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Interplay of SLIM1 and miR395 in the regulation of sulfate assimilation Arabidopsis

The Plant Journal (Impact Factor: 6.82). 04/2011; 66(5):863 - 876. DOI: 10.1111/j.1365-313X.2011.04547.x

ABSTRACT MicroRNAs play a key role in the control of plant development and response to adverse environmental conditions. For example, microRNA395 (miR395), which targets three out of four isoforms of ATP sulfurylase, the first enzyme of sulfate assimilation, as well as a low-affinity sulfate transporter, SULTR2;1, is strongly induced by sulfate deficiency. However, other components of sulfate assimilation are induced by sulfate starvation, so that the role of miR395 is counterintuitive. Here, we describe the regulation of miR395 and its targets by sulfate starvation. We show that miR395 is important for the increased translocation of sulfate to the shoots during sulfate starvation. MiR395 together with the SULFUR LIMITATION 1 transcription factor maintain optimal levels of ATP sulfurylase transcripts to enable increased flux through the sulfate assimilation pathway in sulfate-deficient plants. Reduced expression of ATP sulfurylase (ATPS) alone affects both sulfate translocation and flux, but SULTR2;1 is important for the full rate of sulfate translocation to the shoots. Thus, miR395 is an integral part of the regulatory circuit controlling plant sulfate assimilation with a complex mechanism of action.

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Available from: Stanislav Kopriva, Feb 19, 2014
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    • "Recent findings indicate that ATPS gene expression in A. thaliana is, at least in part, controlled post-transcriptionally by the miR395 family of micro-RNAs (miRNAs, non-coding short RNAs), whose production is induced by sulfate deprivation (Jones-Rhoades and Bartel, 2004; Allen et al., 2005; Kawashima et al., 2011). miR395 is regulated by SLIM1 (Kawashima et al., 2011), a transcription factor responsible of the regulation of sulfate transporters SULTR1;1, −1;2, −3;4, and −4;2 and of ATPS4 "
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    ABSTRACT: ATP sulfurylase (ATPS) catalyzes the first committed step in the sulfate assimilation pathway, the activation of sulfate prior to its reduction. ATPS has been studied in only a few model organisms and even in these cases to a much smaller extent than the sulfate reduction and cysteine synthesis enzymes. This is possibly because the latter were considered of greater regulatory importance for sulfate assimilation. Recent evidences (reported in this paper) challenge this view and suggest that ATPS may have a crucial regulatory role in sulfate assimilation, at least in algae. In the ensuing text, we summarize the current knowledge on ATPS, with special attention to the processes that control its activity and gene(s) expression in algae. Special attention is given to algae ATPS proteins. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPS revealed that the algal enzymes, especially those that are most likely involved in the pathway of sulfate reduction to cysteine, possess features that are not present in other organisms. Remarkably, algal ATPS proteins show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. According to the occurrence of cysteine residues, the ATPS of eukaryotic algae is closer to that of marine cyanobacteria of the genera Synechococcus and Prochlorococcus and is more distant from that of freshwater cyanobacteria. These characteristics might have evolved in parallel with the radiation of algae in the oceans and the increase of sulfate concentration in seawater.
    Frontiers in Plant Science 11/2014; 5:597. DOI:10.3389/fpls.2014.00597 · 3.95 Impact Factor
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    • "Recent findings indicate that ATPS gene expression in A. thaliana is, at least in part, controlled post-transcriptionally by the miR395 family of micro-RNAs (miRNAs, non-coding short RNAs), whose production is induced by sulfate deprivation (Jones-Rhoades and Bartel, 2004; Allen et al., 2005; Kawashima et al., 2011). miR395 is regulated by SLIM1 (Kawashima et al., 2011), a transcription factor responsible of the regulation of sulfate transporters SULTR1;1, −1;2, −3;4, and −4;2 and of ATPS4 "
    Frontiers in Plant Science 11/2014; 5:597. · 3.95 Impact Factor
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    • "During sulfur deficiency the concentration of O-acetylserine, the precursor of cysteine increases which ultimately increases the level of miR395. The transcription factor Sulfur Limitation 1 (SLIM1) also interacts with miR395 and thus increases sulfate assimilation (Kawashima et al. 2011). In addition to the already known targets of miR395 (AST68, APS1, APS3 and APS4), another target At2g28780 was identified. "
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    ABSTRACT: Key message Small RNAs that are highly conserved across many plant species are involved in stress responses. Abstract Plants are exposed to many types of unfavorable conditions during their life cycle that result in some degree of stress. Recent studies on microRNAs (miRNAs) have highlighted their great potential as regulators of stress tolerance in plants. One of the possible ways in which plants counter environmental stresses is by altering their gene expression by the action of miRNAs. miRNAs regulate the expression of target genes by hybridizing to their nascent reverse complementary sequences marking them for cleavage in the nucleus or translational repression in the cytoplasm. Some miRNAs have been reported to be key regulators in biotic as well as abiotic stress responses across many species. The present review highlights some of the regulatory roles of orthologous plant miRNAs in response to various types of stress conditions.
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