A Novel Plant Cysteine Protease Has a Dual Function as a Regulator of 1-Aminocyclopropane-1-Carboxylic Acid Synthase Gene Expression

Abstract

The hormone ethylene influences plant growth, development, and some defense responses. The fungal elicitor Ethylene-Inducing Xylanase (EIX) elicits ethylene biosynthesis in tomato (Lycopersicon esculentum) and tobacco (Nicotiana tabacum) leaves by induction of 1-aminocyclopropane-1-caboxylic acid synthase (Acs) gene expression. A minimal promoter element in the LeAcs2 gene required for EIX responsiveness was defined by deletion analysis in transgenic tomato plants. The sequence between −715 and −675 of the tomato Acs2 gene was found to be essential for induction by EIX. A Cys protease (LeCp) was isolated that specifically binds to this cis element in vitro. Ectopic expression of LeCp in tomato leaves induced the expression of Acs2. Moreover, chromatin immunoprecipitation showed that LeCp binds in vivo to the Acs promoter. We propose a mechanism for the dual function of the LeCp protein. The protease acts enzymatically in the cytoplasm. Then, upon signaling, a small ubiquitin-related modifier protein binds to it, enabling entrance into the nucleus, where it acts as a transcription factor. Thus, LeCp can be considered a dual-function protein, having enzymatic activity and, upon elicitor signaling, exhibiting transcriptional factor activity that induces LeAcs2 expression.

Transcriptional Regulation of the Ethylene Response Factor LeERF2 in the Expression of Ethylene Biosynthesis Genes Controls Ethylene Production in Tomato and Tobacco

“…Accumulated evidence shows that the expression of ACS and ACO is induced by various factors, including indole-3-acetic acid, physical injury, cytokinins, ABA, brassinosteroid, ethylene, and other forms of stress (Tsuchisaka and Theologis, 2004;Wang et al, 2005;Hansen et al, 2009). A growing number of studies have reported that multiple regulations are involved in the expression of ACS and ACO (Matarasso et al, 2005;Ito et al, 2008;Lin et al, 2008). For example, tomato LeCp is a dual-function protein that acts as a Cys protease in the cytoplasm and can be SUMO modified to enter the nucleus to directly activate the expression of tomato LeACS2 following attack by a pathogen (Matarasso et al, 2005).…”

“…A growing number of studies have reported that multiple regulations are involved in the expression of ACS and ACO (Matarasso et al, 2005;Ito et al, 2008;Lin et al, 2008). For example, tomato LeCp is a dual-function protein that acts as a Cys protease in the cytoplasm and can be SUMO modified to enter the nucleus to directly activate the expression of tomato LeACS2 following attack by a pathogen (Matarasso et al, 2005). The MADS box transcription factor RIN plays an important role in regulating the expression of Figure 5.…”

“…Stresses such as cold, drought, and salt also induce high levels of ACS transcripts, the level of which is associated with the amount of ethylene production (Wang et al, 2002;Achard et al, 2006). Matarasso et al (2005) demonstrated that tomato Cys protease, LeCP, when pathogenically induced, regulates the expression of LeACS2 by directly binding to the LeACS2 promoter. Recently, Lin et al (2008) found that an HD-Zip homeobox protein, LeHB-1, can bind to the homeobox cis-elements of the tomato LeACO1 promoter and regulate the gene's expression in developing fruits (Lin et al, 2008).…”

PA, a stress-induced short cut to switch-on ethylene signalling by switching-off CTR1?

“…Alternatively, PA dependent inhibition of CTR1 could function synergistically with ethylene and work to promote rapid and/ or heightened activation of ethylene responses. This mechanism could act in parallel with other recently described stress-activated pathways that induce ethylene production through induction of ACC synthase (ACS) gene expression 16 and ACS activity. 12 An advantage of the PA pathway would be its speed.…”

An Extended AE-Rich N-Terminal Trunk in Secreted Pineapple Cystatin Enhances Inhibition of Fruit Bromelain and Is Posttranslationally Removed during Ripening

“…5, D-F). As described for other diverse tissues and fruits (Soda et al, 1986;Alonso and Cranell, 1995;Itai et al, 2000;Matarasso et al, 2005), Cys proteases of the secretory pathway are required during ripening and senescence for the degradation and recycling of proteins (Solomon et al, 1999;Matarasso et al, 2005;Ondzighi et al, 2008). Fruit bromelain contains a strong signal peptide (http://www.uniprot.…”