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Hirose M, Tsukatani Y, Harada J, Tamiaki H. In vitro reversible dehydration in C3-substituents of zinc chlorophyll analogs by BchF and BchV enzymes: Stereoselectivity and substrate specificity in the dehydration. BIOCHIMICA ET BIOPHYSICA ACTA. BIOENERGETICS 2023; 1864:148959. [PMID: 36822492 DOI: 10.1016/j.bbabio.2023.148959] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 02/25/2023]
Abstract
In the biosynthetic pathway of bacteriochlorophyll(BChl)-a/b/c/d/e molecules, BchF and BchV enzymes catalyze the hydration of a C3-vinyl to C3-1-hydroxyethyl group. In this study, the in vitro reactions catalyzed by BchF and BchV partially afforded a C31-epimeric mixture of the hydrated products (secondary alcohols), with the primary recovery of the C3-vinylated substrate. The stereoselectivity and substrate specificity for the in vitro reverse enzymatic dehydration were examined using zinc chlorophyll analogs as model substrates by BchF and BchV, which were obtained from extracts of Escherichia coli overexpressing the respective genes from Chlorobaculum tepidum and used without further purification. Both BchF and BchV preferred dehydration of the (31R)-epimers over the (31S)-epimers. The (31R)-epimer was directly dehydrated by BchF and BchV to give the C3-vinylated product. By contrast, two reaction pathways for BchF and BchV dehydrations of the (31S)-epimer were proposed: (1) the (31S)-epimer would be directly dehydrated to C3-vinyl group. (2) the (31S)-epimer would be epimerized to the (31R)-epimer, and the resulting epimer was dehydrated. The results indicated that both BchF and BchV did function as a hydratase/dehydratase and could play a role in the C31-epimerization. An increase in the alkyl size at the C8-position gradually suppressed the BchF and BchV-catalyzed dehydration in vitro, while the C121- and C20-methylation only slightly affected the reaction. Using the BchF dehydration, a large amount of 3-vinyl-bacteriochlorophyllide-a was successfully prepared, with the retention of the chemically labile, central magnesium atom.
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Affiliation(s)
- Mitsuaki Hirose
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Yusuke Tsukatani
- Institute for Extra-cutting-edge Science and Technology Avant-garde Research (X-star), Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Kanagawa 237-0061, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Fukuoka 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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Proteomic Time-Course Analysis of the Filamentous Anoxygenic Phototrophic Bacterium, Chloroflexus aurantiacus, during the Transition from Respiration to Phototrophy. Microorganisms 2022; 10:microorganisms10071288. [PMID: 35889008 PMCID: PMC9316378 DOI: 10.3390/microorganisms10071288] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 02/05/2023] Open
Abstract
Chloroflexus aurantiacus is a filamentous anoxygenic phototrophic bacterium that grows chemotrophically under oxic conditions and phototrophically under anoxic conditions. Because photosynthesis-related genes are scattered without any gene clusters in the genome, it is still unclear how this bacterium regulates protein expression in response to environmental changes. In this study, we performed a proteomic time-course analysis of how C. aurantiacus expresses proteins to acclimate to environmental changes, namely the transition from chemoheterotrophic respiratory to photoheterotrophic growth mode. Proteomic analysis detected a total of 2520 proteins out of 3934 coding sequences in the C. aurantiacus genome from samples collected at 13 time points. Almost all proteins for reaction centers, light-harvesting chlorosomes, and carbon fixation pathways were successfully detected during the growing phases in which optical densities and relative bacteriochlorophyll c contents increased simultaneously. Combination of proteomics and pigment analysis suggests that the self-aggregation of bacteriochlorophyllide c could precede the esterification of the hydrophobic farnesyl tail in cells. Cytoplasmic subunits of alternative complex III were interchanged between oxic and anoxic conditions, although membrane-bound subunits were used for both conditions. These data highlight the protein expression dynamics of phototrophy-related genes during the transition from respiration to phototrophy.
