scholarly journals Structural and Spectroscopic Properties of a Reaction Center Complex from the Chlorosome-Lacking Filamentous Anoxygenic Phototrophic Bacterium Roseiflexus castenholzii

2005 ◽  
Vol 187 (5) ◽  
pp. 1702-1709 ◽  
Author(s):  
Mitsunori Yamada ◽  
Hui Zhang ◽  
Satoshi Hanada ◽  
Kenji V. P. Nagashima ◽  
Keizo Shimada ◽  
...  
Keyword(s):  
Reaction Center ◽  
Phylogenetic Trees ◽  
Light Harvesting ◽  
Purple Bacteria ◽  
Photosynthetic Apparatus ◽  
Spectroscopic Properties ◽  
Phototrophic Bacteria ◽  
Amino Acid Sequences ◽  
Anoxygenic Phototrophic Bacteria ◽  
Reading Frame

ABSTRACT The photochemical reaction center (RC) complex of Roseiflexus castenholzii, which belongs to the filamentous anoxygenic phototrophic bacteria (green filamentous bacteria) but lacks chlorosomes, was isolated and characterized. The genes coding for the subunits of the RC and the light-harvesting proteins were also cloned and sequenced. The RC complex was composed of L, M, and cytochrome subunits. The cytochrome subunit showed a molecular mass of approximately 35 kDa, contained hemes c, and functioned as the electron donor to the photo-oxidized special pair of bacteriochlorophylls in the RC. The RC complex appeared to contain three molecules of bacteriochlorophyll and three molecules of bacteriopheophytin, as in the RC preparation from Chloroflexus aurantiacus. Phylogenetic trees based on the deduced amino acid sequences of the RC subunits suggested that R. castenholzii had diverged from C. aurantiacus very early after the divergence of filamentous anoxygenic phototrophic bacteria from purple bacteria. Although R. castenholzii is phylogenetically related to C. aurantiacus, the arrangement of its puf genes, which code for the light-harvesting proteins and the RC subunits, was different from that in C. aurantiacus and similar to that in purple bacteria. The genes are found in the order pufB, -A, -L, -M, and -C, with the pufL and pufM genes forming one continuous open reading frame. Since the photosynthetic apparatus and genes of R. castenholzii have intermediate characteristics between those of purple bacteria and C. aurantiacus, it is likely that they retain many features of the common ancestor of purple bacteria and filamentous anoxygenic phototrophic bacteria.

scholarly journals Phylogeny of Anoxygenic Photosynthesis Based on Sequences of Photosynthetic Reaction Center Proteins and a Key Enzyme in Bacteriochlorophyll Biosynthesis, the Chlorophyllide Reductase

2019 ◽  
Vol 7 (11) ◽  
pp. 576 ◽  
Author(s):  
Johannes F. Imhoff ◽  
Tanja Rahn ◽  
Sven Künzel ◽  
Sven C. Neulinger
Keyword(s):  
16S Rrna ◽  
Reaction Center ◽  
Purple Bacteria ◽  
Photosynthetic Reaction Center ◽  
Phototrophic Bacteria ◽  
Anoxygenic Phototrophic Bacteria ◽  
Type Ii ◽  
Phylogenetic Relations ◽  
Key Enzyme ◽  
Bacteriochlorophyll Biosynthesis

Photosynthesis is a key process for the establishment and maintenance of life on earth, and it is manifested in several major lineages of the prokaryote tree of life. The evolution of photosynthesis in anoxygenic photosynthetic bacteria is of major interest as these have the most ancient roots of photosynthetic systems. The phylogenetic relations between anoxygenic phototrophic bacteria were compared on the basis of sequences of key proteins of the type-II photosynthetic reaction center, including PufLM and PufH (PuhA), and a key enzyme of bacteriochlorophyll biosynthesis, the light-independent chlorophyllide reductase BchXYZ. The latter was common to all anoxygenic phototrophic bacteria, including those with a type-I and those with a type-II photosynthetic reaction center. The phylogenetic considerations included cultured phototrophic bacteria from several phyla, including Proteobacteria (138 species), Chloroflexi (five species), Chlorobi (six species), as well as Heliobacterium modesticaldum (Firmicutes), Chloracidobacterium acidophilum (Acidobacteria), and Gemmatimonas phototrophica (Gemmatimonadetes). Whenever available, type strains were studied. Phylogenetic relationships based on a photosynthesis tree (PS tree, including sequences of PufHLM-BchXYZ) were compared with those of 16S rRNA gene sequences (RNS tree). Despite some significant differences, large parts were congruent between the 16S rRNA phylogeny and photosynthesis proteins. The phylogenetic relations demonstrated that bacteriochlorophyll biosynthesis had evolved in ancestors of phototrophic green bacteria much earlier as compared to phototrophic purple bacteria and that multiple events independently formed different lineages of aerobic phototrophic purple bacteria, many of which have very ancient roots. The Rhodobacterales clearly represented the youngest group, which was separated from other Proteobacteria by a large evolutionary gap.

