Different Role of the Jα Helix in the Light-Induced Activation of the LOV2 Domains in Various Phototropins

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• 作者：Takayuki Koyama ; Tatsuya Iwata ; Atsushi Yamamoto ; Yoshiaki Sato ; Daisuke Matsuoka ; Satoru Tokutomi ; Hideki Kandori
• 刊名：Biochemistry
• 出版年：2009
• 出版时间：August 18, 2009
• 年：2009
• 卷：48
• 期：32
• 页码：7621-7628
• 全文大小：914K
• 年卷期：v.48,no.32(August 18, 2009)
• ISSN：1520-4995

文摘

Phototropins (phot) are blue light receptors in plants which are involved in phototropism, stomatal opening, and chloroplast movements. Phototropin has two LOV domains (LOV1 and LOV2), and the LOV2 domain is responsible for activation of Ser/Thr kinase. There is an α-helix at the C-terminal side of the LOV2 domain, which is called the Jα helix. The functional importance of the Jα helix has been established for Arabidopsis phot1, where light-induced structural perturbation takes place in the Jα helix during the photocycle of LOV2 domains. However, the present FTIR study reports a different role of the Jα helix in light-induced signal transduction of LOV2 domains. Here we construct LOV2 domains with (LOV-Jα) and without (LOV-core) the Jα helix for Arabidopsis phot1 and phot2 and Adiantum neochrome 1 and compare their light-induced difference FTIR spectra. Light-induced protein structural changes differ significantly between LOV-Jα and LOV-core for Arabidopsis phot1 [Yamamoto, A., Iwata, T., Sato, Y., Matsuoka, D., Tokutomi, S., and Kandori, H. (2009) Biophys. J. 96, 2771−2778]. In contrast, the difference spectra are identical between LOV-Jα and LOV-core for Adiantum neochrome 1. In Arabidopsis phot2, the protein structural changes are intermediate between Arabidopsis phot1 and Adiantum neochrome 1. These results suggest that the conformational changes of the Jα helix and the interaction between the LOV-core and the Jα helix are different among phototropins. The role of the Jα helix for signal transduction in phototropins is discussed.