The PR-1a promoter contains a number of elements that bind GT-1-like nuclear factors with different affinity

Abstract

The 900 bp promoter region of the tobacco PR-1a gene was divided into eight fragments using PCR. The fragments were tested for their ability to bind to nuclear factors isolated from tobacco leaf. Band shift assays demonstrated that all but one of the fragments specifically interacted with nuclear proteins. From competition experiments it was determined that the same nuclear factors bind various promoter fragments with different affinity. Moreover, efficient competition with a synthetic tetramer of box II of the rbcS promoter indicated that GT-1-like nuclear factors are involved in these interactions. Furthermore, in comparison to extracts from untreated plants, nuclear protein preparations from tobacco mosaic virus-infected tobacco showed a reduced GT-1 binding activity. These results will be discussed in relation to induced PR-1a gene expression.

Ancestral Multipartite Units in Light-Responsive Plant Promoters Have Structural Features Correlating with Specific Phototransduction Pathways

“…This new analysis revealed that many of the identified LRE-associated CMAs are phylogenetically related. For instance, apparently unrelated cis-acting elements such as the X-and Y-boxes from the Lemna rbcS genes (Buzby et al, 1990) and the I-and G-box elements from the Solanaceae rbcS-CMA5 (I-G unit), seem to be evolutionarily derived from the same ancestral regulatory promoter region (Fig. 5A).…”

“…lightspecific) components of PhANG LREs: (a) two elements from cab genes that have been unequivocally defined as responsive to phytochrome-derived signals, namely the CGF-1 cognate site and the LS7 element, contain IB-like motifs Anderson and Kay, 1995); (b) the IB is the only regulatory sequence common to monocotyledon and rbcS genes that has been shown to be involved in their regulation by light (Rolfe and Tobin, 1991;Schafner and Sheen, 1991); (c) most (if not all) of the known plant nuclear factors in which relative concentration and/ or phosphorylation state are modulated by light bind to IB/ LAMP-related sequences; they include the LRF-1 (Buzby et al, 1990), GAF-1 , 3AF3 and 3AF5 (Sarokin and Chua, 1992), and IBF-la (Borello et al, 1993) factors; (d) in vivo methylation interference experiments showed light-modulated changes in methylation patterns around the IB-like "motif 15" (rbcS-CMA2) from tomato rbcS 3 B (Manzara et al, 1991); (e) the only light-induced DNase-I hypersensitive site found in the pea rbcS3.6 promoter was centered around the IB element (Gorz et al, 1988); and (f) the presence of IB / LAMP-related sequences is the only structural feature that is shared by a11 of the known photoresponsive regions from PhANG promoters.…”

“…However, several studies have shown that deletion or mutation of GT-1 sites do not affect the photoresponsiveness of some PhANG promoters (reviewed by Terzaghi and Cashmore, 1995), and it has been established that GT-1 elements that were found in bean chs25 and rice phyA promoters function as silencers and constitutive activating elements, respectively (Lawton et al, 1991;Dehesh et al, 1992). Moreover, it has been reported that GT-1-like factors interact with nonphotoresponsive promoters (Buchel et al, 1996). Direct evidence of the participation of the GT-1 sites in lightregulatory processes have been obtained only in the case of pea rbcS box 11, a 14-bp element considerably larger than the defined 6-bp GT-1 core consensus (GGTTAA, and that is a modular component of the rbcS-CMA3.…”

A Novel WRKY Transcription Factor Is Required for Induction of PR-1a Gene Expression by Salicylic Acid and Bacterial Elicitors

“…The observation that the level of GT-1 decreased after infection of tobacco with TMV suggested a negative role of GT-1 in regulation of PR1a expression. However, mutation of the GT-1 binding sites did not affect promoter activity (Buchel et al, 1996). In this article, we used the yeast one-hybrid system to identify tobacco proteins interacting with fragments of the PR-1a promoter.…”

A promoter region that controls basal and elicitor-inducible expression levels of the NADPH:cytochrome P450 reductase gene (Cpr ) from Catharanthus roseus binds nuclear factor GT-1

“…Functional redundancy is a common property of promoter sequences and is also observed in, among others, the C. roseus Tdc and Str1 promoters (Pasquali 1994;Ouwerkerk 1997) and in the pea Rbcs-3A promoter (Kuhlemeier et al 1987). In vitro binding of GT-1 to elements with functional roles has previously been found for genes such as the pea RbcS-3A gene Kuhlemeier et al 1988;Lam and Chua 1990), and a number of defence-related genes, including the bean Chs15 gene (Lawton et al 1991), the tobacco PR-1 gene (Buchel et al 1996) and the C. roseus Tdc (Ouwerkerk 1997) and Str1 (Pasquali 1994) genes. A role for GT-1 in photoregulation has also been proposed (Kuhlemeier et al 1988;Lam and Chua 1990).…”