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Hirose M, Harada J, Tamiaki H. Detection of 13 2-carboxy-chlorin produced by the in vitro BciC enzymatic hydrolysis of zinc chlorophyllide. Bioorg Med Chem Lett 2021; 40:127931. [PMID: 33705911 DOI: 10.1016/j.bmcl.2021.127931] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 02/23/2021] [Accepted: 02/25/2021] [Indexed: 10/22/2022]
Abstract
Green photosynthetic bacteria with an efficient light-harvesting system contain special chlorophyll molecules, called bacteriochlorophylls c, d, e, in their main antennae. In the biosynthetic pathway, a BciC enzyme is proposed to catalyze the hydrolysis of the C132-methoxycarbonyl group of chlorophyllide a, but the resulting C132-carboxy group has not been detected yet because it is spontaneously removed due to the instability of the β-keto-carboxylic acid. In this study, the in vitro BciC enzymatic reactions of zinc methyl (131R/S)-hydroxy-mesochlorophyllides a were examined and a carboxylic acid possessing the C132S-OH was first observed as the hydrolyzed product of the C132-COOCH3.
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Affiliation(s)
- Mitsuaki Hirose
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Jiro Harada
- Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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Hirose M, Harada J, Tamiaki H. In Vitro Hydrolysis of Zinc Chlorophyllide a Homologues by a BciC Enzyme. Biochemistry 2020; 59:4622-4626. [PMID: 33258578 DOI: 10.1021/acs.biochem.0c00850] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Chlorosomes in green photosynthetic bacteria are the largest and most efficient light-harvesting antenna systems of all phototrophs. The core part of chlorosomes consists of bacteriochlorophyll c, d, or e molecules. In their biosynthetic pathway, a BciC enzyme catalyzes the removal of the C132-methoxycarbonyl group of chlorophyllide a. In this study, the in vitro enzymatic reactions of chlorophyllide a analogues, C132-methylene- and ethylene-inserted zinc complexes, were examined using a BciC protein from Chlorobaculum tepidum. As the products, their hydrolyzed free carboxylic acids were observed without the corresponding demethoxycarbonylated compounds. The results showed that the in vivo demethoxycarbonylation of chlorophyllide a by an action of the BciC enzyme would occur via two steps: (1) an enzymatic hydrolysis of a methyl ester at the C132-position, followed by (2) a spontaneous (nonenzymatic) decarboxylation in the resulting carboxylic acid.
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Affiliation(s)
- Mitsuaki Hirose
- Graduated School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduated School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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Hirose M, Teramura M, Harada J, Ogasawara S, Tamiaki H. In vitro C13 2-dealkoxycarbonylations of zinc chlorophyll a derivatives including C13 2-substitutes by a BciC enzyme. Bioorg Chem 2020; 102:104111. [PMID: 32738567 DOI: 10.1016/j.bioorg.2020.104111] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 07/16/2020] [Accepted: 07/17/2020] [Indexed: 01/20/2023]
Abstract
Chlorosomes in the green photosynthetic bacteria are the largest and most efficient light-harvesting antenna systems of all phototrophs. The core part of chlorosomes consists of bacteriochlorophyll c, d, e, or f molecules. In their biosynthetic pathway, a BciC enzyme catalyzes the removal of the C132-methoxycarbonyl group of chlorophyllide a. In this study, in vitro C132-dealkoxycarbonylations of zinc chlorophyll a derivatives bearing a methyl-, ethyl- or propyl-esterifying group and its methyl ester analogs with additional alkyl and hydroxy groups at the C132-position were examined using the BciC enzyme. The BciC-catalyzed reaction activity for the C132-methoxycarbonylated substrate was comparable to that for the ethoxycarbonylated compound; however, depropoxycarbonylation did not proceed. The BciC enzymatic demethoxycarbonylation of zinc methyl C132-alkylated pheophorbides a was gradually suppressed with the elongation of the alkyl chain and finally became inactive for the propyl substrate. The reaction of the C132-hydroxylated substrate (allomer) was accelerated compared to that of the C132-methyl analog possessing a similar steric size, and gave the corresponding C132-oxo product via further air-oxidation. All of the abovementioned enzymatic reactions occurred for one of the C132-epimers with the same configuration as in chlorophyllide a. The above substrate specificities and product distributions indicated the stereochemistry and size of the BciC enzymatic active site (pocket).
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Affiliation(s)
- Mitsuaki Hirose
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Jiro Harada
- Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka 830-0011, Japan
| | - Shin Ogasawara
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan.