Recovery of the photosynthetic apparatus from photoinhibition during dark incubation of the green alga Dunaliella salina

1999 ◽  
Vol 26 (7) ◽  
pp. 679 ◽  
Author(s):  
Jürgen E. W. Polle ◽  
Anastasios Melis
Keyword(s):  
Reaction Center ◽  
Dunaliella Salina ◽  
De Novo ◽  
Light Harvesting ◽  
Photosynthetic Apparatus ◽  
D1 Protein ◽  
Dark Incubation ◽  
Chl A ◽  
Lag Period ◽  
Stressed Cells

The light-independent recovery of the photosynthetic apparatus from photoinhibition was monitored upon a transition of irradiance-stressed Dunaliella salina Teod. to darkness. Upon dark incubation, the chlorophyll (Chl) a /Chl b ratio of the cells decreased promptly with a half-time of 2.5 h from about 12:1 to about 5:1. In contrast, dark incubation of control cells resulted in only a negligible change of the Chl a /Chl b ratio. During dark incubation of irradiance-stressed cells, the level of the Chl a and b light-harvesting proteins of photosystem II (PSII) increased, a change accompanied by alterations in the composition of these light-harvesting proteins. The amount of photodamaged PSII, measured from the relative amount of a 160 kDa protein complex which contains the photodamaged D1 reaction center protein, decreased during dark incubation after an initial lag period. Concomitantly, the amount of functional PSII, measured from the 32 kDa form of D1, increased slightly in the dark. The results show that, in the dark, photodamaged D1 is slowly removed upon degradation from the thylakoid membrane and replaced by a de novo synthesized D1 protein. The amount of reaction center proteins and number of photochemically active PSI centers increased in the dark. These results suggest that thylakoid membranes of irradiance-stressed D. salina exist in a state of dynamic flux. We conclude that several aspects of the D. salina recovery from photoinhibition are light independent.

A Dual Role for Ca2+ in Expanding the Spectral Diversity and Stability of Light-Harvesting 1 Reaction Center Photocomplexes of Purple Phototrophic Bacteria

Biochemistry ◽  
2019 ◽  
Vol 58 (25) ◽  
pp. 2844-2852 ◽  
Author(s):  
Michie Imanishi ◽  
Mizuki Takenouchi ◽  
Shinichi Takaichi ◽  
Shiori Nakagawa ◽  
Yoshitaka Saga ◽  
...  
Keyword(s):  
Reaction Center ◽  
Light Harvesting ◽  
Dual Role ◽  
Phototrophic Bacteria

scholarly journals The orf162b Sequence ofRhodobacter capsulatus Encodes a Protein Required for Optimal Levels of Photosynthetic Pigment-Protein Complexes

2000 ◽  
Vol 182 (19) ◽  
pp. 5440-5447 ◽  
Author(s):  
Muktak Aklujkar ◽  
Andrea L. Harmer ◽  
Roger C. Prince ◽  
J. Thomas Beatty
Keyword(s):  
Rhodobacter Capsulatus ◽  
Light Harvesting ◽  
Protein Complexes ◽  
Photosynthetic Pigment ◽  
Photosynthetic Apparatus ◽  
Coding Region ◽  
Reading Frame ◽  
Light Harvesting Complex ◽  
Pseudostationary Phase ◽  
Light Harvesting Complex Ii

ABSTRACT The orf162b sequence, the second open reading frame 3′ of the reaction center (RC) H protein gene puhA in theRhodobacter capsulatus photosynthesis gene cluster, is shown to be transcribed from a promoter located 5′ of puhA. A nonpolar mutation of orf162b was generated by replacing most of the coding region with an antibiotic resistance cartridge. Although the mutant strain initiated rapid photosynthetic growth, growth slowed progressively and cultures often entered a pseudostationary phase. The amounts of the RC and light harvesting complex I (LHI) in cells obtained from such photosynthetic cultures were abnormally low, but these deficiencies were less severe when the mutant was grown to a pseudostationary phase induced by low aeration in the absence of illumination. The orf162b mutation did not significantly affect the expression of apufB::lacZ translationally in-frame gene fusion under the control of the puf promoter, indicating normal transcription and translation of RC and LHI genes. Spontaneous secondary mutations in the strain with theorf162b disruption resulted in a bypass of the photosynthetic growth retardation and reduced the level of light harvesting complex II. These results and the presence of sequences similar to orf162b in other species indicate that the Orf162b protein is required for normal levels of the photosynthetic apparatus in purple photosynthetic bacteria.

