3PRW: Crystal Structure Of The Lipoprotein Bamb

beta-Barrel proteins are frequently found in the outer membrane of mitochondria, chloroplasts and Gram-negative bacteria. In Escherichia coli, these proteins are inserted in the outer membrane by the Bam (beta-barrel assembly machinery) complex, a multiprotein machinery formed by the beta-barrel protein BamA and the four peripheral membrane proteins BamB, BamC, BamD and BamE. The periplasmic part of BamA binds prefolded beta-barrel proteins by a beta-augmentation mechanism, thereby stabilizing the precursors prior to their membrane insertion. However, the role of the associated proteins within the Bam complex remains unknown. Here, we describe the crystal structure of BamB, a nonessential component of the Bam complex. The structure shows a typical eight-bladed beta-propeller fold. Two sequence stretches of BamB were previously identified to be important for interaction with BamA. In our structure, both motifs are located in close proximity to each other and contribute to a conserved region forming a narrow groove on the top of the propeller. Moreover, crystal contacts reveal two interaction modes of how BamB might bind unfolded beta-barrel proteins. In the crystal lattice, BamB binds to exposed beta-strands by beta-augmentation, whereas peptide stretches rich in aromatic residues can be accommodated in hydrophobic pockets located at the bottom of the propeller. Thus, BamB could simultaneously bind to BamA and prefolded beta-barrel proteins, thereby enhancing the folding and membrane insertion capability of the Bam complex.
PDB ID: 3PRWDownload
MMDB ID: 88110
PDB Deposition Date: 2010/11/30
Updated in MMDB: 2011/05
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 3PRW: monomeric; determined by author and by software (PISA)
Molecular Components in 3PRW
Label Count Molecule
Protein (1 molecule)
Lipoprotein Yfgl(Gene symbol: bamB)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB