Student Major
Cell and Molecular Biology Chemistry
Presentation Abstract or Description
Bacteriophage exclusion (BREX) is a relatively uncharacterized 6-gene phage restriction system found in a wide range of bacteria that performs two main activities: methylation of host DNA and phage restriction. It is currently unknown how BREX genes are regulated. We have identified a seventh gene that is associated with a subset of BREX systems, BrxR, that likely transcriptionally regulates the BREX system it is linked to. Biochemical and crystallographic analyses demonstrate that BrxR forms a homodimer and specifically binds a DNA target site upstream of its transcription start site using its wHTH domains. Additional examination of the protein’s structure shows an abundance of polar groups in the WYL domain, which is located opposite the wHTH domain. We speculate that this region of BrxR functions as a sensor for phage infections by recognizing an unknown ligand produced during a phage infection, which could then induce a conformational change that alters DNA binding. We have attempted to determine the identity of the ligand by analyzing crystallographic data. Additionally, recent studies have shown that BrxR is not exclusive to BREX systems, but rather associates with various defense systems encoded within different bacterial genomes. We became interested in two highly related BrxR homologs that differ by only seven residues but bind with disparate affinities to their common DNA target. Here we test the contribution of the differing amino acids to DNA binding by systematically mutating these various positions. We hope that determining the significant amino acid positions that contribute to DNA binding will inform how BrxR DNA recognition occurs and how the BREX gene expression is regulated.
Presentation Format
Poster
Conference Name
DiscoverBMB 2024
Conference Date(s) and Location
March 23-26, 2024 in San Antonio, TX
Faculty Mentor
Brett Kaiser
Quarter Award Was Given
Winter 2024
Document Type
Article
Recommended Citation
Peralta Acosta, Julieta, "Testing the behavior of a WYL domain protein as a transcriptional regulator for the BREX phage restriction system" (2024). Undergraduate Student Conference Travel Award. 5.
https://scholarworks.seattleu.edu/travel-award/5