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Fathir, Insan; Ashikaga, Mitsuhiro; Tanaka, Kiriha; Katano, Takashi; Nirasawa, Takashi; Kobayashi, Masayuki; Wang, Zheng-Yu; Nozawa, Tsunenori

doi:10.1023/a:1006146713751

Cited by 21 publications

(7 citation statements)

References 32 publications

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“…tepidum was 5410 Da. This is different from that calculated on the basis of its gene sequence [12], which predicts a value of 5529.4 Da and has a N‐terminal domain of Met‐Ala‐Glu‐Gln‐⋯. First‐cycle Edman degradation of the N‐terminal domain released two peaks, one with a very close elution time to that of phenylthiohydantoin‐Glu and another appeared as unknown substance.…”

Section: Resultscontrasting

confidence: 77%

N‐terminal methylation of the core light‐harvesting complex in purple photosynthetic bacteria

et al. 2002

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Several core light-harvesting complexes from both sulfur and non-sulfur purple photosynthetic bacteria have been identified to be methylated at the N-terminal K K-amino group of L L-polypeptides by using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and nuclear magnetic resonance. Monomethylation has been confirmed for the Nterminal alanine residues of the L L-polypeptides from Rhodospirillum rubrum, Thermochromatium tepidum and Chromatium vinosum, but not for the L L-polypeptide from Rhodobacter sphaeroides. The modification appears to be related with the amino acid sequence and charge distribution in the N-terminal end. Some common features and possible functions are discussed. ß

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Section: Resultscontrasting

confidence: 77%

N‐terminal methylation of the core light‐harvesting complex in purple photosynthetic bacteria

et al. 2002

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“…tepidum LH1 polypeptides revealed that three Asp in the ␣-polypeptide are located in the C-terminal region and are close to the BChl a-coordinating His residue (Fig. 8) (6,7). Three similar residues (two Glu and one Asp) are found in the C terminus of the LH1 ␣-polypeptide from the mesophilic purple bacterium Allochromatium (Ach.)…”

Section: Discussionmentioning

confidence: 97%

“…In a preliminary study, we found that the LH1 Q y absorption of Tch. tepidum core complex appeared to be affected by various cations used in the experiment (6). However, the LH1-RC samples used in the previous work were partially damaged, and the LH2 along with other two unknown proteins were not completely removed.…”

mentioning

confidence: 85%

Calcium Ions Are Involved in the Unusual Red Shift of the Light-harvesting 1 Qy Transition of the Core Complex in Thermophilic Purple Sulfur Bacterium Thermochromatium tepidum

Kimura

Hirano

et al. 2008

Journal of Biological Chemistry

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122

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Thermophilic purple sulfur bacterium, Thermochromatium tepidum, can grow at temperatures up to 58 degrees C and exhibits an unusual Qy absorption at 915 nm for the core light-harvesting complex (LH1), an approximately 35-nm red shift from those of its mesophilic counterparts. We demonstrate in this study, using a highly purified LH1-reaction center complex, that the LH1 Qy transition is strongly dependent on metal cations and Ca2+ is involved in the unusual red shift. Removal of the Ca2+ resulted in formation of a species with the LH1 Qy absorption at 880 nm, and addition of the Ca2+ to the 880-nm species recovered the native 915-nm form. Interchange between the two forms is fully reversible. Based on spectroscopic and isothermal titration calorimetry analyses, the Ca2+ binding to the LH1 complex was estimated to occur in a stoichiometric ratio of Ca2+/alphabeta-subunit = 1:1 and the binding constant was in 10(5) m(-1) order of magnitude, which is comparable with those for EF-hand Ca2+-binding proteins. Despite the high affinity, conformational changes in the LH1 complex upon Ca2+ binding were small and occurred slowly, with a typical time constant of approximately 6 min. Replacement of the Ca2+ with other metal cations caused blue shifts of the Qy bands depending on the property of the cations, indicating that the binding site is highly selective. Based on the amino acid sequences of the LH1 complex, possible Ca2+-binding sites are proposed that consist of several acidic amino acid residues near the membrane interfaces of the C-terminal region of the alpha-polypeptide and the N-terminal region of the beta-polypeptide.

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“…The respective samples will subsequently be labeled as Ca-LH1-RC and LH1-RC to keep common nomenclature. Most of the measurements were performed at 4.5 K to take advantage of the improved spectral resolution [4,5].…”

Section: Resultsmentioning

confidence: 99%

“…Thermochromatium (Tch.) tepidum, another recognized consumer of far-red light, exhibits the absorption peak at 914 nm [5].…”

Section: Introductionmentioning

confidence: 99%

Exciton Origin of Color-Tuning in Ca2+-Binding Photosynthetic Bacteria

Timpmann

Rätsep

Kangur

et al. 2021

IJMS

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Flexible color adaptation to available ecological niches is vital for the photosynthetic organisms to thrive. Hence, most purple bacteria living in the shade of green plants and algae apply bacteriochlorophyll a pigments to harvest near infra-red light around 850–875 nm. Exceptions are some Ca2+-containing species fit to utilize much redder quanta. The physical basis of such anomalous absorbance shift equivalent to ~5.5 kT at ambient temperature remains unsettled so far. Here, by applying several sophisticated spectroscopic techniques, we show that the Ca2+ ions bound to the structure of LH1 core light-harvesting pigment–protein complex significantly increase the couplings between the bacteriochlorophyll pigments. We thus establish the Ca-facilitated enhancement of exciton couplings as the main mechanism of the record spectral red-shift. The changes in specific interactions such as pigment–protein hydrogen bonding, although present, turned out to be secondary in this regard. Apart from solving the two-decade-old conundrum, these results complement the list of physical principles applicable for efficient spectral tuning of photo-sensitive molecular nano-systems, native or synthetic.

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Cited by 21 publications

References 32 publications

N‐terminal methylation of the core light‐harvesting complex in purple photosynthetic bacteria

N‐terminal methylation of the core light‐harvesting complex in purple photosynthetic bacteria

Calcium Ions Are Involved in the Unusual Red Shift of the Light-harvesting 1 Qy Transition of the Core Complex in Thermophilic Purple Sulfur Bacterium Thermochromatium tepidum

Exciton Origin of Color-Tuning in Ca2+-Binding Photosynthetic Bacteria

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