Universität zu Köln

Chen, Song ORCID: 0000-0003-0726-7114, Wirthmueller, Lennart ORCID: 0000-0003-0667-5343, Stauber, Johannes, Lory, Niels, Holtkotte, Xu, Leson, Lisa, Schenkel, Christian, Ahmad, Margaret and Hoecker, Ute ORCID: 0000-0002-5636-9777 (2016). The functional divergence between SPA1 and SPA2 in Arabidopsis photomorphogenesis maps primarily to the respective N-terminal kinase-like domain. BMC Plant Biol., 16. LONDON: BIOMED CENTRAL LTD. ISSN 1471-2229

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Abstract

Background: Plants have evolved complex mechanisms to adapt growth and development to the light environment. The COP1/SPA complex is a key repressor of photomorphogenesis in dark-grown Arabidopsis plants and acts as an E3 ubiquitin ligase to ubiquitinate transcription factors involved in the light response. In the light, COP1/SPA activity is inhibited by photoreceptors, thereby allowing accumulation of these transcription factors and a subsequent light response. Previous results have shown that the four members of the SPA family exhibit partially divergent functions. In particular, SPA1 and SPA2 strongly differ in their responsiveness to light, while they have indistinguishable activities in darkness. The much higher light-responsiveness of SPA2 is partially explained by the much stronger light-induced degradation of SPA2 when compared to SPA1. Here, we have conducted SPA1/SPA2 domain swap experiments to identify the protein domain(s) responsible for the functional divergence between SPA1 and SPA2. Results: We have individually swapped the three domains between SPA1 and SPA2 - the N-terminal kinase-like domain, the coiled-coil domain and the WD-repeat domain - and expressed them in spa mutant Arabidopsis plants. The phenotypes of transgenic seedlings show that the respective N-terminal kinase-like domain is primarily responsible for the respective light-responsiveness of SPA1 and SPA2. Furthermore, the most divergent part of the N-terminal domain was sufficient to confer a SPA1- or SPA2-like activity to the respective SPA protein. The stronger light-induced degradation of SPA2 when compared to SPA1 was also primarily conferred by the SPA2 N-terminal domain. At last, the different affinities of SPA1 and SPA2 for cryptochrome 2 are defined by the N-terminal domain of the respective SPA protein. In contrast, both SPA1 and SPA2 similarly interacted with COP1 in light-grown seedlings. Conclusions: Our results show that the distinct activities and protein stabilities of SPA1 and SPA2 in light-grown seedlings are primarily encoded by their N-terminal kinase-like domains. Similarly, the different affinities of SPA1 and SPA2 for cry2 are explained by their respective N-terminal domain. Hence, after a duplication event during evolution, the N-terminal domains of SPA1 and SPA2 underwent subfunctionalization, possibly to allow optimal adaptation of growth and development to a changing light environment.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Chen, Song UNSPECIFIED orcid.org/0000-0003-0726-7114 UNSPECIFIED Wirthmueller, Lennart UNSPECIFIED orcid.org/0000-0003-0667-5343 UNSPECIFIED Stauber, Johannes UNSPECIFIED UNSPECIFIED UNSPECIFIED Lory, Niels UNSPECIFIED UNSPECIFIED UNSPECIFIED Holtkotte, Xu UNSPECIFIED UNSPECIFIED UNSPECIFIED Leson, Lisa UNSPECIFIED UNSPECIFIED UNSPECIFIED Schenkel, Christian UNSPECIFIED UNSPECIFIED UNSPECIFIED Ahmad, Margaret UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoecker, Ute UNSPECIFIED orcid.org/0000-0002-5636-9777 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-269688
DOI:	10.1186/s12870-016-0854-9
Journal or Publication Title:	BMC Plant Biol.
Volume:	16
Date:	2016
Publisher:	BIOMED CENTRAL LTD
Place of Publication:	LONDON
ISSN:	1471-2229
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Biology > Botanical Institute
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language LIGHT-DEPENDENT INTERACTION; BLUE-LIGHT; SIGNAL-TRANSDUCTION; GENE-EXPRESSION; FLOWERING TIME; CRYPTOCHROME 1; COP1 ACTIVITY; RED-LIGHT; PHYTOCHROME; PROTEINS Multiple languages Plant Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/26968