BamA ß16C strand and periplasmic turns are critical for outer membrane protein insertion and assembly.
Biochem J
; 474(23): 3951-3961, 2017 11 21.
Article
em En
| MEDLINE
| ID: mdl-28974626
ABSTRACT
Outer membrane (OM) ß-barrel proteins play important roles in importing nutrients, exporting wastes and conducting signals in Gram-negative bacteria, mitochondria and chloroplasts. The outer membrane proteins (OMPs) are inserted and assembled into the OM by OMP85 family proteins. In Escherichia coli, the ß-barrel assembly machinery (BAM) contains four lipoproteins such as BamB, BamC, BamD and BamE, and one OMP BamA, forming a 'top hat'-like structure. Structural and functional studies of the E. coli BAM machinery have revealed that the rotation of periplasmic ring may trigger the barrel ß1C-ß6C scissor-like movement that promote the unfolded OMP insertion without using ATP. Here, we report the BamA C-terminal barrel structure of Salmonella enterica Typhimurium str. LT2 and functional assays, which reveal that the BamA's C-terminal residue Trp, the ß16C strand of the barrel and the periplasmic turns are critical for the functionality of BamA. These findings indicate that the unique ß16C strand and the periplasmic turns of BamA are important for the outer membrane insertion and assembly. The periplasmic turns might mediate the rotation of the periplasmic ring to the scissor-like movement of BamA ß1C-ß6C, triggering the OMP insertion. These results are important for understanding the OMP insertion in Gram-negative bacteria, as well as in mitochondria and chloroplasts.
Palavras-chave
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Plasmídeos
/
Salmonella typhimurium
/
Proteínas da Membrana Bacteriana Externa
/
Periplasma
/
Proteínas de Escherichia coli
/
Escherichia coli
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Biochem J
Ano de publicação:
2017
Tipo de documento:
Article
País de afiliação:
Reino Unido