a complex cell division machinery was present in the last common ancestor of eukaryotes一个复杂的细胞分裂机械出现在最后的真核生物的共同祖先.pdfVIP

A Complex Cell Division Machinery Was Present in the Last Common Ancestor of Eukaryotes 1 2 1,3 ´ 1,4 Laura Eme , David Moreira , Emmanuel Talla , Celine Brochier-Armanet * ´ ´ ´ 1 Laboratoire de Chimie Bacterienne – UPR CNRS 9043, Marseille, France, 2 Unite d’Ecologie, Systematique et Evolution – UMR CNRS 8079, Universite Paris-Sud, Orsay, ´ ´ ´ ´ France, 3 Universite de la Mediterranee, Marseille, France, 4 Universite de Provence, Marseille, France Abstract Background: The midbody is a transient complex structure containing proteins involved in cytokinesis. Up to now, it has been described only in Metazoa. Other eukaryotes present a variety of structures implied in the last steps of cell division, such as the septum in fungi or the phragmoplast in plants. However, it is unclear whether these structures are homologous (derive from a common ancestral structure) or analogous (have distinct evolutionary origins). Recently, the proteome of the hamster midbody has been characterized and 160 proteins identified. Methodology/Principal Findings: Using phylogenomic approaches, we show here that nearly all of these 160 proteins (95%) are conserved across metazoan lineages. More surprisingly, we show that a large part of the mammalian midbody components (91 proteins) were already present in the last common ancestor of all eukaryotes (LECA) and were most likely involved in the construction of a complex multi-protein assemblage acting in cell division. Conclusions/Significance: Our results indicate that the midbodies