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A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin.

ABSTRACT: Plants sense their environmental light conditions by using three photoreceptors that absorb in the UV, blue/near UV, and red/far-red spectral ranges. These photoreceptors have specific chromophore components corresponding to their absorption spectra. Phytochrome, a red/far-red light receptor, has phytochromobilin as its chromophore, whereas the blue/near UV photoreceptors cryptochrome and phototropin have a pair of flavin derivatives. Plants use these various photoreceptors to assess the surrounding light environment. Phytochrome 3 (PHY3) is a red light receptor found in some ferns, which preferentially grow under weak light. PHY3 is composed of a phytochrome chromophore-binding domain in its N-terminal portion and an almost full-length phototropin in its C-terminal half. This unusual domain organization implies that two different light-sensing systems coexist in this single photoreceptor, although these light-sensing systems usually reside in independent photoreceptors. Here, we show that PHY3 acts as a dual-channel photoreceptor that possesses both the red light-sensing system of phytochrome and the blue light-sensing system of phototropin. Furthermore, red- and blue-light signals perceived by PHY3 are processed synergistically within this single chromoprotein. These unusual properties might confer an enhanced light sensitivity on PHY3, allowing ferns to grow under a low-light canopy.

SUBMITTER: Kanegae T

PROVIDER: S-EPMC1693861 | biostudies-other | 2006 Nov

REPOSITORIES: biostudies-other

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A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin.

Kanegae Takeshi T Hayashida Emi E Kuramoto Chihiro C Wada Masamitsu M

Proceedings of the National Academy of Sciences of the United States of America 20061108 47

Plants sense their environmental light conditions by using three photoreceptors that absorb in the UV, blue/near UV, and red/far-red spectral ranges. These photoreceptors have specific chromophore components corresponding to their absorption spectra. Phytochrome, a red/far-red light receptor, has phytochromobilin as its chromophore, whereas the blue/near UV photoreceptors cryptochrome and phototropin have a pair of flavin derivatives. Plants use these various photoreceptors to assess the surroun ...[more]

PMID: 17093054

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Dataset Information

A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin.

Publications

A single chromoprotein with triple chromophores acts as both a phytochrome and a phototropin.

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