Characterizing the dynamic nature of the Yersinia pestis periplasmic proteome in response to nutrient exhaustion and temperature change.

The periplasmic proteome of Yersinia pestis strain KIM6+ was characterized using differential 2-DE display of proteins isolated from several subcellular fractions. Circa 160 proteins were designated as periplasmic, including 62 (putative) solute-binding proteins of ATP-binding cassette (ABC) transporters (SBPs) and 46 (putative) metabolic enzymes. More than 30 SBPs were significantly increased in abundance during stationary phase cell growth, compared to the exponential phase. The data suggest that nutrient exhaustion in the stationary phase triggers cellular responses resulting in the induced expression of numerous ABC transporters, which are responsible for the import of solutes/nutrients. Limited availability of inorganic phosphate (P(i)) also caused dramatic proteomic changes. Nine proteins were functionally linked to the mobilization and import of three small molecules (P(i), phosphonate and glycerol-3-phosphate) and accounted for nearly half of the total protein mass in the periplasm of P(i)-starved cells. When cells were grown at 26 degrees C versus 37 degrees C, corresponding to ambient temperatures in the flea vector and mammalian hosts, respectively, several periplasmic proteins with no known roles in the Y. pestis life cycle were strongly altered in abundance. This included a putative nitrate/sulfonate/bicarbonate-specific SBP (Y1004), encoded by the virulence-associated plasmid pMT1 and increased in abundance at 37 degrees C.