title: Species-specificity of the BamA component of the bacterial outer membrane protein-assembly machinery.
abstract: The BamA protein is the key component of the Bam complex, the assembly machinery for outer membrane proteins (OMP) in gram-negative bacteria. We previously demonstrated that BamA recognizes its OMP substrates in a species-specific manner in vitro. In this work, we further studied species specificity in vivo by testing the functioning of BamA homologs of the proteobacteria Neisseria meningitidis, Neisseria gonorrhoeae, Bordetella pertussis, Burkholderia mallei, and Escherichia coli in E. coli and in N. meningitidis. We found that no BamA functioned in another species than the authentic one, except for N. gonorrhoeae BamA, which fully complemented a N. meningitidis bamA mutant. E. coli BamA was not assembled into the N. meningitidis outer membrane. In contrast, the N. meningitidis BamA protein was assembled into the outer membrane of E. coli to a significant extent and also associated with BamD, an essential accessory lipoprotein of the Bam complex.Various chimeras comprising swapped N-terminal periplasmic and C-terminal membrane-embedded domains of N. meningitidis and E. coli BamA proteins were also not functional in either host, although some of them were inserted in the OM suggesting that the two domains of BamA need to be compatible in order to function. Furthermore, conformational analysis of chimeric proteins provided evidence for a 16-stranded β-barrel conformation of the membrane-embedded domain of BamA.
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Elena B
authors.initials: EB
authors.lastname: Volokhina
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Grijpstra
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Frank
authors.initials: F
authors.lastname: Beckers
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Erika
authors.initials: E
authors.lastname: Lindh
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Viviane
authors.initials: V
authors.lastname: Robert
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Tommassen
authors.affiliation: Department of Molecular Microbiology and Institute of Biomembranes, Utrecht University, Utrecht, The Netherlands.
authors.forename: Martine P
authors.initials: MP
authors.lastname: Bos
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D005816:Genetic Complementation Test; D006090:Gram-Negative Bacteria / Q000235:genetics* / Q000378:metabolism; D015151:Immunoblotting; D046912:Multiprotein Complexes / Q000235:genetics* / Q000378:metabolism*; D010957:Plasmids / Q000235:genetics; D011487:Protein Conformation; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013045:Species Specificity
chemical_list: D001425:Bacterial Outer Membrane Proteins; C503914:BamA protein, E coli; D029968:Escherichia coli Proteins; D046912:Multiprotein Complexes