Article

The key enzyme of sulfate assimilation, adenosine 5′-phosphosulfate reductase, is regulated by HY5 in Arabidopsis

Department of Metabolic Biology, John Innes Centre, Norwich Research Park, Norwich NR4 7UH, UK.
The Plant Journal (Impact Factor: 5.97). 05/2011; 67(6):1042-54. DOI: 10.1111/j.1365-313X.2011.04656.x
Source: PubMed

ABSTRACT

Plant sulfate assimilation is regulated by demand for reduced sulfur, as is its key enzyme, adenosine 5'-phosphosulfate reductase (APR). In a genetic screen for mutants lacking this regulation, we identified the bZIP transcription factor LONG HYPOCOTYL 5 (HY5) as a necessary component of the regulatory circuit. Regulation of APR activity by the inhibitor of glutathione synthesis, buthionine sulfoximine, or by the precursor of cysteine, O-acetylserine, was disrupted in the hy5 mutant. When dark-adapted plants were re-illuminated, the rapid induction of APR1 and APR2 mRNA levels was attenuated in hy5 seedlings, but APR3 regulation was not affected. Chromatin immunoprecipitation revealed that HY5 binds directly to the APR1 and APR2 promoters but not to the APR3 promoter. Accordingly, the regulation of APR1 and APR2 by O-acetylserine was disturbed in hy5 roots. HY5 is also important for the coordination of nitrogen and sulfur assimilation, as, unlike the wild-type, hy5 mutants do not undergo a reduction in sulfate uptake and APR activity during nitrogen starvation. Altogether, these data show that HY5 plays an important role in regulation of APR gene expression and plant sulfate assimilation.

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Available from: Stanislav Kopriva, Feb 18, 2014
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    • "For most of the pivotal functions of sulfur in plants, the oxidized sulfur in sulfate must be reduced and assimilated to cysteine by plants before entering other metabolic processes. Sulfate uptake, reduction, and assimilation are highly regulated (Hell and Wirtz, 2011; Takahashi et al., 2011) and key regulators have been identified (Kawashima et al., 2011; Lee et al., 2011) Plastids, and especially chloroplasts, are the main site of reductive assimilation of sulfate in plants (Takahashi et al., 2011). How sulfate is transported into chloroplasts remains unresolved so far. "
    Dataset: tpj12059

    Full-text · Dataset · Dec 2014
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    • "For most of the pivotal functions of sulfur in plants, the oxidized sulfur in sulfate must be reduced and assimilated to cysteine by plants before entering other metabolic processes. Sulfate uptake, reduction, and assimilation are highly regulated (Hell and Wirtz, 2011; Takahashi et al., 2011) and key regulators have been identified (Kawashima et al., 2011; Lee et al., 2011) Plastids, and especially chloroplasts, are the main site of reductive assimilation of sulfate in plants (Takahashi et al., 2011). How sulfate is transported into chloroplasts remains unresolved so far. "
    Dataset: tpj12059

    Full-text · Dataset · Dec 2014
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    • "From this, and several qualitative studies (Tsakraklides et al., 2002; Loudet et al., 2007), the hypothesis arose that APR is the key enzyme, controlling flux through the reductive assimilation pathway (Vauclare et al., 2002; Yoshimoto et al., 2007; Davidian and Kopriva, 2010; Scheerer et al., 2010). Consistent with this idea, APR has been shown to be highly regulated by demand for reduced sulfur products (Lappartient et al., 1999; Kopriva, 2006; Davidian and Kopriva, 2010; Takahashi et al., 2011), internal sulfate levels (Lee et al., 2012), and other environmental signals (Jost et al., 2005; Koprivova et al., 2008; Lee et al., 2011; Huseby et al., 2013). More recently, however, a number of different enzymes have also been implicated in altered flux through the sulfur reduction pathway; Khan et al. (2010) found that SiR knockdown plants have a strongly reduced flux to thiols, variation in ATPS has been shown to cause altered flux of sulfur into primary metabolism (Koprivova et al., 2013), and reduction in APK increased flux through primary "
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    Full-text · Article · Nov 2014 · Frontiers in Plant Science
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