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Abstract
Modified tetrapyrroles are large macrocyclic compounds, consisting of diverse conjugation and metal chelation systems and imparting an array of colors to the biological structures that contain them. Tetrapyrroles represent some of the most complex small molecules synthesized by cells and are involved in many essential processes that are fundamental to life on Earth, including photosynthesis, respiration, and catalysis. These molecules are all derived from a common template through a series of enzyme-mediated transformations that alter the oxidation state of the macrocycle and also modify its size, its side-chain composition, and the nature of the centrally chelated metal ion. The different modified tetrapyrroles include chlorophylls, hemes, siroheme, corrins (including vitamin B12), coenzyme F430, heme d1, and bilins. After nearly a century of study, almost all of the more than 90 different enzymes that synthesize this family of compounds are now known, and expression of reconstructed operons in heterologous hosts has confirmed that most pathways are complete. Aside from the highly diverse nature of the chemical reactions catalyzed, an interesting aspect of comparative biochemistry is to see how different enzymes and even entire pathways have evolved to perform alternative chemical reactions to produce the same end products in the presence and absence of oxygen. Although there is still much to learn, our current understanding of tetrapyrrole biogenesis represents a remarkable biochemical milestone that is summarized in this review.
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Affiliation(s)
- Donald A Bryant
- Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, Pennsylvania 16802
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
| | - C Neil Hunter
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Martin J Warren
- School of Biosciences, University of Kent, Canterbury CT2 7NJ, United Kingdom
- Quadram Institute Bioscience, Norwich Research Park, Norwich NR4 7UQ, United Kingdom
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Hirose M, Teramura M, Harada J, Tamiaki H. BciC-Catalyzed C13 2 -Demethoxycarbonylation of Metal Pheophorbide a Alkyl Esters. Chembiochem 2020; 21:1473-1480. [PMID: 31900999 DOI: 10.1002/cbic.201900745] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Indexed: 11/10/2022]
Abstract
Bacteriochlorophyll c molecules self-aggregate to form large oligomers in the core part of chlorosomes, which are the main light-harvesting antenna systems of green photosynthetic bacteria. In the biosynthetic pathway of bacteriochlorophyll c, a BciC enzyme catalyzes the removal of the C132 -methoxycarbonyl group of chlorophyllide a, which possesses a free propionate residue at the C17-position and a magnesium ion as the central metal. The in vitro C132 -demethoxycarbonylations of chlorophyll a derivatives with various alkyl propionate residues and central metals were examined by using the BciC enzyme derived from one green sulfur bacteria species, Chlorobaculum tepidum. The BciC enzymatic reactions of zinc pheophorbide a alkyl esters were gradually suppressed with an increase of the alkyl chain length in the C17-propionate residue (from methyl to pentyl esters) and finally the hexyl ester became inactive for the BciC reaction. Although not only the zinc but also nickel and copper complexes were demethoxycarbonylated by the BciC enzyme, the reactions were largely dependent on the coordination ability of the central metals: Zn>Ni>Cu. The above substrate specificity indicates that the BciC enzyme would not bind directly to the carboxy group of chlorophyllide a, but would bind to its central magnesium to form the stereospecific complex of BciC with chlorophyllide a, giving pyrochlorophyllide a, which lacks the (132 R)-methoxycarbonyl group.
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Affiliation(s)
- Mitsuaki Hirose
- Graduated School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Misato Teramura
- Graduated School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Jiro Harada
- Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduated School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
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Teramura M, Harada J, Tamiaki H. In vitro demethoxycarbonylation of various chlorophyll analogs by a BciC enzyme. PHOTOSYNTHESIS RESEARCH 2019; 139:163-171. [PMID: 30182280 DOI: 10.1007/s11120-018-0573-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2018] [Accepted: 08/11/2018] [Indexed: 06/08/2023]
Abstract
Unique light-harvesting antennas in the green sulfur bacterium Chlorobaculum tepidum, called chlorosomes, consist of self-aggregates of bacteriochlorophyll (BChl) c. In the biosynthesis of BChl c, BciC demethoxycarbonylase removes the C132-methoxycarbonyl group to facilitate the self-aggregation of BChl c. We previously reported the in vitro BciC-enzymatic reactions and discussed the function of this enzyme in the biosynthesis of BChl c. This study aims to examine the substrate specificity of BciC in detail using several semi-synthetic (bacterio)chlorophyll derivatives. The results indicate that the substrate specificity of BciC is measurably affected by structural changes on the A/B rings including the bacteriochlorin π-systems. Moreover, BciC showed its activity on a Zn-chelated chlorophyll derivative. On the contrary, BciC recognized structural modifications on the D/E rings, including porphyrin pigments, which resulted in the significant decrease in the enzymatic activity. The utilization of BciC provides mild conditions that may be useful for the in vitro preparation of various chemically (un)stable chlorophyllous pigments.
