PcMYB1, a novel plant protein containing a DNA‐binding domain with one MYB repeat, interacts in vivo with a light‐regulatory promoter unit

Abstract

SummaryLight-regulatory unit 1 (LRU1) is necessary for and sufficient to mediate light-dependent activation of the chalcone synthase (CHS) minimal promoter in Petroselinum crispum. This composite promoter unit consists of at least two distinct c/s-acting elements, designated ACE ces and MRE cHs, both of which are required for light induction. The ACGT-containing element ACE cHs interacts with common plant regulatory factors (CPRFs) which belong to the basic region/leucine zipper (bZlP) class of transcription factors. Here, we demonstrate that MRE cHs, originally identified as an in vivo DNA footprint, is a MYB recognition element. This element possesses a functional core that is essential for light responsiveness and is specifically recognized by two distantly related MYB-like proteins: MYB305 and the novel factor MYB1 from P. crispum. PcMYB1 was identified by both its specific binding to MRE cHs in vitro and recognition of MRE cHs in vivo. The deduced amino acid sequence revealed that PcMYB1 contains only one MYB-like repeat. This portion of the protein constitutes the DNA-binding domain. Mutational analysis of PcMYB1 in combination with sequence comparison suggests the presence of a helix-turn-helix structure containing a recognition helix that is sufficient for sequence-specific binding. The structure of this distinct MYB-like DNA-binding domain appears to be conserved in proteins from all three eukaryotic phyla.

Combinatorial interaction of light‐responsive elements plays a critical role in determining the response characteristics of light‐regulated promoters in Arabidopsis

“…However, in the case of light-regulated gene expression in plant cells, increasing lines of evidence have shown that a minimum of two different LREs in specific combinations are required to confer proper light induction (Degenhardt and Tobin, 1996;Feldbrugge et al, 1997;Puente et al, 1996). In a previous study, we have shown that only those promoters with paired LREs are able to respond to phytochrome-mediated low-fluence light pulses and are able to be activated in a tissue-specific manner (Puente et al, 1996).…”

“…However, some of the LREs are also present in promoters that are not light-regulated; and no single LRE has been found in all of the light-regulated promoters (Arguello-Astorga and Herrera-Estrella, 1996;Terzaghi and Cashmore, 1995). Recent studies have demonstrated that the combinatorial interaction of distinct LREs is required for the proper light responsiveness of promoters (Degenhardt and Tobin, 1996;Feldbrugge et al, 1997;Puente et al, 1996). These multiple LRE-containing promoters not only possess the ability to confer higher activities in light-grown plants over darkgrown plants, but also are capable of responding to phytochrome-mediated low-fluence light pulses and to developmental signals such as tissue specificity and chloroplast development.…”

MYB transcription factor genes as regulators for plant responses: an overview

“…PcMYB1 was identified by both its specific binding to MRE CHS in vitro and recognition of MRE CHS in vivo. The deduced amino acid sequence revealed that PcMYB1 contained only one MYB-like repeat (Feldbrugge et al 1997). Stracke et al (2010) reported that the bZIP transcriptional regulator ELONGATED HYPOCOTYL5 (HY5) was required for the transcriptional activation of the PFG1/MYB12 and PFG3/MYB111 genes under UV-B and visible light respectively.…”

The Arabidopsis Transcription Factor MYB12 Is a Flavonol-Specific Regulator of Phenylpropanoid Biosynthesis

“…An ACGT containing element (ACE) and a MYB recognition element (MRE) comprise the light regulatory unit (LRU AtCHS ), which confers responsiveness to UV-containing white light to the CHS promoter. The ACE and the MRE have been shown to be bound by basic region Leu zipper and MYB transcription factors, respectively (Armstrong et al, 1992;Feldbrü gge et al, 1997;Hartmann et al, 1998). A third cisacting element has recently been identified between the ACE and the MRE in the CHS promoter.…”