Universität zu Köln

Holtkotte, Xu, Dieterle, Stefan, Kokkelink, Leonie, Artz, Oliver, Leson, Lisa, Fittinghoff, Kirsten, Hayama, Ryosuke, Ahmad, Margaret and Hoecker, Ute ORCID: 0000-0002-5636-9777 (2016). Mutations in the N-terminal kinase-like domain of the repressor of photomorphogenesis SPA1 severely impair SPA1 function but not light responsiveness in Arabidopsis. Plant J., 88 (2). S. 205 - 219. HOBOKEN: WILEY-BLACKWELL. ISSN 1365-313X

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Abstract

The COP1/SPA complex is an E3 ubiquitin ligase that acts as a key repressor of photomorphogenesis in dark-grown plants. While both COP1 and the four SPA proteins contain coiled-coil and WD-repeat domains, SPA proteins differ from COP1 in carrying an N-terminal kinase-like domain that is not present in COP1. Here, we have analyzed the effects of deletions and missense mutations in the N-terminus of SPA1 when expressed in a spa quadruple mutant background devoid of any other SPA proteins. Deletion of the large N-terminus of SPA1 severely impaired SPA1 activity in transgenic plants with respect to seedling etiolation, leaf expansion and flowering time. This DN SPA1 protein showed a strongly reduced affinity for COP1 in vitro and in vivo, indicating that the N-terminus contributes to COP1/SPA complex formation. Deletion of only the highly conserved 95 amino acids of the kinase-like domain did not severely affect SPA1 function nor interactions with COP1 or cryptochromes. In contrast, missense mutations in this part of the kinase-like domain severely abrogated SPA1 function, suggesting an overriding negative effect of these mutations on SPA1 activity. We therefore hypothesize that the sequence of the kinase-like domain has been conserved during evolution because it carries structural information important for the activity of SPA1 in darkness. The N-terminus of SPA1 was not essential for light responsiveness of seedlings, suggesting that photoreceptors can inhibit the COP1/SPA complex in the absence of the SPA1 N-terminal domain. Together, these results uncover an important, but complex role of the SPA1 N-terminus in the suppression of photomorphogenesis.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Holtkotte, Xu UNSPECIFIED UNSPECIFIED UNSPECIFIED Dieterle, Stefan UNSPECIFIED UNSPECIFIED UNSPECIFIED Kokkelink, Leonie UNSPECIFIED UNSPECIFIED UNSPECIFIED Artz, Oliver UNSPECIFIED UNSPECIFIED UNSPECIFIED Leson, Lisa UNSPECIFIED UNSPECIFIED UNSPECIFIED Fittinghoff, Kirsten UNSPECIFIED UNSPECIFIED UNSPECIFIED Hayama, Ryosuke UNSPECIFIED UNSPECIFIED UNSPECIFIED Ahmad, Margaret UNSPECIFIED UNSPECIFIED UNSPECIFIED Hoecker, Ute UNSPECIFIED orcid.org/0000-0002-5636-9777 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-259263
DOI:	10.1111/tpj.13241
Journal or Publication Title:	Plant J.
Volume:	88
Number:	2
Page Range:	S. 205 - 219
Date:	2016
Publisher:	WILEY-BLACKWELL
Place of Publication:	HOBOKEN
ISSN:	1365-313X
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 COP1 E3 LIGASE; FAR-RED LIGHT; BLUE-LIGHT; DEPENDENT INTERACTION; SIGNAL-TRANSDUCTION; PROTEIN STABILITY; FLOWERING TIME; CRYPTOCHROME 1; REPEAT DOMAIN; PLANT-GROWTH Multiple languages Plant Sciences Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/25926