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Affiliation(s)
- Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
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Teramura M, Tamiaki H. Semi-synthesis and HPLC analysis of (bacterio)chlorophyllides possessing a propionic acid residue at the C17-position. J PORPHYR PHTHALOCYA 2018. [DOI: 10.1142/s1088424618500347] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Various chlorophyll and bacteriochlorophyll derivatives possessing a magnesium or zinc atom at the central position and a free carboxylic acid group at the C17[Formula: see text]-position, also known as (bacterio)chlorophyllides, were synthesized through a combination of organic synthesis techniques and enzymatic steps. The semi-synthetic (bacterio)chlorophyllides were purified and analyzed using reversed-phase high-performance liquid chromatography with UV-vis spectroscopy and mass spectrometry. These free propionic acid-containing chlorophyllous pigments can be useful research materials for the study of (bacterio)chlorophyll metabolisms.
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Affiliation(s)
- Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga 525-8577, Japan
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Thweatt JL, Ferlez BH, Golbeck JH, Bryant DA. BciD Is a Radical S-Adenosyl-l-methionine (SAM) Enzyme That Completes Bacteriochlorophyllide e Biosynthesis by Oxidizing a Methyl Group into a Formyl Group at C-7. J Biol Chem 2016; 292:1361-1373. [PMID: 27994052 DOI: 10.1074/jbc.m116.767665] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Revised: 12/12/2016] [Indexed: 01/05/2023] Open
Abstract
Green bacteria are chlorophotorophs that synthesize bacteriochlorophyll (BChl) c, d, or e, which assemble into supramolecular, nanotubular structures in large light-harvesting structures called chlorosomes. The biosynthetic pathways of these chlorophylls are known except for one reaction. Null mutants of bciD, which encodes a putative radical S-adenosyl-l-methionine (SAM) protein, are unable to synthesize BChl e but accumulate BChl c; however, it is unknown whether BciD is sufficient to convert BChl c (or its precursor, bacteriochlorophyllide (BChlide) c) into BChl e (or BChlide e). To determine the function of BciD, we expressed the bciD gene of Chlorobaculum limnaeum strain DSMZ 1677T in Escherichia coli and purified the enzyme under anoxic conditions. Electron paramagnetic resonance spectroscopy of BciD indicated that it contains a single [4Fe-4S] cluster. In assays containing SAM, BChlide c or d, and sodium dithionite, BciD catalyzed the conversion of SAM into 5'-deoxyadenosine and BChlide c or d into BChlide e or f, respectively. Our analyses also identified intermediates that are proposed to be 71-OH-BChlide c and d Thus, BciD is a radical SAM enzyme that converts the methyl group of BChlide c or d into the formyl group of BChlide e or f This probably occurs by a mechanism involving consecutive hydroxylation reactions of the C-7 methyl group to form a geminal diol intermediate, which spontaneously dehydrates to produce the final products, BChlide e or BChlide f The demonstration that BciD is sufficient to catalyze the conversion of BChlide c into BChlide e completes the biosynthetic pathways for all "Chlorobium chlorophylls."
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Affiliation(s)
| | - Bryan H Ferlez
- From the Departments of Biochemistry and Molecular Biology and
| | - John H Golbeck
- From the Departments of Biochemistry and Molecular Biology and.,Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802 and
| | - Donald A Bryant
- From the Departments of Biochemistry and Molecular Biology and .,the Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717
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Teramura M, Harada J, Tamiaki H. In vitro stereospecific hydration activities of the 3-vinyl group of chlorophyll derivatives by BchF and BchV enzymes involved in bacteriochlorophyll c biosynthesis of green sulfur bacteria. PHOTOSYNTHESIS RESEARCH 2016; 130:33-45. [PMID: 26816140 DOI: 10.1007/s11120-016-0220-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/11/2015] [Accepted: 01/11/2016] [Indexed: 06/05/2023]
Abstract
The photosynthetic green sulfur bacterium Chlorobaculum (Cba.) tepidum produces bacteriochlorophyll (BChl) c pigments bearing a chiral 1-hydroxyethyl group at the 3-position, which self-aggregate to construct main light-harvesting antenna complexes, chlorosomes. The secondary alcoholic hydroxy group is requisite for chlorosomal aggregation and biosynthesized by hydrating the 3-vinyl group of their precursors. Using recombinant proteins of Cba. tepidum BchF and BchV, we examined in vitro enzymatic hydration of some 3-vinyl-chlorophyll derivatives. Both the enzymes catalyzed stereoselective hydration of zinc 3-vinyl-8-ethyl-12-methyl-bacteriopheophorbide c or d to the zinc 31 R-bacteriopheophorbide c or d homolog, respectively, with a slight amount of the 31 S-epimric species. A similar R-stereoselectivity was observed in the BchF-hydration of zinc 3-vinyl-8-ethyl- and propyl-12-ethyl-bacteriopheophorbides c, while their BchV-hydration gave a relatively larger amount of the 31 S-epimers. The in vitro stereoselective hydration confirmed the in vivo production of the S-epimeric species by BchV. The enzymatic hydration for the above 8-propylated substrate proceeded more slowly than that for the 8-ethylated, and the 8-isobutylated substrate was no longer hydrated. Based on these results, biosynthetic pathways of BChl c homologs and epimers are proposed.
