Defense Date


Document Type


Degree Name

Master of Science



First Advisor

Janina P. Lewis, Ph.D.


Proteins that bind to both DNA and RNA embody the ability to perform multiple functions by a single gene product. These nucleic acid binding proteins in prokaryotes can play a vital role in many cellular processes, including replication, transcription, gene expression, recombination, and repair, to name a few. Nucleic acid binding proteins have unique functional characteristics that stem from their structural attributes that have evolved in a widely-conserved manner. In Escherichia coli (E. coli), the highly-conserved histone-like protein, HU, which predominates as a heterodimer of HUα and HUβ, has been found to bind to both dsDNA and ssDNA. Likewise, RNA-binding proteins contain various structural motifs, many of which are also conserved amongst many bacterial species like the RNA recognition motif. However, in Porphyromonas gingivalis, a periodontal pathogen, the histone-like, HU proteins and the RNA-binding protein (RBP) are not well characterized compared to their respective structures in E. coli. In our study, we sought to characterize and compare the HU proteins and RBP in order to gain a better understanding of their structure and function in the cell. Our data showed the HU proteins predominate as homo-tetramers and RBP as a monomer. We demonstrated single-stranded DNA binding with all three proteins. We found both P. gingivalis HU subunits bind non-specifically to ssDNA but show preferential binding to poly(dG) content, while binding to poly(dA) the weakest. These results show that HUα, HUβ and RBP are novel ssDNA binding proteins in P. gingivalis, indicating an expanded role and function within the cell.


© Steve Kokorelis

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Date of Submission


Available for download on Wednesday, May 04, 2022