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Light-induced structural changes of the LOV2 domains in various phototropins revealed by FTIR spectroscopy

View Article: PubMed Central - PubMed

ABSTRACT

Phototropin (Phot), a blue-light photoreceptor in plants, consists of two FMN-binding domains (named LOV1 and LOV2) and a serine/threonine (Ser/Thr) kinase domain. We have investigated light-induced structural changes of LOV domains, which lead to the activation of the kinase domain, by means of light-induced difference FTIR spectroscopy. FTIR spectroscopy revealed that the reactive cysteine is protonated in both unphotolyzed and triplet-excited states, which is difficult to detect by other methods such as X-ray crystallography. In this review, we describe the light-induced structural changes of hydrogen-bonding environment of FMN chromophore and protein backbone in Adiantum neo1-LOV2 in the C=O stretching region by use of 13C-labeled samples. We also describe the comprehensive FTIR analysis of LOV2 domains among Arabidopsis phot1, phot2, and Adiantum neo1 with and without Jα helix domain.

No MeSH data available.


(a) Protein structure of oat phot1-LOV2 (pdb entry 2V1A)26. The whole structure is shown as a ribbon drawing. The helices, turns, and sheets in the LOV-core domain are colored red, green, and yellow, respectively. Jα helix is colored magenta. The FMN and reactive cysteine (Cys450 in the oat phto1-LOV2) are shown as a ball-and-stick drawing. The folding motif of this protein is characteristic of the PAS superfamily. Figure was drawn with PyMOL software59. (b) Photoreaction scheme for the LOV domains.
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f1-7_89: (a) Protein structure of oat phot1-LOV2 (pdb entry 2V1A)26. The whole structure is shown as a ribbon drawing. The helices, turns, and sheets in the LOV-core domain are colored red, green, and yellow, respectively. Jα helix is colored magenta. The FMN and reactive cysteine (Cys450 in the oat phto1-LOV2) are shown as a ball-and-stick drawing. The folding motif of this protein is characteristic of the PAS superfamily. Figure was drawn with PyMOL software59. (b) Photoreaction scheme for the LOV domains.

Mentions: Phototropin consists of about 1000 amino acid residues and two prosthetic FMN molecules. The FMN-binding domains are located at the N-terminal half, and the C-terminal half has a serine/threonine (Ser/Thr) kinase domain. The photochemical reaction of FMN yields kinase activation through a change in the domain-domain interaction, although the mechanism is not yet clear. The two FMN-binding domains (ca. 100 residues) are named LOV1 and LOV2, since they have primary21 and tertiary22 structures highly homologous to bacterial light-sensor PYP (photoactive yellow protein), oxygen-sensor FixL, and voltage-sensor HERG of a channel protein so that the domain is called the LOV (light, oxygen, and voltage sensing) domain (Fig. 1a). The protein fold belongs to the PAS (Per-Arnt-Sim) superfamily. X-ray crystallography showed that the structures of various LOV domains, LOV1 domains from Chlamydomonas phot23 and Arabidopsis phot1 and phot224 and LOV2 domains from Adiantum neo122,25 and oat phot126, all reported similar protein architectures.


Light-induced structural changes of the LOV2 domains in various phototropins revealed by FTIR spectroscopy
(a) Protein structure of oat phot1-LOV2 (pdb entry 2V1A)26. The whole structure is shown as a ribbon drawing. The helices, turns, and sheets in the LOV-core domain are colored red, green, and yellow, respectively. Jα helix is colored magenta. The FMN and reactive cysteine (Cys450 in the oat phto1-LOV2) are shown as a ball-and-stick drawing. The folding motif of this protein is characteristic of the PAS superfamily. Figure was drawn with PyMOL software59. (b) Photoreaction scheme for the LOV domains.
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5036776&req=5

f1-7_89: (a) Protein structure of oat phot1-LOV2 (pdb entry 2V1A)26. The whole structure is shown as a ribbon drawing. The helices, turns, and sheets in the LOV-core domain are colored red, green, and yellow, respectively. Jα helix is colored magenta. The FMN and reactive cysteine (Cys450 in the oat phto1-LOV2) are shown as a ball-and-stick drawing. The folding motif of this protein is characteristic of the PAS superfamily. Figure was drawn with PyMOL software59. (b) Photoreaction scheme for the LOV domains.
Mentions: Phototropin consists of about 1000 amino acid residues and two prosthetic FMN molecules. The FMN-binding domains are located at the N-terminal half, and the C-terminal half has a serine/threonine (Ser/Thr) kinase domain. The photochemical reaction of FMN yields kinase activation through a change in the domain-domain interaction, although the mechanism is not yet clear. The two FMN-binding domains (ca. 100 residues) are named LOV1 and LOV2, since they have primary21 and tertiary22 structures highly homologous to bacterial light-sensor PYP (photoactive yellow protein), oxygen-sensor FixL, and voltage-sensor HERG of a channel protein so that the domain is called the LOV (light, oxygen, and voltage sensing) domain (Fig. 1a). The protein fold belongs to the PAS (Per-Arnt-Sim) superfamily. X-ray crystallography showed that the structures of various LOV domains, LOV1 domains from Chlamydomonas phot23 and Arabidopsis phot1 and phot224 and LOV2 domains from Adiantum neo122,25 and oat phot126, all reported similar protein architectures.

View Article: PubMed Central - PubMed

ABSTRACT

Phototropin (Phot), a blue-light photoreceptor in plants, consists of two FMN-binding domains (named LOV1 and LOV2) and a serine/threonine (Ser/Thr) kinase domain. We have investigated light-induced structural changes of LOV domains, which lead to the activation of the kinase domain, by means of light-induced difference FTIR spectroscopy. FTIR spectroscopy revealed that the reactive cysteine is protonated in both unphotolyzed and triplet-excited states, which is difficult to detect by other methods such as X-ray crystallography. In this review, we describe the light-induced structural changes of hydrogen-bonding environment of FMN chromophore and protein backbone in Adiantum neo1-LOV2 in the C=O stretching region by use of 13C-labeled samples. We also describe the comprehensive FTIR analysis of LOV2 domains among Arabidopsis phot1, phot2, and Adiantum neo1 with and without Jα helix domain.

No MeSH data available.