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Affiliation(s)
- Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan.
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Teramura M, Harada J, Mizoguchi T, Yamamoto K, Tamiaki H. In Vitro Assays of BciC Showing C132-Demethoxycarbonylase Activity Requisite for Biosynthesis of Chlorosomal Chlorophyll Pigments. PLANT & CELL PHYSIOLOGY 2016; 57:1048-1057. [PMID: 26936794 DOI: 10.1093/pcp/pcw045] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Accepted: 02/24/2016] [Indexed: 06/05/2023]
Abstract
A BciC enzyme is related to the removal of the C13(2)-methoxycarbonyl group in biosynthesis of bacteriochlorophylls (BChls) 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 C13(2)-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 diverting the chlorosomal pigment biosynthetic pathway at the stage of Chlide a away from syntheses of other pigments such as BChl a and Chl 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.
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Affiliation(s)
- Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577 Japan
| | - Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011 Japan
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577 Japan
| | - Ken Yamamoto
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011 Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577 Japan
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Harada J, Teramura M, Mizoguchi T, Tsukatani Y, Yamamoto K, Tamiaki H. Stereochemical conversion of C3-vinyl group to 1-hydroxyethyl group in bacteriochlorophyll c by the hydratases BchF and BchV: adaptation of green sulfur bacteria to limited-light environments. Mol Microbiol 2015; 98:1184-98. [PMID: 26331578 DOI: 10.1111/mmi.13208] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/28/2015] [Indexed: 11/28/2022]
Abstract
Photosynthetic green sulfur bacteria inhabit anaerobic environments with very low-light conditions. To adapt to such environments, these bacteria have evolved efficient light-harvesting antenna complexes called as chlorosomes, which comprise self-aggregated bacteriochlorophyll c in the model green sulfur, bacterium Chlorobaculum tepidum. The pigment possess a hydroxy group at the C3(1) position that produces a chiral center with R- or S-stereochemistry and the C3(1) -hydroxy group serves as a connecting moiety for the self-aggregation. Chlorobaculum tepidum carries the two possible homologous genes for C3-vinyl hydratase, bchF and bchV. In the present study, we constructed deletion mutants of each of these genes. Pigment analyses of the bchF-inactivated mutant, which still has BchV as a sole hydratase, showed higher ratios of S-epimeric bacteriochlorophyll c than the wild-type strain. The heightened prevalence of S-stereoisomers in the mutant was more remarkable at lower light intensities and caused a red shift of the chlorosomal Qy absorption band leading to advantages for light-energy transfer. In contrast, the bchV-mutant possessing only BchF showed a significant decrease of the S-epimers and accumulations of C3-vinyl BChl c species. As trans- criptional level of bchV was upregulated at lower light intensity, the Chlorobaculum tepidum adapted to low-light environments by control of the bchV transcription.
