotopic alteration of sedimentary organic carbon by thermal metamorphism. We examined the possibility that organic carbon characterized by a relatively high 13C content could have arisen biologically from recently discovered autotrophic pathways. We focused on the green non-sulphur bacterium Chloroflexus aurantiacus that uses the 3-hydroxypropionate pathway for inorganic carbon fixation and is geologically significant as it forms modern mat communities analogous to stromatolites. Organic matter in mats constructed by Chloroflexus spp. alone had relatively high 13C contents (-14.9%) and lipids diagnostic of Chloroflexus that were also isotopically heavy (-8.9% to -18.5%). Organic matter in mats constructed by Chloroflexus in conjunction with cyanobacteria had a more typical Calvin cycle signature (-23.5%). However, lipids diagnostic of Chloroflexus were isotopically enriched (-15.1% to -24.1%) relative to lipids typical of cyanobacteria (-33.9% to -36.3%). This suggests that, in mats formed by both cyanobacteria and Chloroflexus, autotrophy must have a greater effect on Chloroflexus carbon metabolism than the photoheterotrophic consumption of cyanobacterial photosynthate. Chloroflexus cell components were also selectively preserved. Hence, Chloroflexus autotrophy and selective preservation of its products constitute one purely biological mechanism by which isotopically heavy organic carbon could have been introduced into important Precambrian geological features.
Collapse
Affiliation(s)
- M T van der Meer
- Netherlands Institute for Sea Research, Department of Marine Biogeochemistry and Toxicology, Texel.
| | | | | | | |
Collapse
|
39
|
Wang ZY, Umetsu M, Kobayashi M, Nozawa T. Complete Assignment of 1H NMR Spectra and Structural Analysis of Intact Bacteriochlorophyll c Dimer in Solution. J Phys Chem B 1999. [DOI: 10.1021/jp984483t] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Zheng-Yu Wang
- Department of Biomolecular Engineering, Faculty of Engineering, Center for Interdisciplinary Science, Tohoku University, Sendai 980-8579, Japan
| | - Mitsuo Umetsu
- Department of Biomolecular Engineering, Faculty of Engineering, Center for Interdisciplinary Science, Tohoku University, Sendai 980-8579, Japan
| | - Masayuki Kobayashi
- Department of Biomolecular Engineering, Faculty of Engineering, Center for Interdisciplinary Science, Tohoku University, Sendai 980-8579, Japan
| | - Tsunenori Nozawa
- Department of Biomolecular Engineering, Faculty of Engineering, Center for Interdisciplinary Science, Tohoku University, Sendai 980-8579, Japan
| |
Collapse
|
40
|
Oba T, Tamiaki H. Molecular Requirement of Chlorosomal Chlorophylls. Self-Organization of a Chlorophyll Derivative Possessing a Hydroxyl Group at Ring II. Photochem Photobiol 1998. [DOI: 10.1111/j.1751-1097.1998.tb05202.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
41
|
Wang ZY, Marx G, Umetsu M, Kobayashi M, Mimuro M, Nozawa T. Morphology and spectroscopy of chlorosomes from Chlorobium tepidum by alcohol treatments. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1995. [DOI: 10.1016/0005-2728(95)00113-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
42
|
Smith KM. Nomenclature of the bacteriochlorophyllsc,d, ande. PHOTOSYNTHESIS RESEARCH 1994; 41:23-26. [PMID: 24310009 DOI: 10.1007/bf02184141] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/1993] [Accepted: 12/20/1993] [Indexed: 06/02/2023]
Abstract
A system for nomenclature of the various homologues of the bacteriochlorophyllsc(1),d(2), ande(3) is presented.
Collapse
Affiliation(s)
- K M Smith
- Department of Chemistry, University of California, 95616, Davis, CA, USA
| |
Collapse
|
43
|
Foidl M, Golecki JR, Oelze J. Bacteriochlorophyllc formation and chlorosome development inChloroflexus aurantiacus. PHOTOSYNTHESIS RESEARCH 1994; 41:145-150. [PMID: 24310020 DOI: 10.1007/bf02184154] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/1993] [Accepted: 02/08/1994] [Indexed: 06/02/2023]
Abstract
The dependence of chlorosome development on bacteriochlorophyll (BChl)c synthesis was studied with the phototrophic green bacteriumChloroflexus aurantiacus. By selecting defined culture conditions, three possibilities could be identified. Upon addition of 5-aminolevulinic acid, cells of resting cultures increased their specific BChlc contents as well as the volumes of already existing chlorosomes. The number of chlorosomes, however, remained constant. Serine-limited chemostat cultures grown under steady state conditions exhibited constant rates of synthesis of both BChlc as well as of chlorosomes. The volume of the latter remained constant, as well. Upon addition of ALA to chemostat cultures, chlorosomes were synthesized at the same rate as before but their volumes increased as a consequence of increased BChlc incorporation. In chlorosomes isolated from resting cultures supplied with ALA the amounts of all of the polypeptides increased only slightly, if at all. Moreover, the ratio of all of the chlorosomal polypeptides remained largely constant. These results show that chlorosomes may incorporate newly synthesized BChlc without concomitant formation of chlorosomal polypeptides. This means that there was no obvious coordination of polypeptide and BChlc synthesis. On this basis, it appears unlikely that one of the chlorosomal polypeptides functions as an apoprotein of a presumed BChlc holochrome complex.
