Kelsey P. Mayrand



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PriA, a replication restart protein found in bacteria, is highly conserved in almost all prokaryotes. However, it contains extra amino acid sequences in the microbe Deinococcus radiodurans. Since D. radiodurans is extremely resistant to ionizing radiation, these insertions could play a role in conferring resistance by improving the microbe's ability to continue replication after DNA is damaged. The project investigated the effects of the fifty-six amino acid insertion in the helicase domain of the PriA protein in D. radiodurans. To do this, a version of the PriA gene lacking the inserted element was cloned. The recombinant and wild type PriA proteins were over-expressed in E. coli and purified. Helicase assays were performed to compare the functions of the forms of the protein. It was hypothesized that the inserted element would enhance the helicase activity of the protein. However, helicase assays showed that the mutant unwound DNA more efficiently. This means that the inserted element inhibits the helicase activity of PriA.

Publication Date


Project Designation

Honors Thesis

Primary Advisor

Matthew E. Lopper

Primary Advisor's Department



Stander Symposium project

The Effect of the Inserted Sequence in the Helicase Domain of the Deinococcus radiodurans PriA Protein