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Affiliation(s)
- Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Misato Teramura
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
| | - Yusuke Tsukatani
- Earth-Life Science Institute, Tokyo Institute of Technology, Meguro, Tokyo, 152-8550, Japan.,PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama, 332-0012, Japan
| | - Ken Yamamoto
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, 525-8577, Japan
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Lange C, Kiesel S, Peters S, Virus S, Scheer H, Jahn D, Moser J. Broadened Substrate Specificity of 3-Hydroxyethyl Bacteriochlorophyllide a Dehydrogenase (BchC) Indicates a New Route for the Biosynthesis of Bacteriochlorophyll a. J Biol Chem 2015; 290:19697-709. [PMID: 26088139 PMCID: PMC4528133 DOI: 10.1074/jbc.m115.660555] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Revised: 06/18/2015] [Indexed: 11/06/2022] Open
Abstract
Bacteriochlorophyll a biosynthesis requires formation of a 3-hydroxyethyl group on pyrrole ring A that gets subsequently converted into a 3-acetyl group by 3-vinyl bacteriochlorophyllide a hydratase (BchF) followed by 3-hydroxyethyl bacteriochlorophyllide a dehydrogenase (BchC). Heterologous overproduction of Chlorobaculum tepidum BchF revealed an integral transmembrane protein that was efficiently isolated by detergent solubilization. Recombinant C. tepidum BchC was purified as a soluble protein-NAD(+) complex. Substrate recognition of BchC was investigated using six artificial substrate molecules. Modification of the isocyclic E ring, omission of the central magnesium ion, zinc as an alternative metal ion, and a non-reduced B ring system were tolerated by BchC. According to this broadened in vitro activity, the chlorin 3-hydroxyethyl chlorophyllide a was newly identified as a natural substrate of BchC in a reconstituted pathway consisting of dark-operative protochlorophyllide oxidoreductase, BchF, and BchC. The established reaction sequence would allow for an additional new branching point for the synthesis of bacteriochlorophyll a. Biochemical and site-directed mutagenesis analyses revealed, in contrast to theoretical predictions, a zinc-independent BchC catalysis that requires NAD(+) as a cofactor. Based on these results, we are designating a new medium-chain dehydrogenase/reductase family (MDR057 BchC) as theoretically proposed from a recent bioinformatics analysis.
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Affiliation(s)
- Christiane Lange
- From the Institute of Microbiology, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany and
| | - Svenja Kiesel
- From the Institute of Microbiology, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany and
| | - Sabine Peters
- From the Institute of Microbiology, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany and
| | - Simone Virus
- From the Institute of Microbiology, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany and
| | - Hugo Scheer
- Department Biology I, Botany, Ludwig-Maximilians-Universität München, Menzingerstrasse 67, D-80638 München, Germany
| | - Dieter Jahn
- From the Institute of Microbiology, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany and
| | - Jürgen Moser
- From the Institute of Microbiology, Technische Universität Braunschweig, Spielmannstrasse 7, D-38106 Braunschweig, Germany and
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Harada J, Mizoguchi T, Nomura K, Tamiaki H. Isolation and structural determination of C8-vinyl-bacteriochlorophyll d from the bciA and bchU double mutant of the green sulfur bacterium Chlorobaculum tepidum. PHOTOSYNTHESIS RESEARCH 2014; 121:13-23. [PMID: 24789521 DOI: 10.1007/s11120-014-0007-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Accepted: 04/14/2014] [Indexed: 06/03/2023]
Abstract
The mutant lacking enzymes BciA and BchU, that catalyzed reduction of the C8-vinyl group and methylation at the C20 position of bacteriochlorophyll (BChl) c, respectively, in the green sulfur bacterium Chlorobaculum tepidum, were constructed. This mutant accumulated C8-vinyl-BChl d derivatives, and a molecular structure of the major pigment was fully characterized by its NMR, mass, and circular dichroism spectra, as well as by chemical modification: (3(1) R)-8-vinyl-12-ethyl-(R[V,E])BChl d was confirmed as a new BChl d species in the cells. In vitro chlorosome-like self-aggregates of this pigment were prepared in an aqueous micellar solution, and formed more rapidly than those of (3(1) R)-8,12-diethyl-(R[E,E])BChl d isolated from the green sulfur bacterium Chlorobaculum parvum NCIB8327d synthesizing BChl d homologs. Their red-shifted Q y absorption bands were almost the same at 761 nm, and the value was larger than those of in vitro self-aggregates of R[E,E]BChl c (737 nm) and R[V,E]BChl c (726 nm), while the monomeric states of the former gave Q y bands at shorter wavelengths than those of the latter. Red shifts by self-aggregation of the two BChl d species were estimated to be 110 nm and much larger than those by BChls c (75 nm for [E,E] and 64 nm for [V,E]).
