(A) Predicted open reading frames in the pPAU1 circular plasmid sequenced from Pa ATCC43949 presented in a linear diagram. Most of the open reading frames on the plasmid predict transposases with high similarity to those found in Y. pestis (see Table 1) (B) Two-dimensional SDS-PAGE gel of Pa supernatants grown at 30°C (left panel) and 37°C (right panel). Proteins that are differentially expressed are circled and labelled S1-S12. Analysis of proteins S1-S12 by tryptic digest and comparison to a database of predicted tryptic digest fragments from predicted Pa proteins identified S1 as YP1042-like and S4 as Ail-like. The fully annotated sequence of pPAU1 is GenBank accession number AC FM162592.