Table 1 Primers used in these study (5′ to 3′ sequence)   PA2939 CB-5083 cell line expression forward TTACCGGAATTCATGAGCAACAAGAACA expression reverse AACGGCAAGCTTTTACTTGATGAAGTCG KO up forward TGTAACTAGTATGGTCAGCACATGTTGCA KO up reverse GCCAGGGATGCGGCGGAATTCGAGAGGGCGAGGGCG KO down forward CGCCCTCGCCCTCTCGAATTCCGCCGCATCCCTGGC KO down reverse CTGACCTCGAGTTACTTGATGAAGTCGTGAC   Tet R cassette from pACYC184 EcoRI Tet forward GGTTATGAATTCGGTAGCTCAGAGAACCCTTCG

EcoRI Tet reverse GTGTTAGAATTCGATATGTTCTGCCAAGGGTT Xho Tet forward CCGGCTCGAGGGTAGCTCAGAGAACCTTCG Xho Tet reverse CCGGCTCGAGGATATGTTCTGCCAAGGGTT Construction of PA2939 knockout in S470 (strain APKO5) The PA2939 knockout vector (pAPKO) was constructed by interrupting the PA2939 sequence with a Tet cassette. DNA sequence starting

from approximately 500 bp upstream of the PA2939 start codon to 30 bp into PA2939 was amplified by PCR using the “”up”" primers given in Table 1, which added a SpeI site to the 5′ end of the DNA and mutated the 3′ end to contain an EcoRI site. The remainder of the PA2939 sequence was amplified with the “”down”" primers given in Table 1, which mutated the 5′ end to contain an EcoRI site and added an XhoI site to 3′ end. The Tet cassette was amplified from BAY 1895344 plasmid pACYC184 using primers given in Table 1 that added EcoRI sites to both ends. The three pieces were combined sequentially using the pDrive subcloning vector (Qiagen). The final construct was cut out of pDrive using SpeI and XhoI sites

and inserted into the MCS of pJQ200SK (GmR, SacB) to make plasmid pAPKO. PF-02341066 mw Triparental Olopatadine mating was used to introduce pAPKO into strain S470 using HB101/pAPKO as the donor strain, and MT616 as the helper strain. Successful conjugants were first selected on 1/2 PIA Tet (200 μg/ml) and Gm (20 μg/ml). Bacterial colonies that had undergone homologous recombination with the DNA containing the interruption of PA2939 were then counter-selected for resistance to Tet and sensitivity 5% sucrose and Gm. Knockout S470APKO5 was verified by PCR amplification of the interrupted PA2939 sequence, sequencing of the interrupted gene, and immunoblotting with anti-PaAP. S470APKO5 was complemented with vector pS41 or empty vector pMMB66EH by triparental mating, as described above. Complementation was verified by PCR, restriction digests of plasmid DNA, and aminopeptidase detection by immunoblot and activity. Vesicle isolation and purification Vesicles were purified from a method adapted from Horstman and Kuehn [11]. Bacteria were grown in LB broth overnight to early stationary phase. Cells were removed by pelleting (10,000 × g, 10 min). Supernatants were concentrated via a 100-kDa tangential filtration concentration unit (Pall-Gellman) to approximately 1/25th their original volume. The retentate was collected and centrifuged (6000 × g, 10 min) and then filtered through a 0.