Abstract
In microbial rhodopsins (also called retinal proteins), the retinal chromophore is used for harvesting light. A carotenoid molecule has been reported to complement the retinal as light harvesting antenna in bacterial retinal proteins, although examples are scarce. In this paper, we present the formation of a novel antenna complex between thermophilic rhodopsin (TR) and the carotenoid salinixanthin (Sal). The complex formation and its structure were studied using UV-visible absorption as well as circular dichroism (CD) spectroscopies. Our studies indicate that the complex is formed in both the trimeric and monomeric forms of TR. CD spectroscopy suggests that excitonic coupling takes place between retinal and Sal. The binding of Sal with artificial TR pigments derived from synthetic retinal analogues further supports the contribution of the retinal chromophore to the CD spectrum. These studies further support the possibility of interaction between the 4-keto ring of the Sal and the retinal in TR-Sal complexes. Temperature-dependent CD spectra indicate that the positive band (ca. 482 nm) of the bisignate CD spectra of the studied complexes originates from the contribution of excitonic coupling and induced chirality of Sal in the protein binding site. The presence of a relatively smaller glycine residue in the vicinity of the retinal chromophore in TR is proposed to be crucial for binding with Sal. The results are expected to shed light on the mechanism of retinal-carotenoid interactions in other biological systems.
| Original language | English |
|---|---|
| Pages (from-to) | 10-20 |
| Number of pages | 11 |
| Journal | Journal of Physical Chemistry B |
| Volume | 123 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - Oct 1 2019 |
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ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Surfaces, Coatings and Films
- Materials Chemistry
Cite this
Retinal-Salinixanthin Interactions in a Thermophilic Rhodopsin. / Misra, Ramprasad; Eliash, Tamar; Sudo, Yuki; Sheves, Mordechai.
In: Journal of Physical Chemistry B, Vol. 123, No. 1, 01.10.2019, p. 10-20.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Retinal-Salinixanthin Interactions in a Thermophilic Rhodopsin
AU - Misra, Ramprasad
AU - Eliash, Tamar
AU - Sudo, Yuki
AU - Sheves, Mordechai
PY - 2019/10/1
Y1 - 2019/10/1
N2 - In microbial rhodopsins (also called retinal proteins), the retinal chromophore is used for harvesting light. A carotenoid molecule has been reported to complement the retinal as light harvesting antenna in bacterial retinal proteins, although examples are scarce. In this paper, we present the formation of a novel antenna complex between thermophilic rhodopsin (TR) and the carotenoid salinixanthin (Sal). The complex formation and its structure were studied using UV-visible absorption as well as circular dichroism (CD) spectroscopies. Our studies indicate that the complex is formed in both the trimeric and monomeric forms of TR. CD spectroscopy suggests that excitonic coupling takes place between retinal and Sal. The binding of Sal with artificial TR pigments derived from synthetic retinal analogues further supports the contribution of the retinal chromophore to the CD spectrum. These studies further support the possibility of interaction between the 4-keto ring of the Sal and the retinal in TR-Sal complexes. Temperature-dependent CD spectra indicate that the positive band (ca. 482 nm) of the bisignate CD spectra of the studied complexes originates from the contribution of excitonic coupling and induced chirality of Sal in the protein binding site. The presence of a relatively smaller glycine residue in the vicinity of the retinal chromophore in TR is proposed to be crucial for binding with Sal. The results are expected to shed light on the mechanism of retinal-carotenoid interactions in other biological systems.
AB - In microbial rhodopsins (also called retinal proteins), the retinal chromophore is used for harvesting light. A carotenoid molecule has been reported to complement the retinal as light harvesting antenna in bacterial retinal proteins, although examples are scarce. In this paper, we present the formation of a novel antenna complex between thermophilic rhodopsin (TR) and the carotenoid salinixanthin (Sal). The complex formation and its structure were studied using UV-visible absorption as well as circular dichroism (CD) spectroscopies. Our studies indicate that the complex is formed in both the trimeric and monomeric forms of TR. CD spectroscopy suggests that excitonic coupling takes place between retinal and Sal. The binding of Sal with artificial TR pigments derived from synthetic retinal analogues further supports the contribution of the retinal chromophore to the CD spectrum. These studies further support the possibility of interaction between the 4-keto ring of the Sal and the retinal in TR-Sal complexes. Temperature-dependent CD spectra indicate that the positive band (ca. 482 nm) of the bisignate CD spectra of the studied complexes originates from the contribution of excitonic coupling and induced chirality of Sal in the protein binding site. The presence of a relatively smaller glycine residue in the vicinity of the retinal chromophore in TR is proposed to be crucial for binding with Sal. The results are expected to shed light on the mechanism of retinal-carotenoid interactions in other biological systems.
UR - http://www.scopus.com/inward/record.url?scp=85059888149&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85059888149&partnerID=8YFLogxK
U2 - 10.1021/acs.jpcb.8b06795
DO - 10.1021/acs.jpcb.8b06795
M3 - Article
C2 - 30525616
AN - SCOPUS:85059888149
VL - 123
SP - 10
EP - 20
JO - Journal of Physical Chemistry B Materials
JF - Journal of Physical Chemistry B Materials
SN - 1520-6106
IS - 1
ER -