Abstract: The BAM（β-barrel assembly machinery）complex of gram-negative bacteria is composed of five subunits of BamA-E,and plays a key role in the transporting and correctly folding of β-barrel outer membrane proteins. The current knowledge of this complex is based on the several researches on few bacterial species such as Escherichia coli and Neisseria meninyitidis,whereas its function in other bacteria remains largely not-studied. In this study,we firstly constructed the bamA-,bamB-,and bamD-deletion mutants in Aeromonas hydrophilausing homologous recombination method. The altered outer membrane proteins among mutants and wild type control strain were detected by SDS-PAGE,and then identified by mass spectrometry. There were 7 differentiated proteins,and 5 of them were outer membrane proteins and rest 2 were proteases in the inner membrane. In addition,the expressions of several selected outer membrane proteins were validated by Western blotting. Results showed that the mutation of BAM complex of A. hydrophila not only affected their expressions,but also their transportation of outer membrane proteins. The transportation and expression of outer membrane protein varied in the different subunits of the system. These results indicate that the different subunit of BAM transport system in A. hydrophila may have specific characteristics on outer membrane protein transporting and folding.

Key words: protein transport, BAM complex, Aeromonas hydrophila, homologous recombination, mass spectrometry