Mol Biol Cell. 2010 Jun 1;21(11):1799-809. doi: 10.1091/mbc.e09-05-0392. Epub 2010 Apr 7.
A period of pairing between nonhomologous centromeres occurs early in meiosis in a diverse collection of organisms. This early, homology-independent, centromere pairing, referred to as centromere coupling in budding yeast, gives way to an alignment of homologous centromeres as homologues synapse later in meiotic prophase. The regulation of centromere coupling and its underlying mechanism have not been elucidated. In budding yeast, the protein Zip1p is a major component of the central element of the synaptonemal complex in pachytene of meiosis, and earlier, is essential for centromere coupling. The experiments reported here demonstrate that centromere coupling is mechanistically distinct from synaptonemal complex assembly. Zip2p, Zip3p, and Red1p are all required for the assembly of Zip1 into the synaptonemal complex but are dispensable for centromere coupling. However, the meiotic cohesin Rec8p is required for centromere coupling. Loading of meiotic cohesins to centromeres and cohesin-associated regions is required for the association of Zip1 with these sites, and the association of Zip1 with the centromeres then promotes coupling. These findings reveal a mechanism that promotes associations between centromeres before the assembly of the synaptonemal complex, and they demonstrate that chromosomes are preloaded with Zip1p in a manner that may promote synapsis.
在多种生物中，非同源着丝粒在减数分裂早期发生配对。这种早期的、与同源性无关的着丝粒配对，在出芽酵母中被称为着丝粒连接，随后在减数分裂前期同源着丝粒发生联会。着丝粒连接的调控及其潜在机制尚未阐明。在出芽酵母中，蛋白 Zip1p 是减数分裂粗线期联会复合体中心元件的主要组成部分，而且在早期，对于着丝粒连接是必需的。这里报道的实验表明，着丝粒连接在机制上与联会复合体的组装不同。Zip2p、Zip3p 和 Red1p 都需要将 Zip1 组装到联会复合体中，但对于着丝粒连接是可有可无的。然而，减数分裂黏合蛋白 Rec8p 对于着丝粒连接是必需的。减数分裂黏合蛋白加载到着丝粒和黏合相关区域是 Zip1 与这些位点结合所必需的，然后 Zip1 与着丝粒的结合促进了连接。这些发现揭示了一种在联会复合体组装之前促进着丝粒之间关联的机制，并表明染色体以一种可能促进联会的方式预先加载了 Zip1p。
