Koch Johannes, Brocard Cécile
Department of Biochemistry and Cell Biology, University of Vienna, Max F. Perutz Laboratories, Center of Molecular Biology, Dr. Bohr-Gasse 9, A-1030 Vienna, Austria.
Biomol Concepts. 2011 Oct;2(5):353-364. doi: 10.1515/BMC.2011.031.
Separation of metabolic pathways in organelles is critical for eukaryotic life. Accordingly, the number, morphology and function of organelles have to be maintained through processes linked with membrane remodeling events. Despite their acknowledged significance and intense study many questions remain about the molecular mechanisms by which organellar membranes proliferate. Here, using the example of peroxisome proliferation, we give an overview of how proteins elongate membranes. Subsequent membrane fission is achieved by dynamin-related proteins shared with mitochondria. We discuss basic criteria that membranes have to fulfill for these fission factors to complete the scission. Because peroxisome elongation is always associated with unequal distribution of matrix and membrane proteins, we propose peroxisomal division to be non-stochastic and asymmetric. We further show that these organelles need not be functional to carry on membrane elongation and present the most recent findings concerning members of the Pex11 protein family as membrane elongation factors. These factors, beside known proteins such as BAR-domain proteins, represent another family of proteins containing an amphipathic α-helix with membrane bending activity.
细胞器中代谢途径的分隔对于真核生物的生命至关重要。因此，细胞器的数量、形态和功能必须通过与膜重塑事件相关的过程来维持。尽管它们的重要性已得到认可且受到深入研究，但关于细胞器膜增殖的分子机制仍存在许多问题。在这里，以过氧化物酶体增殖为例，我们概述了蛋白质如何使膜伸长。随后的膜分裂是由与线粒体共享的动力蛋白相关蛋白实现的。我们讨论了膜为使这些分裂因子完成切割而必须满足的基本标准。由于过氧化物酶体伸长总是与基质和膜蛋白的不均匀分布相关，我们提出过氧化物酶体分裂是非随机且不对称的。我们进一步表明，这些细胞器在进行膜伸长时不一定需要发挥功能，并展示了关于作为膜伸长因子的Pex11蛋白家族成员的最新发现。除了已知的蛋白质如BAR结构域蛋白外，这些因子代表了另一类含有具有膜弯曲活性的两亲性α螺旋的蛋白质家族。
