One basic hypothesis states that either the PPIase activity or some chaperone activity of Mip and Mip-like proteins might be involved in the maturation and trafficking of proteins derived from pathogens. It goes on to add that these activities may also allow Mip and

Mip-like proteins to recognize host receptors and inhibit the host’s defense response. Despite studies performed in numerous laboratories, none of Mip’s substrates or molecular targets has yet been discovered. Xcc, a Gram-negative Gammaproteobacterium, is the causal agent of black rot disease in cruciferous crops worldwide (Hayward, 1993). Our own recent studies have shown that a mip-like gene (here called mipXcc) exists within Xcc and encodes a protein, MipXcc, which exhibits a PPIase activity specifically inhibited by FK-506 OSI-744 order (Zang et al., 2007). Mutagenesis analysis revealed that Xcc requires a functional MipXcc for full virulence and proliferation in host plants. Further study showed that, in mutants lacking a working mipXcc, Xcc was unable to produce its usual amounts of exopolysaccharide and its extracellular proteases were significantly less active (Zang et al., 2007). Although the mechanism by which MipXcc affects the activity of extracellular proteases remains unclear, we have made an effort to address

this issue. In this study, we provide evidence that Osimertinib in vivo MipXcc interacts with the major Xcc protease PrtA and assists its maturation in the periplasm. The bacterial strains and plasmids used in this project are listed

in Table 1. The primers used are listed in Table 2. Escherichia coli strains JM109 and M15 (Qiagen, Germany) were grown in LB medium at 37 °C. The bacterial two-hybrid Arachidonate 15-lipoxygenase reporter strain (here named BTHrst) (Stratagene, La Jolla, CA) was grown in M9 His-dropout medium at 30 °C. Xcc strains were grown in NYG medium at 28 °C. Antibiotics were used at the following final concentrations: rifampicin, 50 μg mL−1; kanamycin, 25 μg mL−1; ampicillin, 100 μg mL−1; chloramphenicol, 34 μg mL−1; gentamicin, 10 μg mL−1; streptomycin, 12.5 μg mL−1; and tetracycline, 15 μg mL−1 for E. coli and 5 μg mL−1 for Xcc. Standard DNA manipulation was performed as described by Sambrook & Russell (2001). The conjugation of Xcc to E. coli was performed as described by Turner et al. (1985). Restriction enzymes and DNA ligase were purchased from Promega (Madison, WI) and used in accordance with the manufacturer’s instructions. All clones were confirmed by sequencing. Fragment of prtA was PCR-amplified and cloned into pLAFR3. The resulting plasmid pR3PrtA was introduced into the mipXcc mutant NK2699 and the prtA mutant 001F10 by triparental conjugation. Fragment of mipXcc was conjugated at the 3′ end with 6xHis coding sequences, then PCR-amplified and cloned into pLAFR3. The derived plasmid pR3MipH6 was introduced into NK2699.