Characterization of the Genes for Sulfate Activation from Higher Plants

两种酶，ATP硫化酶和APS激酶，催化植物中硫酸盐的活化，从而合成对细胞功能至关重要的含硫化合物。ATP硫酰化酶同工酶分别存在于叶绿体、线粒体和细胞质中，可能在硫代谢中发挥着不同的生理作用。本研究的目的是研究同工酶的表达，以便为硫酸盐活化的控制建立分子基础。通过对酿酒酵母ATP硫化酶met3或APS激酶met14突变体的互补，从拟南芥中克隆出硫酸盐活化酶的cdna。已经分离出ATP硫化酶基因家族的四个成员和一个编码APS激酶的成员。这些cdna在拟南芥和芥菜中的表达和功能有待进一步研究。由于含硫肽在抗重金属中起着重要作用，因此我们将研究重金属暴露对ATP硫酰化酶和APS激酶表达的影响。这些研究将有助于我们进一步了解植物的代谢、生长、发育和对胁迫的反应。＊＊＊

9408031 Leustek Two enzymes, ATP sulfurylase and APS kinase, catalyze the activation of sulfate in plants leading to the synthesis of sulfur containing compounds vital for cell function. Isoenzymes of ATP sulfurylase are compartmentalized in chloroplasts, mitochondria and the cytosol, suggesting that they may play distinct physiological roles in sulfur metabolism. The objective of this research is to study the expression of the isoenzymes in order to establish a molecular basis for the control of sulfate activation. cDNAs encoding the sulfate activating enzymes were cloned from Arabidopsis thaliana by complementation of Saccharomyces cerevisiae ATP sulfurylase, met3, or APS kinase, met14, mutants. Four members of the ATP sulfurylase gene family and one encoding APS kinase have been isolated. It is proposed to further characterize these cDNAs and to study their expression and function in A. thaliana and Brassica juncea. Since sulfur-containing peptides play a significant role in resistance to heavy metals, the influence of heavy metal exposure will be investigated on expression of ATP sulfurylase and APS kinase. These studies will help advance our understanding of plant metabolism, growth, development and response to stress. ***