Orientation of reaction center complexes fromRhodobacter sphaeroides in proteoliposomes and the effect ofo-phenanthroline on electrogenesis during primary photochemical reaction

1989 ◽  
Vol 21 (4) ◽  
pp. 519-526 ◽  
Author(s):  
Andrey A. Kondrashin ◽  
Aleksey Yu. Semenov ◽  
Mahir D. Mamedov ◽  
Lel A. Drachev ◽  
Natalia I. Zakharova
Keyword(s):  
Reaction Center ◽  
Photochemical Reaction ◽  
Reaction Center Complexes ◽  
Primary Photochemical Reaction

Paraquat (Methylviologen): Its Interference with Primary Photochemical Reactions

1993 ◽  
Vol 48 (3-4) ◽  
pp. 374-378 ◽  
Author(s):  
Tetsuo Hiyama ◽  
Akira Ohinata ◽  
Shin-ichi Kobayashi
Keyword(s):  
Reaction Center ◽  
Electron Donor ◽  
Photosystem I ◽  
Photochemical Reaction ◽  
Photochemical Reactions ◽  
The Other ◽  
Primary Photochemical Reaction

Paraquat(methylviologen), a widely used nonspecific herbicide, is ptoreduced in the primary photochemical reaction of photosystemI. Using two types of the photosystem I reaction center preparations, i.e. one with FeSA/FeSB and the other without, the immediate electron donor to methylviologen was determined to be FeSx (P430) rather than FeSA/FeSB.

Wavelength controlled production of SO4- radicals in the ultraviolet photolysis of ceric sulfate solutions

1984 ◽  
Vol 37 (3) ◽  
pp. 475 ◽  
Author(s):  
RW Matthews
Keyword(s):  
Rate Constants ◽  
Photochemical Reaction ◽  
Transfer Reaction ◽  
Quantum Yields ◽  
Oh Radical ◽  
Transfer Energy ◽  
Fluorescence Measurements ◽  
Sulfate Solutions ◽  
Ultraviolet Photolysis ◽  
Primary Photochemical Reaction

Solutions of cerium(III)/(IV) and formic acid in 0.4 M sulfuric acid have been photolysed under 254 nm and 365 nm light. Marked differences in the reaction kinetics and quantum yields are observed at the two different wavelengths. At 365 nm, the reactions leading to cerium(IV) reduction are caused almost exclusively by the SO4- radical. The ratio of rate constants, k(SO4- + CeIII)/ k(SO4- + HCOOH), is 116 � 11 and the quantum yield of sulfate radicals, ф(SO4-), is 0.023 � 0.002. At 254 nm, the reactions leading to cerium(IV) reduction are caused mainly by the OH radical, but approximately 35% of the oxidizing radicals formed in the primary photochemical reaction are SO4-. Cerium(III) species, excited at 254 nm, transfer energy to cerium(IV) and this results in an additional yield of OH and SO4- radicals. Fluorescence measurements confirmed the efficiency of the energy transfer reaction. The ratio of rate constants, k(OH+CeIII)/k(OH+HCOOH), is 2.22 � 0.18 and ф(CeIV*) and ф(CelIII*) giving oxidizing radicals are 0.116 � 0.010 and 0.0083 � 0.0008 respectively. Thus about 5 times more total oxidizing radicals are produced from excited cerium(IV) species at 254 nm than at 365 nm.

scholarly journals Using the Endogenous CRISPR-Cas System of Heliobacterium modesticaldum To Delete the Photochemical Reaction Center Core Subunit Gene

2019 ◽  
Vol 85 (23) ◽  
Author(s):  
Patricia L. Baker ◽  
Gregory S. Orf ◽  
Kimberly Kevershan ◽  
Michael E. Pyne ◽  
Taner Bicer ◽  
...  
Keyword(s):  
Homologous Recombination ◽  
Genome Editing ◽  
Reaction Center ◽  
Photochemical Reaction ◽  
Genetic Locus ◽  
Gene Replacement ◽  
Type I ◽  
Content Type ◽  
Heliobacterium Modesticaldum

ABSTRACT In Heliobacterium modesticaldum, as in many Firmicutes, deleting genes by homologous recombination using standard techniques has been extremely difficult. The cells tend to integrate the introduced plasmid into the chromosome by a single recombination event rather than perform the double recombination required to replace the targeted locus. Transformation with a vector containing only a homologous recombination template for replacement of the photochemical reaction center gene pshA produced colonies with multiple genotypes, rather than a clean gene replacement. To address this issue, we required an additional means of selection to force a clean gene replacement. In this study, we report the genetic structure of the type I-A and I-E CRISPR-Cas systems from H. modesticaldum, as well as methods to leverage the type I-A system for genome editing. In silico analysis of the CRISPR spacers revealed a potential consensus protospacer adjacent motif (PAM) required for Cas3 recognition, which was then tested using an in vivo interference assay. Introduction of a homologous recombination plasmid that carried a miniature CRISPR array targeting sequences in pshA (downstream of a naturally occurring PAM sequence) produced nonphototrophic transformants with clean replacements of the pshA gene with ∼80% efficiency. Mutants were confirmed by PCR, sequencing, optical spectroscopy, and growth characteristics. This methodology should be applicable to any genetic locus in the H. modesticaldum genome. IMPORTANCE The heliobacteria are the only phototrophic members of the largely Gram-positive phylum Firmicutes, which contains medically and industrially important members, such as Clostridium difficile and Clostridium acetobutylicum. Heliobacteria are of interest in the study of photosynthesis because their photosynthetic system is unique and the simplest known. Since their discovery in the early 1980s, work on the heliobacteria has been hindered by the lack of a genetic transformation system. The problem of introducing foreign DNA into these bacteria has been recently rectified by our group; however, issues still remained for efficient genome editing. The significance of this work is that we have characterized the endogenous type I CRISPR-Cas system in the heliobacteria and leveraged it to assist in genome editing. Using the CRISPR-Cas system allowed us to isolate transformants with precise replacement of the pshA gene encoding the main subunit of the photochemical reaction center.

Ultrafast Photodynamics and Quantitative Evaluation of Biohybrid Photosynthetic Antenna and Reaction Center Complexes Generating Photocurrent

2020 ◽  
Vol 124 (16) ◽  
pp. 8605-8615 ◽  
Author(s):  
Yusuke Yoneda ◽  
Akari Goto ◽  
Nobutaka Takeda ◽  
Hiromi Harada ◽  
Masaharu Kondo ◽  
...  
Keyword(s):  
Reaction Center ◽  
Quantitative Evaluation ◽  
Reaction Center Complexes ◽  
Photosynthetic Antenna
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