FIG 7.

Mep72 binds to T3S factors and prevents proteolytic processing. (A) Western blot analysis of ExoS and PcrV secreted from 1-day-old PAO1 and mep72 mutant biofilms. The ExoS-containing sample was concentrated culture supernatant (SN). The PcrV-containing samples are from culture supernatant (SN) and cell-free biofilm matrix (BM), as indicated. Note the clear difference in size of PcrV between the wild-type and mep72 mutant in both sample types. (B) Western blot analysis of pulldown between Mep72 and T3S factors ExoS and PcrV. Planktonic PAO1 culture supernatants (PAO1 supernatant) were passed through an amylose column with or without prebound MBP-Mep72 and eluted in 10 mM maltose. Lane 1, eluate from column precharged with MBP-Mep72 after adding 10 mM maltose; lane 2, eluate from control column after adding 10 mM maltose.