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Sequence similarities between the yeast chromosome segregation protein Mif2 and the mammalian centromere protein
1Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA 98104, USA.
Abstract:
A short stretch of strong homology between the Saccharomyces cerevisiae chromosome segregation protein Mif2 and the DNA-binding motifs of the Drosophila D1 and mammalian HMGI(Y) chromosomal proteins suggested that Mif2 may act directly on chromosomes. Because this conserved motif is involved in binding A.T DNA, it was proposed that Mif2 may interact with chromosomes at the highly A + T-rich DNA element found in yeast centromeres. Comparison of the Mif2 amino-acid sequence with sequence databases showed that Mif2 shares at least two regions of similarity with the mammalian centromere protein CENP-C, suggesting an evolutionary conservation of centromere protein function from yeast to mammals. The order, spacing and location of these regions are also similar in the two proteins. Sequence analysis of several conditional lethal alleles of MIF2 generated by random mutagenesis revealed mutations in regions homologous to CENP-C, as well as in the highly conserved A.T DNA-binding motif. A potential phosphorylation site for p34cdc2 kinase located adjacent to the A.T DNA-binding motif was also found to be mutated in one of the mutants, suggesting that phosphorylation at this site may be important for Mif2 function and possibly for DNA binding.
Insights
The yeast chromosome segregation protein Mif2 shares similarities with mammalian centromere protein CENP-C, suggesting conserved function. Mutations in Mif2 highlight its role in DNA binding and potential phosphorylation regulation.
Area of Science:
- Molecular Biology
- Genetics
- Cell Biology
Background:
- The Saccharomyces cerevisiae chromosome segregation protein Mif2 exhibits homology with DNA-binding motifs of Drosophila D1 and mammalian HMGI(Y) proteins.
- This homology suggests a potential direct interaction of Mif2 with chromosomes, particularly at A.T-rich DNA elements in yeast centromeres.
Purpose of the Study:
- To investigate the functional and evolutionary conservation of the yeast Mif2 protein.
- To identify specific regions and mechanisms involved in Mif2's interaction with chromosomes and its role in centromere function.
Main Methods:
- Sequence homology comparisons between Mif2 and known DNA-binding and centromere proteins.
- Sequence analysis of conditional lethal alleles of MIF2 generated through random mutagenesis.
Main Results:
- Mif2 shares significant sequence similarity with mammalian centromere protein CENP-C, indicating evolutionary conservation from yeast to mammals.
- Mutations in MIF2 alleles were found in regions homologous to CENP-C and the A.T DNA-binding motif.
- A potential p34cdc2 kinase phosphorylation site adjacent to the A.T DNA-binding motif was mutated in one allele.
Conclusions:
- Mif2 likely interacts with chromosomes via its conserved DNA-binding motif and shares functional and structural similarities with mammalian CENP-C.
- Phosphorylation at the identified site may be crucial for Mif2 function and DNA binding, suggesting a regulatory mechanism.