Characterization of the GINS subunit psf1 in Drosophila Melanogaster
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Date
2010
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Authors
Sufrinko, Brian
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Publisher
East Carolina University
Abstract
GINS (Go Ichi Ni San; 5,1,2,3 in Japanese) is a heterotetrameric protein complex known to be essential for the establishment of DNA replication forks and the progression of the replisome. The GINS complex is known to be integral in G1 to S phase transition. GINS may play a role in loading Cdc45 and DNA polymerases [alpha] and [epsilon] and has been suggested to function in the activation of the MCM helicase. The Psf1 subunit of the GINS complex is evolutionarily conserved and has been identified in all sequenced eukaryotic genomes. It has been inferred that Psf1 is required for an early step in DNA replication and the binding of Cdc45. What has been discovered of the Psf1 subunit would indicate an important role DNA replication and viability of the organism. Due to the pivotal role of GINS, we investigated the functional characteristics of Psf1 along with any protein interactions. Understanding Psf1 will give a better understanding of the GINS complex as a whole and possibly reveal its role in the initiation of DNA replication and other important cellular processes. Our research has focused on a Drosophila psf1 hypomorphic allele. Our project has involved investigating the function of Psf1 using several approaches. First, we explored genetic interactions using a mutant allele of Psf1 in combination with mutant alleles for genes involved in DNA replication. Second, we determined the level of decrease in mRNA of the hypomorphic allele using reverse transcriptase PCR. Third, we used confocal microscopy to analyze the morphology and segregation of chromosomes in different tissues. Confocal microscopy was also used to assess any cell cycle defects through the measurement of mitotic indices. Lastly, we created a true null psf1 mutant allele for further research.