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A regulator of nutritional copper signaling in Chlamydomonas is an SBP domain protein that recognizes the GTAC core of copper response element

Lookup NU author(s): Dr Stephen Tottey


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The CRR1 (Copper Response Regulator) locus, required for both activating and repressing target genes of a copper- and hypoxia-sensing pathway in Chlamydomonas, encodes a 1,232-residue candidate transcription factor with a plant-specific DNA-binding domain named SBP, ankyrin repeats, and a C-terminal Cys-rich region, with similarity to a Drosophila metallothionein. The recombinant SBP domain of Crr1 shows zinc-dependent binding to functionally defined copper-response elements associated with the CYC6 and CPX1 promoters that contain a critical GTAC core sequence. Competition experiments indicate equivalent selectivity for copper-response elements from either promoter and 10-fold greater selectivity for the wild-type sequence vs. a sequence carrying a single mutation in the GTAC core. The SBP domain of Chlamydomonas Crr1 binds also to a related GTAC-containing sequence in the Arabidopsis AP1 promoter that is the binding site of a defining member of the SBP family of DNA-binding proteins. Chlamydomonas Crr1 is most similar to a subset of the Arabidopsis SBP domain proteins, which include SPL1, SPL7, and SPL12. The abundance of the CRR1 mRNA is only marginally copper-responsive, and although two mRNAs that differ with respect to splicing of the first intron are detected, there is no indication that the splicing event is regulated by metal nutrition or hypoxia. It is likely that the dramatic copper-responsive action of Crr1 occurs at the level of the polypeptide. © 2005 by The National Academy of Sciences of the USA.

Publication metadata

Author(s): Kropat J, Tottey S, Birkenbihl RP, Depege N, Huijser P, Merchant S

Publication type: Article

Publication status: Published

Journal: Proceedings of the National Academy of Sciences of the United States of America

Year: 2005

Volume: 102

Issue: 51

Pages: 18730-18735

Print publication date: 20/12/2005

ISSN (print): 0027-8424

ISSN (electronic): 1091-6490

Publisher: National Academy of Sciences


DOI: 10.1073/pnas.0507693102

PubMed id: 16352720


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