Müller André H, Hansson Mats
Carlsberg Laboratory, DK-2500 Valby, Copenhagen, Denmark.
Plant Physiol. 2009 May;150(1):157-66. doi: 10.1104/pp.109.135277. Epub 2009 Jan 28.
Magnesium chelatase is the first unique enzyme of the chlorophyll biosynthetic pathway. It is composed of three gene products of which the largest is 150 kD. This protein was recently identified as an abscisic acid receptor in Arabidopsis (Arabidopsis thaliana). We have evaluated whether the barley (Hordeum vulgare) magnesium chelatase large subunit, XanF, could be a receptor for the phytohormone. The study involved analysis of recombinant magnesium chelatase protein as well as several induced chlorophyll-deficient magnesium chelatase mutants with defects identified at the gene and protein levels. Abscisic acid had no effect on magnesium chelatase activity and binding to the barley 150-kD protein could not be shown. Magnesium chelatase mutants showed a wild-type response in respect to postgermination growth and stomatal aperture. Our results question the function of the large magnesium chelatase subunit as an abscisic acid receptor.
镁螯合酶是叶绿素生物合成途径中的首个独特酶。它由三种基因产物组成,其中最大的为150 kD。该蛋白最近被鉴定为拟南芥中的脱落酸受体。我们评估了大麦(Hordeum vulgare)镁螯合酶大亚基XanF是否可能是这种植物激素的受体。该研究涉及对重组镁螯合酶蛋白以及几个在基因和蛋白质水平上鉴定出缺陷的诱导叶绿素缺乏型镁螯合酶突变体的分析。脱落酸对镁螯合酶活性没有影响,且未显示出其与大麦150-kD蛋白的结合。镁螯合酶突变体在萌发后生长和气孔开度方面表现出野生型反应。我们的结果对镁螯合酶大亚基作为脱落酸受体的功能提出了质疑。