Gao Hongbo, Sage Tammy L, Osteryoung Katherine W
Department of Plant Biology and Genetics Graduate Program, Michigan State University, East Lansing, MI 48824, USA.
Proc Natl Acad Sci U S A. 2006 Apr 25;103(17):6759-64. doi: 10.1073/pnas.0507287103. Epub 2006 Apr 14.
FZO is a dynamin-related membrane-remodeling protein that mediates fusion between mitochondrial outer membranes in animals and fungi. We identified a single FZO-like protein in Arabidopsis, FZL, a new plant-specific member of the dynamin superfamily. FZL is targeted to chloroplasts and associated with thylakoid and envelope membranes as punctate structures. fzl knockout mutants have abnormalities in chloroplast and thylakoid morphology, including disorganized grana stacks and alterations in the relative proportions of grana and stroma thylakoids. Overexpression of FZL-GFP also conferred defects in thylakoid organization. Mutation of a conserved residue in the predicted FZL GTPase domain abolished both the punctate localization pattern and ability of FZL-GFP to complement the fzl mutant phenotype. FZL defines a new protein class within the dynamin superfamily of membrane-remodeling GTPases that regulates organization of the thylakoid network in plants. Notably, FZL levels do not affect mitochondrial morphology or ultrastructure, suggesting that mitochondrial morphology in plants is regulated by an FZO-independent mechanism.
FZO是一种与发动蛋白相关的膜重塑蛋白，它介导动物和真菌中线粒体外膜之间的融合。我们在拟南芥中鉴定出一种单一的类FZO蛋白FZL，它是发动蛋白超家族中一个新的植物特异性成员。FZL定位于叶绿体，并以点状结构与类囊体膜和包膜膜相关联。fzl基因敲除突变体在叶绿体和类囊体形态上存在异常，包括基粒堆叠紊乱以及基粒类囊体和基质类囊体相对比例的改变。FZL-GFP的过表达也导致类囊体组织出现缺陷。预测的FZL GTP酶结构域中一个保守残基的突变消除了FZL-GFP的点状定位模式以及其互补fzl突变体表型的能力。FZL在调节植物类囊体网络组织的膜重塑GTP酶发动蛋白超家族中定义了一个新的蛋白类别。值得注意的是，FZL的水平不影响线粒体的形态或超微结构，这表明植物中线粒体的形态是由一种不依赖FZO的机制调节的。
