Phosphoglucomutase ofYersinia pestisIs Required for Autoaggregation and Polymyxin B Resistance

Abstract

Yersinia pestis, the causative agent of plague, autoaggregates within a few minutes of cessation of shaking when grown at 28°C. To identify the autoaggregation factor of Y. pestis, we performed mariner-based transposon mutagenesis. Autoaggregation-defective mutants from three different pools were identified, each with a transposon insertion at a different position within the gene encoding phosphoglucomutase (pgmA; y1258). Targeted deletion of pgmA in Y. pestis KIM5 also resulted in loss of autoaggregation. Given the previously defined role for phosphoglucomutase in antimicrobial peptide resistance in other organisms, we tested the KIM5 ⌬pgmA mutant for antimicrobial peptide sensitivity. The ⌬pgmA mutant displayed >1,000-fold increased sensitivity to polymyxin B compared to the parental Y. pestis strain, KIM5. This sensitivity is not due to changes in lipopolysaccharide (LPS) since the LPSs from both Y. pestis KIM5 and the ⌬pgmA mutant are identical based on a comparison of their structures by mass spectrometry (MS), tandem MS, and nuclear magnetic resonance analyses. Furthermore, the ability of polymyxin B to neutralize LPS toxicity was identical for LPS purified from both KIM5 and the ⌬pgmA mutant. Our results indicate that increased polymyxin B sensitivity of the ⌬pgmA mutant is due to changes in surface structures other than LPS. Experiments with mice via the intravenous and intranasal routes did not demonstrate any virulence defect for the ⌬pgmA mutant, nor was flea colonization or blockage affected. Our findings suggest that the activity of PgmA results in modification and/or elaboration of a surface component of Y. pestis responsible for autoaggregation and polymyxin B resistance.

Roles of Chaperone/Usher Pathways of Yersinia pestis in a Murine Model of Plague and Adhesion to Host Cells

“…All bacteria behaved similarly under both growth conditions (data not shown), suggesting that none of the CU pathways is required for Y. pestis autoaggregation. As previously reported, the bacteria did not autoaggregate at 37°C, likely due to expression of the F1 antigen (28).…”

“…The lack of biofilm or autoaggregation phenotypes is consistent with the known role of the hms system as the major biofilmforming pathway of Y. pestis and the function of the pgmA gene in mediating autoaggregation (8,28,37,53). Importantly, we obtained significant phenotypes for adhesion of the KIM6ϩ usher deletion mutants to host cells.…”

“…In addition to biofilm formation, Y. pestis bacteria autoaggregate during growth in culture media at 28°C, and there is evidence that autoaggregation may correlate with the virulence of Yersinia spp. (28,43). We compared the Y. pestis usher deletion mutants and parental KIM6ϩ strain grown in HIB at 28°C for autoaggregation.…”

A Transposon Site Hybridization Screen IdentifiesgalUandwecBCas Important for Survival of Yersinia pestis in Murine Macrophages

“…We also cannot rule out the possibility that the LOS core of the galU mutant does not contain a significant change compared to wild type. Disruption of another pathway for synthesizing UDPglucose (pgmA, phosphoglucomutase) in Y. pestis did not lead to alterations in the LOS core even though the pgmA mutant had dramatically increased sensitivity to polymyxin B (13). Further analyses are necessary to understand the composition and the structure of the LOS core in the galU mutant.…”

Using Tn-seq To Identify Pigmentation-Related Genes of Porphyromonas gingivalis: Characterization of the Role of a Putative Glycosyltransferase

“…Phosphoglucomutase is involved in carbohydrate metabolism, and mutations in pgm are pleiotropic. Additionally, in Yersinia pestis, phosphoglucomutase activity modulates surface components that dramatically change polymyxin B susceptibility, a connection that could potentially result in pigmentation changes in P. gingivalis (29).…”