Department of Cell and Developmental Biology, Biocenter, University of Würzburg, D-97074 Würzburg, Germany.
Proc Natl Acad Sci U S A. 2012 Oct 9;109(41):16588-93. doi: 10.1073/pnas.1206875109. Epub 2012 Sep 24.
The synaptonemal complex (SC) is a key structure of meiosis, mediating the stable pairing (synapsis) of homologous chromosomes during prophase I. Its remarkable tripartite structure is evolutionarily well conserved and can be found in almost all sexually reproducing organisms. However, comparison of the different SC protein components in the common meiosis model organisms Saccharomyces cerevisiae, Arabidopsis thaliana, Caenorhabditis elegans, Drosophila melanogaster, and Mus musculus revealed no sequence homology. This discrepancy challenged the hypothesis that the SC arose only once in evolution. To pursue this matter we focused on the evolution of SYCP1 and SYCP3, the two major structural SC proteins of mammals. Remarkably, our comparative bioinformatic and expression studies revealed that SYCP1 and SYCP3 are also components of the SC in the basal metazoan Hydra. In contrast to previous assumptions, we therefore conclude that SYCP1 and SYCP3 form monophyletic groups of orthologous proteins across metazoans.
联会复合体（SC）是减数分裂的关键结构，介导了前期 I 中同源染色体的稳定配对（联会）。其显著的三分体结构在进化上得到了很好的保守，几乎可以在所有有性生殖的生物中找到。然而，对常见减数分裂模式生物酿酒酵母、拟南芥、秀丽隐杆线虫、黑腹果蝇和小家鼠的不同 SC 蛋白成分的比较表明，它们之间没有序列同源性。这种差异挑战了 SC 仅在进化中出现一次的假说。为了探讨这个问题，我们专注于 SYCP1 和 SYCP3 的进化，这是哺乳动物的两个主要结构 SC 蛋白。值得注意的是，我们的比较生物信息学和表达研究表明，SYCP1 和 SYCP3 也是基础后生动物水螅 SC 的组成部分。与之前的假设相反，我们因此得出结论，SYCP1 和 SYCP3 在后生动物中形成了单系的同源蛋白群。
