Part of the outer membrane protein assembly complex (Bam), which is involved in assembly and insertion of beta-barrel proteins into the outer membrane. Constitutes, with BamD, the core component of the assembly machinery. Efficient substrate folding and insertion into the outer membrane requires all 5 subunits A lateral gate may open between the first and last strands of the BamA beta-barrel that allows substrate to insert into the outer membrane; comparison of the structures of complete and nearly complete Bam complexes show there is considerable movement of all 5 proteins ; (Microbial infection) Acts as a receptor for CdiA-EC93, the contact-dependent growth inhibition (CDI) effector of E.coli strain EC93; antibodies against extracellular epitopes decrease CDI. Its role in CDI is independent of the other Bam complex components Is not the receptor for CdiA from E.coli strain 536 / UPEC, which does not have the same mode of toxicity as CdiA from strain EC93; the decreased expression of bamA101 in some experiments decreases the level of outer membrane proteins in general Susceptibility to CdiA-EC93 is dependent on E.coli BamA; replacing BamA with the gene from S.typhimurium LT2, E.cloacae ATCC 13047 or D.dadantii 3937 renders cells resistant to CdiA-EC93. Cells with BamA from another bacteria no longer form CdiA-EC93-induced aggregates with EC93 cells. A chimera in which E.cloacae extracellular loops 6 and 7 are replaced with loops 6 and 7 from E.coli is susceptible to CdiA-EC93 and to CdiA-CT from strain 536 / UPEC

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