β-Barrel Membrane Protein Assembly by the Bam Complex

Hagan, Christine L.; Silhavy, Thomas J.; Kahne, Daniel

doi:10.1146/annurev-biochem-061408-144611

Cited by 294 publications

(323 citation statements)

References 122 publications

Supporting

Mentioning

313

Contrasting

Unclassified

Order By: Relevance

“…These functional residues are almost all located on the top face of the protein and cluster along the central pore of the protein. In the surface representation of BamB, the localization of functional residues is indicated together with the secondary structure assignment of the first WD40 repeat (encircled numbers [1][2][3][4]. B, superposition of BamB with the Skp-Fbw7-CyclinEdegN complex (PDB code 2OVR), which was cocrystallized with an N-terminal N-degron peptide (PEP, marked in dark blue with the residual C-␣ position indicated by yellow dots).…”

Section: Resultsmentioning

confidence: 99%

“…In particular, the arrangement of the TPR [1][2][3] fold is typical for several representatives of this protein family. Notably, the TPR 1-3 fold is reminiscent, e.g., of the Hop protein, which is an adaptor protein of the Hsp chaperones in higher eukaryotic cells (PDB code 1ELR) (49) and which was crystallized with the C-terminal peptide of Hsp90.…”

Section: Resultsmentioning

confidence: 99%

“…The outer membrane architecture is highly asymmetric and composed by integral outer membrane ␤-barrel proteins, lipoproteins, lipopolysaccharides, and phospholipids (1). These components are entirely synthesized in the cytoplasm, translocated over the inner membrane, and finally delivered through the periplasm to the outer membrane by specific shuttle factors that transport their cargo to membrane receptor complexes (1,2). In Escherichia coli, lipoproteins are targeted to the OM through the LolABCDE complex system via a series of membrane and periplasmic transfer steps (3,4).…”

mentioning

confidence: 99%

See 2 more Smart Citations

Structural Basis of Outer Membrane Protein Biogenesis in Bacteria

Albrecht

Zeth

2011

Journal of Biological Chemistry

104

View full text Add to dashboard Cite

In Escherichia coli, a multicomponent BAM (␤-barrel assembly machinery) complex is responsible for recognition and assembly of outer membrane ␤-barrel proteins. The functionality of BAM in protein biogenesis is mainly orchestrated through the presence of two essential components, BamA and BamD. Here, we present crystal structures of four lipoproteins (BamB-E). Monomeric BamB and BamD proteins display scaffold architectures typically implied in transient protein interactions. BamB is a ␤-propeller protein comprising eight WD40 repeats. BamD shows an elongated fold on the basis of five tetratricopeptide repeats, three of which form the scaffold for protein recognition. The rod-shaped BamC protein has evolved through the gene duplication of two conserved domains known to mediate protein interactions in structurally related complexes. By contrast, the dimeric BamE is formed through a domain swap and indicates fold similarity to the ␤-lactamase inhibitor protein family, possibly integrating cell wall stability in BAM function. Structural and biochemical data show evidence for the specific recognition of amphipathic sequences through the tetratricopeptide repeat architecture of BamD. Collectively, our data advance the understanding of the BAM complex and highlight the functional importance of BamD in amphipathic outer membrane ␤-barrel protein motif recognition and protein delivery.Gram-negative bacteria are surrounded by two membranes, an inner membrane and the protective outer membrane (OM) 2 layer. The outer membrane architecture is highly asymmetric and composed by integral outer membrane ␤-barrel proteins, lipoproteins, lipopolysaccharides, and phospholipids (1). These components are entirely synthesized in the cytoplasm, translocated over the inner membrane, and finally delivered through the periplasm to the outer membrane by specific shuttle factors that transport their cargo to membrane receptor complexes (1, 2). In Escherichia coli, lipoproteins are targeted to the OM through the LolABCDE complex system via a series of membrane and periplasmic transfer steps (3, 4). Integral OMPs are translocated by the secretion (Sec) machinery and stabilized against premature precipitation or mislocalization in the periplasm by the three major chaperones PpiD, Skp, and SurA (4 -7). These chaperones presumably act sequentially with PpiD at an early stage, early after the OMP release into the periplasm (5). This initial rescue event is followed by Skp and SurA chaperoning at a later stage (8). Various experimental studies describing OMP folding through SurA show the particular importance of this chaperone. Phage display combined with peptide binding studies indicated SurA interactions with amphipathic OMP peptides (9, 10). Furthermore, the importance of SurA in vivo is underlined by the observation that E. coli cells being deleted in surA exhibit reduced levels of folded OmpA, OmpC, OmpF, and LamB porins (11).After the unfolded outer membrane protein is delivered through the periplasmic space, the final steps are the tetherin...

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Structural Basis of Outer Membrane Protein Biogenesis in Bacteria

Albrecht

Zeth

2011

Journal of Biological Chemistry

104

View full text Add to dashboard Cite

show abstract

“…All CU pathway components in Gram-negative bacteria are initially translocated through the inner membrane (IM) via the Sec machinery [8]. type 1 and P pili, respectively-is embedded into the OM via the β-barrel assembly machinery (BAM complex) [9,10]. The periplasmic chaperones FimC and PapD promote subunit/pilin folding as they are released by the Sec translocon and target pilus subunits to their respective usher [11,12].…”

Section: Pilus Morphology Function and Subunits (A) Morphologymentioning

confidence: 99%

Molecular mechanism of bacterial type 1 and P pili assembly

Büsch

Phan

Waksman

2015

Phil. Trans. R. Soc. A.

View full text Add to dashboard Cite

The formation of adhesive surface structures called pili or fimbriae (‘bacterial hair’) is an important contributor towards bacterial pathogenicity and persistence. To fight often chronic or recurrent bacterial infections such as urinary tract infections, it is necessary to understand the molecular mechanism of the nanomachines assembling such pili. Here, we focus on the so far best-known pilus assembly machinery: the chaperone–usher pathway producing the type 1 and P pili, and highlight the most recently acquired structural knowledge. First, we describe the subunits' structure and the molecular role of the periplasmic chaperone. Second, we focus on the outer-membrane usher structure and the catalytic mechanism of usher-mediated pilus biogenesis. Finally, we describe how the detailed understanding of the chaperone–usher pathway at a molecular level has paved the way for the design of a new generation of bacterial inhibitors called ‘pilicides’.

show abstract

“…More recent work indicates that the Bam proteins and possibly TAM (translocation assembly module) proteins participate in this process (21)(22)(23). Even though the translocated pas-senger domain of some autotransporter proteins is cleaved off (17,24), a defining characteristic of the type V protein secretion system (T5SS), a number of them remain surface associated by noncovalent bonds (25).…”

mentioning

confidence: 99%