Publication Date


Document Type


Committee Members

Michael Leffak (Advisor)

Degree Name

Master of Science (MS)


The DNA unwinding element binding protein (DUE-B) was first identified by using a yeast one hybrid screen with the DNA unwinding element (DUE) from the c-myc origin as bait. DUE-B's orthologue in the yeast Saccharomyces cerevisiae lacks the last 60 C-terminal amino acids and has been identified as a D-tyrosyl-tRNA deacylase. A substantial group of evidence suggests a role for DUE-B in the regulation of replication initiation. Here we show that DUE-B is focused in nuclear speckles and colocalizes with spliceosome associated protein 145 (SAP145), an mRNA splicing factor 3B subunit. Mass spectrometry results show that SAP145 co-purifies with the 6xHis-tagged DUE-B. Surprisingly, ÄCT- DUE-B, the DUE-B mutant lacking the 60 C-terminal amino acids, appeared almost exclusively in nuclear speckles whereas its yeast orthologue was found to be cytoplasmic. DUE-B's distribution pattern did not change in cells arrested in G1/S and it did not appear in replication foci despite the strong evidence of its involvement in replication initiation. Finally, DUE-B's proposed interaction with DNA methyltransferase 1 (Dnmt1) is further investigated by immunofluorescence. Interestingly, results show that this interaction with Dnmt1 seems to occur in nuclear speckles. Based on DUE-B's interacting proteins and its concentration in nuclear speckles, a possible role in the DNA damage response is discussed.

Page Count


Department or Program

Department of Biochemistry and Molecular Biology

Year Degree Awarded