An extragenic suppressor of the mitosis-defective bimD6 mutation of Aspergillus nidulans codes for a chromosome scaffold protein.
We previously identified a gene, bimD, that functions in chromosome segregation and contains sequences suggesting that it may be a DNA-binding protein. Two conditionally lethal mutations in bimD arrest with aberrant mitotic spindles at restrictive temperature. These spindles have one-third the normal number of microtubules, and the chromosomes never attach to the remaining microtubules. For this reason, we hypothesized that BIMD functioned in chromosome segregation, possibly as a component of the kinetochore. To identify other components that function with bimD, we conducted a screen for extragenic suppressors of the bimD5 and bimD6 mutations. We have isolated seven cold-sensitive extragenic suppressors of bimD6 heat sensitivity that represent three or possibly four separate sud genes. We have cloned one of the suppressor genes by complementation of the cold-sensitive phenotype of the sudA3 mutation. SUDA belongs to the DA-box protein family. DA-box proteins have been shown to function in chromosome structure and segregation. Thus bimD and the sud genes cooperatively function in chromosome segregation in Aspergillus nidulans.
Holt
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Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030, USA.
May
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GS
D000483:Alleles; D000595:Amino Acid Sequence; D001233:Aspergillus nidulans / Q000235:genetics*; D018797:Cell Cycle Proteins; D002467:Cell Nucleus; D002842:Chromatids; D015825:Chromosomes, Fungal; D004249:DNA Damage; D005656:Fungal Proteins / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D008938:Mitosis / Q000502:physiology*; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics*
C083254:BIMD protein, Emericella nidulans; D018797:Cell Cycle Proteins; D005656:Fungal Proteins; D012097:Repressor Proteins