Limits...
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.


Double difference spectra between the LOV2-Jα and LOV2 core in the 1750–1600 cm−1 region. Spectra of phot1 (black lines), phot2 (red lines), and neo1 (blue lines) are shown at 150, 250, 260, 273, and 295 K. This figure is modified from Ref 53.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC5036776&req=5

f6-7_89: Double difference spectra between the LOV2-Jα and LOV2 core in the 1750–1600 cm−1 region. Spectra of phot1 (black lines), phot2 (red lines), and neo1 (blue lines) are shown at 150, 250, 260, 273, and 295 K. This figure is modified from Ref 53.

Mentions: Influence of the Jα helix can be seen for the negative band at 1694 cm−1 for both phot1 (Fig. 5a) and phot2 (Fig. 5b). In both cases, the negative 1694 cm−1 band intensified in the presence of the Jα helix. This is also the case at 150 and 250 K, which can be seen more clearly in the double difference spectra (see below; Fig. 6). Since the C2=O and C4=O stretching vibrations of FMN are located at 1676–1678 and 1712–1713 cm−1, respectively, the negative band probably originates from an amide-I vibration that corresponds to the loop structure. The corresponding positive band is presumably located at 1686–1687 cm−1, where a lower frequency indicates the strengthened hydrogen bond of the loop structure.


Light-induced structural changes of the LOV2 domains in various phototropins revealed by FTIR spectroscopy
Double difference spectra between the LOV2-Jα and LOV2 core in the 1750–1600 cm−1 region. Spectra of phot1 (black lines), phot2 (red lines), and neo1 (blue lines) are shown at 150, 250, 260, 273, and 295 K. This figure is modified from Ref 53.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC5036776&req=5

f6-7_89: Double difference spectra between the LOV2-Jα and LOV2 core in the 1750–1600 cm−1 region. Spectra of phot1 (black lines), phot2 (red lines), and neo1 (blue lines) are shown at 150, 250, 260, 273, and 295 K. This figure is modified from Ref 53.
Mentions: Influence of the Jα helix can be seen for the negative band at 1694 cm−1 for both phot1 (Fig. 5a) and phot2 (Fig. 5b). In both cases, the negative 1694 cm−1 band intensified in the presence of the Jα helix. This is also the case at 150 and 250 K, which can be seen more clearly in the double difference spectra (see below; Fig. 6). Since the C2=O and C4=O stretching vibrations of FMN are located at 1676–1678 and 1712–1713 cm−1, respectively, the negative band probably originates from an amide-I vibration that corresponds to the loop structure. The corresponding positive band is presumably located at 1686–1687 cm−1, where a lower frequency indicates the strengthened hydrogen bond of the loop structure.

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.