Collapse
Affiliation(s)
- M Foidl
- Institut für Biologie II (Mikrobiologie), Universität Freiburg, Schänzlestraße 1, D-79104, Freiburg, Germany
| | | | | |
Collapse
|
44
|
Pierson BK. Reflections onChloroflexus. PHOTOSYNTHESIS RESEARCH 1994; 41:7-15. [PMID: 24310007 DOI: 10.1007/bf02184139] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/1994] [Accepted: 02/23/1994] [Indexed: 06/02/2023]
Abstract
A personal historic account is presented of the discovery of the anoxygenic filamentous bacteria of hot springs:Heliothrix oregonensis andChloroflexus aurantiacus. The later discoveries of marine and hypersaline forms are also described.
Collapse
Affiliation(s)
- B K Pierson
- Biology Department, University of Puget Sound, 98416, Tacoma, WA, USA
| |
Collapse
|
45
|
Lehmann RP, Brunisholz RA, Zuber H. Structural differences in chlorosomes from Chloroflexus aurantiacus grown under different conditions support the BChl c-binding function of the 5.7 kDa polypeptide. FEBS Lett 1994; 342:319-24. [PMID: 8150092 DOI: 10.1016/0014-5793(94)80524-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Structurally different chlorosomes were isolated from the green photosynthetic bacterium Chloroflexus aurantiacus grown under different conditions. They were analysed with respect to variable pigment-protein stoichiometries in view of the presumed BChl c-binding function of the 5.7 kDa chlorosome polypeptide. Under high-light conditions on substrate-limited growth medium the pigment-protein ratio of isolated chlorosomes was several times lower than under low-light conditions on complex medium. Proteolytic degradation of the 5.7 kDa polypeptide in high-light chlorosomes led to a 60% decrease of the absorbance at 740 nm. The CD spectrum of high-light chlorosomes exhibited a sixfold lower relative intensity at 740 nm (delta A/A740) than low-light chlorosomes, but it showed a fivefold increase in intensity upon degradation of the 5.7 kDa polypeptide compared to a twofold increase in low-light chlorosomes. It seems probable that BChl c in the chlorosomes is present as oligomers bound to the 5.7 kDa polypeptide. Our data suggest further that compared to low-light chlorosomes smaller oligomers or single BChl c molecules are bound to the 5.7 kDa polypeptide in high-light chlorosomes resulting in lower rotational strength.
Collapse
Affiliation(s)
- R P Lehmann
- Institut für Molekularbiologie und Biophysik, ETH-Hönggerberg, Zürich, Switzerland
| | | | | |
Collapse
|
46
|
Niedermeier G, Shiozawa JA, Lottspeich F, Feick RG. The primary structure of two chlorosome proteins from Chloroflexus aurantiacus. FEBS Lett 1994; 342:61-5. [PMID: 7511541 DOI: 10.1016/0014-5793(94)80585-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The complete nucleotide sequence of two chlorosome proteins with apparent molecular weights of M(r) 18,000 and M(r) 11,000 from Chloroflexus aurantiacus have been determined. The two polypeptides were 145 and 97 amino acids long and possessed true molecular masses of 15,545 and 10,820 Da, respectively. Protein chemical sequencing was done in parallel to confirm the primary structure deduced from nucleotide sequencing. By Northern blot analysis of RNA isolated from phototrophically grown cells a transcript of 0.95 kb was detected which is the expected length for a mRNA encoding both genes.
Collapse
Affiliation(s)
- G Niedermeier
- Max-Planck-Institut für Biochemie, Martinsried, Germany
| | | | | | | |
Collapse
|
47
|
Mimuro M, Nozawa T, Tamai N, Nishimura Y, Yamazaki I. Presence and significance of minor antenna components in the energy transfer sequence of the green photosynthetic bacterium Chloroflexus aurantiacus. FEBS Lett 1994; 340:167-72. [PMID: 8131839 DOI: 10.1016/0014-5793(94)80130-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Antenna components in the energy transfer processes of a green photosynthetic bacterium Chloroflexus aurantiacus were spectrally investigated by time-resolved fluorescence spectroscopy at -196 degrees C on intact cells. Besides major antenna components so far reported, three minor components were resolved; those were Bchl c located at 785 nm, the baseplate Bchl a at 819 nm and Bchl a in the B808-866 complex at 910 nm. The last component was assigned to a longer wavelength antenna closely associated with a reaction center. An additional Bchl c fluorescence component was kinetically suggested to be present, which can be an energy donor to a major Bchl c. Presence of these minor components was signified in terms of (1) increase in the spectral overlap integral and (2) adjustment of the direction of dipole moments in the energy transfer sequence of intact cells.
Collapse
Affiliation(s)
- M Mimuro
- National Institute for Basic Biology, Aichi, Japan
| | | | | | | | | |
Collapse
|
48
|
Abstract
Conditions are described that support anaerobic dark chemotrophic growth of heliobacteria. Growth was pyruvate-dependent and was best in well-buffered pyruvate media supplemented with yeast extract. Heliobacterial cells grown in darkness synthesized bacteriochlorophyll g and carotenoids and fermented pyruvate to acidic products, CO2, and in some cases, H2. All recognized species of heliobacteria as well as several newly isolated strains were capable of dark anaerobic growth, suggesting that this growth mode may be ecologically important for survival of these organisms in their soil habitat.
Collapse
Affiliation(s)
- L K Kimble
- Department of Microbiology, Southern Illinois University, Carbondale 62901
| | | | | |
Collapse
|
49
|
Influence of vitamin B12 and light on the formation of chlorosomes in green- and brown-colored Chlorobium species. Arch Microbiol 1993. [DOI: 10.1007/bf00249124] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
50
|
Seitz AP, Nielsen TH, Overmann JÃ. Physiology of purple sulfur bacteria forming macroscopic aggregates in Great Sippewissett Salt Marsh, Massachusetts. FEMS Microbiol Ecol 1993. [DOI: 10.1111/j.1574-6941.1993.tb00035.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
|