Atomic force microscopic analysis of the light-harvesting complex 2 from purple photosynthetic bacterium Thermochromatium tepidum

Morimoto, Masayuki; Hirao, Haruna; Kondo, Masaharu; Dewa, Takehisa; Kimura, Yukihiro; Wang-Otomo, Zheng-Yu; Asakawa, Hitoshi; Saga, Yoshitaka

doi:10.1007/s11120-023-01010-4

Cited by 3 publications

(1 citation statement)

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“…Atomic force microscopy has revealed that the Tch. tepidum LH2 complex forms a circular arrangement of 8 subunits (Morimoto et al, 2023), but thus far, no evidence exists for a Ca 2+ ‐reinforced network in the Tch. tepidum LH2 like that found in its LH1 complex.…”

Section: Chimeric Thermochromatium Tepidum Photocomplexes and Lh2mentioning

confidence: 99%

Calcium and the ecology of photosynthesis in purple sulfur bacteria

Madigan,

Sattley,

Kimura

et al. 2024

Environmental Microbiology

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The ecological success of purple sulfur bacteria (PSB) is linked to their ability to collect near‐infrared solar energy by membrane‐integrated, pigment–protein photocomplexes. These include a Core complex containing both light‐harvesting 1 (LH1) and reaction centre (RC) components (called the LH1–RC photocomplex) present in all PSB and a peripheral light‐harvesting complex present in most but not all PSB. In research to explain the unusual absorption properties of the thermophilic purple sulfur bacterium Thermochromatium tepidum, Ca2+ was discovered bound to LH1 polypeptides in its LH1–RC; further work showed that calcium controls both the thermostability and unusual spectrum of the Core complex. Since then, Ca2+ has been found in the LH1–RC photocomplexes of several other PSB, including mesophilic species, but not in the LH1–RC of purple non‐sulfur bacteria. Here we focus on four species of PSB—two thermophilic and two mesophilic—and describe how Ca2+ is integrated into and affects their photosynthetic machinery and why this previously overlooked divalent metal is a key nutrient for their ecological success.

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Section: Chimeric Thermochromatium Tepidum Photocomplexes and Lh2mentioning

confidence: 99%

Calcium and the ecology of photosynthesis in purple sulfur bacteria

Madigan,

Sattley,

Kimura

et al. 2024

Environmental Microbiology

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Supramolecular chirality in self-assembly of zinc protobacteriochlorophyll-d analogs possessing enantiomeric esterifying groups

Yasui,

Tamiaki

2024

Photochem Photobiol Sci

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Zinc 3-hydroxymethyl-pyroprotopheophorbides-a esterified with a chiral secondary alcohol at the 17-propionate residue were prepared as bacteriochlorophyll-d analogs. The synthetic zinc 31-hydroxy-131-oxo-porphyrins self-aggregated in an aqueous Triton X-100 micellar solution to give red-shifted and broadened Soret and Qy absorption bands in comparison with their monomeric bands. The intense, exciton-coupled circular dichroism spectra of their self-aggregates were dependent on the chirality of the esterifying groups. The observation indicated that the self-aggregates based on the J-type stacking of the porphyrin cores were sensitive to the peripheral 17-propionate residues. The supramolecular structures of the present J-aggregates as models of bacteriochlorophyll aggregates in natural chlorosomes were remotely regulated by the esterifying groups. Graphical abstract

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