Isolation of the gene encoding yeast DNA polymerase I

Area of Science:

• Molecular Biology
• Yeast Genetics
• Enzymology

Background:

• DNA polymerase I is crucial for DNA replication and repair in yeast.
• Understanding the gene encoding DNA polymerase I is essential for studying yeast DNA replication mechanisms.

Purpose of the Study:

• To isolate and characterize the gene encoding yeast DNA polymerase I.
• To investigate the function of DNA polymerase I in yeast cell division and DNA replication.

Main Methods:

• Screening a yeast genomic DNA expression library with antibodies against yeast DNA polymerase I.
• Cloning the gene into plasmids (YEp24) for overexpression studies in yeast.
• Utilizing bacteriophage T7 promoter for expression in Escherichia coli.
• Employing gene disruption and Southern hybridization techniques to analyze gene essentiality and copy number.

Main Results:

• Successfully isolated and identified the gene encoding yeast DNA polymerase I.
• Demonstrated immunological relationship between clone-encoded protein and native DNA polymerase I.
• Observed 4- to 5-fold overproduction of polymerase activity in yeast cells harboring the cloned gene.
• Confirmed the gene's essentiality and single-copy nature in the yeast genome.
• Disruption of the gene led to defects in nuclear division and a terminal phenotype characteristic of replication mutants.

Conclusions:

• The isolated gene encodes the essential yeast DNA polymerase I.
• DNA polymerase I plays a critical role in nuclear division and DNA replication in yeast.
• This study provides a foundation for further research into yeast DNA replication fidelity and regulation.