scholarly journals The PuhB Protein of Rhodobacter capsulatus Functions in Photosynthetic Reaction Center Assembly with a Secondary Effect on Light-Harvesting Complex 1

2005 ◽  
Vol 187 (4) ◽  
pp. 1334-1343 ◽  
Author(s):  
Muktak Aklujkar ◽  
Roger C. Prince ◽  
J. Thomas Beatty
Keyword(s):  
Reaction Center ◽  
Rhodobacter Capsulatus ◽  
Light Harvesting ◽  
Expression System ◽  
Photosynthetic Apparatus ◽  
Photosynthetic Reaction Center ◽  
Growth Conditions ◽  
Physiological Adaptation ◽  
Light Harvesting Complex ◽  
The Core

ABSTRACT The core of the photosynthetic apparatus of purple photosynthetic bacteria such as Rhodobacter capsulatus consists of a reaction center (RC) intimately associated with light-harvesting complex 1 (LH1) and the PufX polypeptide. The abundance of the RC and LH1 components was previously shown to depend on the product of the puhB gene (formerly known as orf214). We report here that disruption of puhB diminishes RC assembly, with an indirect effect on LH1 assembly, and reduces the amount of PufX. Under semiaerobic growth conditions, the core complex was present at a reduced level in puhB mutants. After transfer of semiaerobically grown cultures to photosynthetic (anaerobic illuminated) conditions, the RC/LH1 complex became only slightly more abundant, and the amount of PufX increased as cells began photosynthetic growth. We discovered that the photosynthetic growth of puhB disruption strains of R. capsulatus starts after a long lag period, which is due to physiological adaptation rather than secondary mutations. Using a hybrid protein expression system, we determined that the three predicted transmembrane segments of PuhB are capable of spanning a cell membrane and that the second transmembrane segment could mediate self-association of PuhB. We discuss the possible function of PuhB as a dimeric RC assembly factor.

scholarly journals Anoxygenic phototroph pufLM gene sequences derived from tropical aquatic sampling sites: Diversity, distribution, and phylogenetics

2020 ◽  
Vol 2 (7A) ◽  
Author(s):  
Elizabeth Padilla Crespo ◽  
Lois Gordils ◽  
Xelimar Ramirez ◽  
Ruben Michael Ceballos
Keyword(s):  
Purple Bacteria ◽  
Phototrophic Bacteria ◽  
Anoxygenic Phototrophic Bacteria ◽  
Purple Sulfur Bacteria ◽  
Gene Sequences ◽  
Water Lily ◽  
Tropical Environments ◽  
Sulfur Bacteria ◽  
Rich Diversity ◽  
Freshwater Pond

Purple sulfur bacteria (PSB) and purple non-sulfur bacteria (PNSB) are characterized by their ability to perform anoxygenic photosynthesis. PSB and PNSB are ubiquitously found in coastal waters, enclosed lagoons, stagnant water, mangrove soils, estuaries, and similar environments. In this study, we examine microbial diversity in PSB enrichments derived from a variety of tropical sampling sites (e.g., Thailand, Puerto Rico) associated with shrimp ponds, coastal mangroves, fresh water ponds, and Nymphaeaceae (i.e., water lily) plant tissue. Since 16S rRNA-based analyses are inadequate to describe the diversity of phototrophic bacteria, other biomarkers (e.g., pufLM) are used to construct phylogenies and elucidate biogeography. Our samples indicate that the majority of sequences associated with freshwater pond PSB were related to known marine, halophilic, or salt-tolerant PSB (e.g., Marichromatium, Allochromatium, Thiococcus, and Thiohalocapsa). Phylotypes not closely-associated with known species of PSB (or PNSB) were also found. PNSB gene sequences, which appear to be related to Rhodopseudomonas and Rhodoplanes, were mostly found in freshwater samples and from Nymphaeaceae plant tissues, suggesting a difference in the ecology and distribution of these two broader bacterial groups. This difference is likely due to differences in habitat such as physical (e.g., temperature) and chemical parameters (e.g., salinity). Our preliminary analyses demonstrate a rich diversity of anoxygenic phototrophic bacteria from tropical sampling sites. Few studies have described the diversity of purple bacteria in tropical environments using full pufLM gene sequences. Employing next-generation sequencing (NGS) appears to provide greater resolution towards a deeper understanding of the global diversity and distribution of these anoxygenic phototrophs.

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