Regulation of centromere localization of the Drosophila Shugoshin MEI-S332 and sister-chromatid cohesion in meiosis.
Bottom Line: These studies also suggested that MEI-S332 can be inactivated independently of delocalization, a conclusion supported here by localization and function studies in meiosis.Phosphoresistant and phosphomimetic mutants for the Aurora B and Polo phosphorylation sites were examined for effects on MEI-S332 localization and chromosome segregation in meiosis.Strikingly, MEI-S332 with a phosphomimetic mutation in the Aurora B phosphorylation site prematurely dissociates from the centromeres in meiosis I.
Affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142.Show MeSH
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Mentions: A phosphomimetic version of the Polo box-binding domain was made in which T331 was replaced with aspartic acid (T331-D). In vitro binding studies with Polo (see File S1) showed that this form of MEI-S332 exhibited enhanced binding to Polo (Figure S3). The behavior of MEI-S332-GFPT331-D was examined in transgenic lines as for the other MEI-S332 phosphomutants (Figure 5). In metaphase I, the protein localized to centromeres in 60% of spermatocytes, but in the remaining spermatocytes, weak arm localization was present. The majority of anaphase I cells lacked detectable MEI-S332 on the chromosomes. Nearly all metaphase II cells showed weak staining for MEI-S332 along the chromosomes. Thus, the T331-D mutation reduces centromere localization of MEI-S332, instead there are low levels of protein binding along the chromosome arms.
Affiliation: Whitehead Institute, Massachusetts Institute of Technology, Cambridge, Massachusetts 02142.