Epigenetic Regulation of the Maize Spm Transposable Element: Novel Activation of a Methylated Promoter by TnpA

Document Type

Article

Language

eng

Format of Original

11 p.

Publication Date

5-6-1994

Publisher

Elsevier

Source Publication

Cell

Source ISSN

0092-8674

Abstract

Spm is epigenetically inactivated by C-methylation near its transcription start site. We have investigated the interaction between TnpA, an autoregulatory protein that can reactivate a silent Spm, and the promoter of the element. The promoter undergoes rapid de novo methylation and inactivation in stably transformed plants, but only if it includes a GC-rich sequence downstream of the promoter. TnpA activates the inactive, methylated promoter and leads to reduced methylation. By contrast, TnpA represses the active, unmethylated Spm promoter. Only the internal DNA-binding and dimerization domains of the protein are required for repression, while activation requires an additional C-terminal sequence. TnpA is therefore a unique regulatory protein with a conventional transcriptional repressor activity and a novel ability to activate a methylated, inactive promoter.

Comments

Cell, Vol. 77, No. 3 (May 6, 1994): 427-437. DOI.

Michael Schläppi was affiliated with the Carnegie Institution of Washington at time of publication.

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