Nucleotide sequence comparisons and functional analysis of yeast centromere DNAs

Area of Science:

• Molecular Biology
• Genetics
• Yeast Biology

Background:

• Centromeres are essential for chromosome segregation during cell division.
• Understanding centromere structure is key to comprehending genome stability.
• Yeast centromeres provide a model system for studying these fundamental genetic elements.

Purpose of the Study:

• To determine the nucleotide sequences of functional yeast centromeres (CEN3 and CEN11).
• To identify common structural features and sequence homologies between different centromeres.
• To investigate the minimal DNA fragment size required for centromere function.

Main Methods:

• Isolation and nucleotide sequencing of DNA segments containing CEN3 and CEN11 from yeast chromosomes.
• Assay of centromere activity using mitotic stabilization of autonomously replicating plasmids (ars plasmids) in yeast.
• Bioinformatic analysis of sequence homologies.

Main Results:

• The nucleotide sequences of CEN3 and CEN11 differ but share common structural elements.
• Both centromeres possess an A+T-rich core and conserved flanking sequences with identical spatial arrangements.
• Centromere activity was confirmed on relatively small DNA fragments (627 bp for CEN3, 858 bp for CEN11).
• Homologies were found between sequences flanking the yeast centromeres and higher eukaryote satellite DNA.

Conclusions:

• Yeast centromeres exhibit conserved structural organization despite sequence divergence.
• Specific DNA elements and their spatial arrangement are critical for centromere function.
• These findings contribute to understanding the fundamental mechanisms of chromosome segregation and genome stability.