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Affiliation(s)
- Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, 830-0011, Japan,
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Orf GS, Blankenship RE. Chlorosome antenna complexes from green photosynthetic bacteria. PHOTOSYNTHESIS RESEARCH 2013; 116:315-31. [PMID: 23761131 DOI: 10.1007/s11120-013-9869-3] [Citation(s) in RCA: 176] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 06/06/2013] [Indexed: 05/18/2023]
Abstract
Chlorosomes are the distinguishing light-harvesting antenna complexes that are found in green photosynthetic bacteria. They contain bacteriochlorophyll (BChl) c, d, e in natural organisms, and recently through mutation, BChl f, as their principal light-harvesting pigments. In chlorosomes, these pigments self-assemble into large supramolecular structures that are enclosed inside a lipid monolayer to form an ellipsoid. The pigment assembly is dictated mostly by pigment-pigment interactions as opposed to protein-pigment interactions. On the bottom face of the chlorosome, the CsmA protein aggregates into a paracrystalline baseplate with BChl a, and serves as the interface to the next energy acceptor in the system. The exceptional light-harvesting ability at very low light conditions of chlorosomes has made them an attractive subject of study for both basic and applied science. This review, incorporating recent advancements, considers several important aspects of chlorosomes: pigment biosynthesis, organization of pigments and proteins, spectroscopic properties, and applications to bio-hybrid and bio-inspired devices.
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Affiliation(s)
- Gregory S Orf
- Departments of Chemistry and Biology, Washington University in St. Louis, Campus Box 1137, One Brookings Drive, St. Louis, MO, 63130, USA
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Harada J, Mizoguchi T, Satoh S, Tsukatani Y, Yokono M, Noguchi M, Tanaka A, Tamiaki H. Specific gene bciD for C7-methyl oxidation in bacteriochlorophyll e biosynthesis of brown-colored green sulfur bacteria. PLoS One 2013; 8:e60026. [PMID: 23560066 PMCID: PMC3613366 DOI: 10.1371/journal.pone.0060026] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2013] [Accepted: 02/20/2013] [Indexed: 11/18/2022] Open
Abstract
The gene named bciD, which encodes the enzyme involved in C7-formylation in bacteriochlorophyll e biosynthesis, was found and investigated by insertional inactivation in the brown-colored green sulfur bacterium Chlorobaculum limnaeum (previously called Chlorobium phaeobacteroides). The bciD mutant cells were green in color, and accumulated bacteriochlorophyll c homologs bearing the 7-methyl group, compared to C7-formylated BChl e homologs in the wild type. BChl-c homolog compositions in the mutant were further different from those in Chlorobaculum tepidum which originally produced BChl c: (3(1) S)-8-isobutyl-12-ethyl-BChl c was unusually predominant.
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Affiliation(s)
- Jiro Harada
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, Japan
- * E-mail: (JH); (HT)
| | - Tadashi Mizoguchi
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
| | - Souichirou Satoh
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Yusuke Tsukatani
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
| | - Makio Yokono
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Masato Noguchi
- Department of Medical Biochemistry, Kurume University School of Medicine, Kurume, Fukuoka, Japan
| | - Ayumi Tanaka
- Institute of Low Temperature Science, Hokkaido University, Sapporo, Hokkaido, Japan
- Core Research for Evolutional Science and Technology, Japan Science and Technology Agency, Sapporo, Hokkaido, Japan
| | - Hitoshi Tamiaki
- Graduate School of Life Sciences, Ritsumeikan University, Kusatsu, Shiga, Japan
- * E-mail: (JH); (HT)
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Comparative and Functional Genomics of Anoxygenic Green Bacteria from the Taxa Chlorobi, Chloroflexi, and Acidobacteria. FUNCTIONAL GENOMICS AND EVOLUTION OF PHOTOSYNTHETIC SYSTEMS 2012. [DOI: 10.1007/978-94-007-1533-2_3] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Multiple types of 8-vinyl reductases for (bacterio)chlorophyll biosynthesis occur in many green sulfur bacteria. J Bacteriol 2011; 193:4996-8. [PMID: 21764919 DOI: 10.1128/jb.05520-11] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two 8-vinyl reductases, BciA and BciB, have been identified in chlorophototrophs. The bciA gene of Chlorobaculum tepidum was replaced with genes similar to bciB from other green sulfur bacteria. Pigment analyses of the complemented strains showed that the bciB homologs encode 8-vinyl reductases similar to those of cyanobacteria.
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