Novel sfi1 alleles uncover additional functions for Sfi1p in bipolar spindle assembly and function.
A variety of spindle and kinetochore defects have been shown to induce a mitotic delay through activation of the spindle checkpoint. With the aim of identifying novel mitotic defects we carried out a mad1 synthetic lethal screen in budding yeast. In this screen, four novel alleles of sfi1 were isolated. SFI1 is an essential gene, previously identified through its interaction with centrin/CDC31 and shown to be required for spindle pole body (SPB) duplication. The new mutations were all found in the C-terminal domain of Sfi1p, which has no known function, but it is well conserved among budding yeasts. Analysis of the novel sfi1 mutants, through a combination of light and electron microscopy, revealed duplicated SPBs <0.3 microm apart. Importantly, these SPBs have completed duplication, but they are not separated, suggesting a possible defect in splitting of the bridge. We discuss possible roles for Sfi1p in this step in bipolar spindle assembly.
Anderson
Victoria E
VE
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Edinburgh EH9 3JR, United Kingdom.
Prudden
John
J
Prochnik
Simon
S
Giddings
Thomas H
TH
Hardwick
Kevin G
KG
D000483:Alleles; D000595:Amino Acid Sequence; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D008941:Spindle Apparatus / Q000378:metabolism* / Q000648:ultrastructure
D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D012097:Repressor Proteins; C121820:SFI1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins