B-265. Phosphoglucomutase of Yersinia pestis Is Required for Autoaggregation and Polymyxin B Resistance

S. Felek, E. S. Krukonis;
Univ. of Michigan, Ann Arbor, MI.

The importance of autoaggregation in virulence has been shown for many pathogenic microorganisms. Yersinia pestis, the causative agent of plague, autoaggregates within a few minutes of cessation of shaking when grown at 28°C. To find the autoaggregation factor in Y. pestis, we performed mariner-based transposon mutagenesis. After a series of enrichment steps, we identified three autoaggregation-defective mutants from three different pools. The transposon insertion was within the gene encoding phosphoglucomutase (pgm) in all three mutants. Deletion of pgm in Y. pestis KIM5 also resulted in loss of autoaggregation activity, and autoaggregation was complemented by addition of a plasmid expressing pgm. Pgm converts glucose-6-phosphate to glucose-1 phosphate. Glucose-1 phosphate is a precursor of UDP-glucose and UDP-glucose serves as a glucosyl donor and is used in teichoic acid, lipoteichoic acid, membrane glycolipids, capsules and exopolysaccharides. Furthermore, we tested our pgm mutant for antimicrobial peptide sensitivity. The pgm mutant displayed increased sensitivity to polymyxin B, with an MIC >1000-fold lower than that of the wild type Y. pestis strain, KIM5. Our findings indicate that the activity of Pgm results in modification of the surface of Y. pestis resulting in autoaggregation and antimicrobial peptide resistance.