Maintenance of sister-chromatid cohesion at the centromere by the Drosophila MEI-S332 protein (original) (raw)

  1. Tracy Tzu-Ling Tang,
  2. Sharon E. Bickel1,
  3. Lynn M. Young2, and
  4. Terry L. Orr-Weaver3
  5. Whitehead Institute and Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts USA 02142

Abstract

Sister-chromatid cohesion is essential for the faithful segregation of chromosomes during cell division. Recently biochemical analysis with_Xenopus_ extracts suggests that cohesion is established during S phase by a cohesion complex but that other proteins must maintain it in mitosis. The Drosophila melanogaster MEI-S332 protein is present on centromeres in mitosis and meiosis and is essential for cohesion at the centromeres in meiosis II. Here, we analyze the timing of MEI-S332 assembly onto centromeres and the functional domains of the MEI-S332 protein. We find that MEI-S332 is first detectable on chromosomes during prometaphase, and this localization is independent of microtubules. MEI-S332 contains two separable functional domains, as mutations within these domains show intragenic complementation. The carboxy-terminal basic region is required for chromosomal localization. The amino-terminal coiled-coil domain may facilitate protein–protein interactions between MEI-S332 and male meiotic proteins. MEI-S332 interacts with itself in the yeast two-hybrid assay and in immunoprecipitates from Drosophila oocyte and embryo extracts. Thus it appears that MEI-S332 assembles into a multimeric protein complex that localizes to centromeric regions during prometaphase and is required for the maintenance of sister-chromatid cohesion until anaphase, rather than its establishment in S phase.

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