This research focuses on the antimicrobial activity of the mouse chemokine CCL28. In addition to their well characterized chemotactic activity, many chemokines have been shown to be antimicrobial in vitro, including the mucosally expressed chemokine CCL28. I have investigated the primary sequence features required for antimicrobial activity, salt sensitive nature of killing/binding mechanism, and in vivo microbial interactions of CCL28. Through the use of protein mutation and expression techniques, I have shown that the holoprotein (108 amino acids) is necessary for full antimicrobial activity of CCL28. Furthermore, the C terminal region of CCL28 is essential for microbial killing as an almost complete loss of antimicrobial activity is seen following the removal of the C terminal 24 amino acids. The positively charged amino acids of the C-terminus directly contributed to the antimicrobial activity of CCL28. These experiments are the first to investigate the role of primary structure on the killing activity of an antimicrobial chemokine. Using flow cytometry analysis, I found that the salt-sensitive nature of CCL28 killing activity corresponds to its binding ability. Additionally, I have shown direct evidence for in vivo interaction between commensal bacteria and endogenously expressed CCL28 in the mouse large intestine. This interaction may directly correlate to the in vivo antimicrobial activity of CCL28. Lastly, I have begun to generate a CCL28 knockout mouse model to directly address the in vivo antimicrobial activity of CCL28. Vector construction and ES cell targeting by the vector has been completed, chimeric mouse generation remains to be done. This work represents the first systematic study of antimicrobial chemokine function. This work extends our understanding of antimicrobial proteins and their role in innate immune protection of the host and provides guidance for making better alternative antimicrobials.
College and Department
Life Sciences; Microbiology and Molecular Biology
BYU ScholarsArchive Citation
Liu, Bin, "Partial Characterization of the Antimicrobial Activity of CCL28" (2012). All Theses and Dissertations. 2967.
antimicrobial, chemokine, CCL28