Loss of the Lipopolysaccharide Core Biosynthesis rfaD Gene Increases Antimicrobial Chemokine Binding and Bacterial Susceptibility to CCL28 and Polymyxin: A Model for Understanding the Interface of Antimicrobial Chemokines and Bacterial Host Defense Avoidance Mechanisms
In order to better understand the mechanism of antimicrobial chemokine activity, including binding to and killing of bacteria, random transposon mutagenesis was performed in Yersinia pseudotuberculosis. Resulting mutants were screened for increased binding to chemokine and high binding clones were selected for further study. One mutant, designated mutant 27, was found to have a single insertion mutation in the rfaD gene. The rfaD gene product is involved in heptose biosynthesis, one of the sugars of the inner core oligosaccharide of Gram- negative lipopolysaccharide (LPS). Mutant 27 was found to bind both CCL25 and CCL28, two antimicrobial chemokines, more efficiently than the wild type bacteria. This clone was also found to be more susceptible to CCL28- mediated killing and polymyxin activity. Complementation with a plasmid bearing the full rfaDFC operon restored the wild type phenotype in both regards. These data suggest that normal LPS expression by Y. pseudotuberculosis serves to protect the bacteria from the antimicrobial function of chemokines and other antimicrobial proteins of the mammalian innate immune system.
College and Department
Life Sciences; Microbiology and Molecular Biology
BYU ScholarsArchive Citation
Lew, Cynthia S., "Loss of the Lipopolysaccharide Core Biosynthesis rfaD Gene Increases Antimicrobial Chemokine Binding and Bacterial Susceptibility to CCL28 and Polymyxin: A Model for Understanding the Interface of Antimicrobial Chemokines and Bacterial Host Defense Avoidance Mechanisms" (2012). Theses and Dissertations. 3756.
antimicrobial chemokines, Y. pseudotuberculosis, rfaD