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Ion-pumping microbial rhodopsins.

Kandori H - Front Mol Biosci (2015)

Bottom Line: Ion-transporting proteins can be found in microbial rhodopsins, such as light-gated channels and light-driven pumps, which are the main tools in optogenetics.On the other hand, different kinds of H(+) and Cl(-) pumps have been found in marine bacteria, such as proteorhodopsin (PR) and Fulvimarina pelagi rhodopsin (FR), respectively.In addition, a light-driven Na(+) pump was found, Krokinobacter eikastus rhodopsin 2 (KR2).

View Article: PubMed Central - PubMed

Affiliation: Department of Frontier Materials and OptoBioTechnology Research Center, Nagoya Institute of Technology Nagoya, Japan.

ABSTRACT
Rhodopsins are light-sensing proteins used in optogenetics. The word "rhodopsin" originates from the Greek words "rhodo" and "opsis," indicating rose and sight, respectively. Although the classical meaning of rhodopsin is the red-colored pigment in our eyes, the modern meaning of rhodopsin encompasses photoactive proteins containing a retinal chromophore in animals and microbes. Animal and microbial rhodopsins possess 11-cis and all-trans retinal, respectively, to capture light in seven transmembrane α-helices, and photoisomerizations into all-trans and 13-cis forms, respectively, initiate each function. Ion-transporting proteins can be found in microbial rhodopsins, such as light-gated channels and light-driven pumps, which are the main tools in optogenetics. Light-driven pumps, such as archaeal H(+) pump bacteriorhodopsin (BR) and Cl(-) pump halorhodopsin (HR), were discovered in the 1970s, and their mechanism has been extensively studied. On the other hand, different kinds of H(+) and Cl(-) pumps have been found in marine bacteria, such as proteorhodopsin (PR) and Fulvimarina pelagi rhodopsin (FR), respectively. In addition, a light-driven Na(+) pump was found, Krokinobacter eikastus rhodopsin 2 (KR2). These light-driven ion-pumping microbial rhodopsins are classified as DTD, TSA, DTE, NTQ, and NDQ rhodopsins for BR, HR, PR, FR, and KR2, respectively. Recent understanding of ion-pumping microbial rhodopsins is reviewed in this paper.

No MeSH data available.


Chromophore molecules of microbial (left) and animal (right) rhodopsins. β-carotene (top) is the source of the chromophore, and all-trans and 11-cis retinal is bound to protein through the Schiff base linkage.
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Figure 2: Chromophore molecules of microbial (left) and animal (right) rhodopsins. β-carotene (top) is the source of the chromophore, and all-trans and 11-cis retinal is bound to protein through the Schiff base linkage.

Mentions: Microbial and animal rhodopsins share a common architecture of seven transmembrane α-helices with the N- and C-termini located extracellularly and intracellularly, respectively, but have almost no sequence homology and differ largely in their functions. Retinal, the aldehyde of vitamin A, is derived from β-carotene and is bound to the protein in the shape of all-trans and 11-cis forms in microbial and animal rhodopsins, respectively (Figure 2). Retinal is attached by a Schiff base linkage to the ε-amino group of a Lysine side chain in the middle of the 7th helix, and the retinal Schiff base is protonated in most cases (Figure 2).


Ion-pumping microbial rhodopsins.

Kandori H - Front Mol Biosci (2015)

Chromophore molecules of microbial (left) and animal (right) rhodopsins. β-carotene (top) is the source of the chromophore, and all-trans and 11-cis retinal is bound to protein through the Schiff base linkage.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585134&req=5

Figure 2: Chromophore molecules of microbial (left) and animal (right) rhodopsins. β-carotene (top) is the source of the chromophore, and all-trans and 11-cis retinal is bound to protein through the Schiff base linkage.
Mentions: Microbial and animal rhodopsins share a common architecture of seven transmembrane α-helices with the N- and C-termini located extracellularly and intracellularly, respectively, but have almost no sequence homology and differ largely in their functions. Retinal, the aldehyde of vitamin A, is derived from β-carotene and is bound to the protein in the shape of all-trans and 11-cis forms in microbial and animal rhodopsins, respectively (Figure 2). Retinal is attached by a Schiff base linkage to the ε-amino group of a Lysine side chain in the middle of the 7th helix, and the retinal Schiff base is protonated in most cases (Figure 2).

Bottom Line: Ion-transporting proteins can be found in microbial rhodopsins, such as light-gated channels and light-driven pumps, which are the main tools in optogenetics.On the other hand, different kinds of H(+) and Cl(-) pumps have been found in marine bacteria, such as proteorhodopsin (PR) and Fulvimarina pelagi rhodopsin (FR), respectively.In addition, a light-driven Na(+) pump was found, Krokinobacter eikastus rhodopsin 2 (KR2).

View Article: PubMed Central - PubMed

Affiliation: Department of Frontier Materials and OptoBioTechnology Research Center, Nagoya Institute of Technology Nagoya, Japan.

ABSTRACT
Rhodopsins are light-sensing proteins used in optogenetics. The word "rhodopsin" originates from the Greek words "rhodo" and "opsis," indicating rose and sight, respectively. Although the classical meaning of rhodopsin is the red-colored pigment in our eyes, the modern meaning of rhodopsin encompasses photoactive proteins containing a retinal chromophore in animals and microbes. Animal and microbial rhodopsins possess 11-cis and all-trans retinal, respectively, to capture light in seven transmembrane α-helices, and photoisomerizations into all-trans and 13-cis forms, respectively, initiate each function. Ion-transporting proteins can be found in microbial rhodopsins, such as light-gated channels and light-driven pumps, which are the main tools in optogenetics. Light-driven pumps, such as archaeal H(+) pump bacteriorhodopsin (BR) and Cl(-) pump halorhodopsin (HR), were discovered in the 1970s, and their mechanism has been extensively studied. On the other hand, different kinds of H(+) and Cl(-) pumps have been found in marine bacteria, such as proteorhodopsin (PR) and Fulvimarina pelagi rhodopsin (FR), respectively. In addition, a light-driven Na(+) pump was found, Krokinobacter eikastus rhodopsin 2 (KR2). These light-driven ion-pumping microbial rhodopsins are classified as DTD, TSA, DTE, NTQ, and NDQ rhodopsins for BR, HR, PR, FR, and KR2, respectively. Recent understanding of ion-pumping microbial rhodopsins is reviewed in this paper.

No MeSH data available.