The β-Barrel Assembly Machinery Complex

Leyton, Denisse L.; Belousoff, Matthew J.; Lithgow, Trevor

doi:10.1007/978-1-4939-2871-2_1

Cited by 11 publications

(6 citation statements)

References 85 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In mutant B5b, this was accompanied by the aforementioned rmd mutation, which affected CPA metabolism. BamA, together with the lipoproteins BamB, BamC, BamD, and BamE, constitutes the BAM complex that ensures the integration and folding of proteins in the outer membrane via a mechanism requiring a lateral gate and exit pore formation (31)(32)(33)(34). Pfl01_1109 includes four POTRA domains (polypeptide transport associated; Pfam PF07244) and a characteristic conserved VRGF motif in the ␤-barrel (35).…”

Section: Resultsmentioning

confidence: 99%

Hitting with a BAM: Selective Killing by Lectin-Like Bacteriocins

Ghequire

Swings

Michiels

et al. 2018

mBio

View full text Add to dashboard Cite

Lectin-like bacteriocins (LlpAs) are secreted by proteobacteria and selectively kill strains of their own or related species, and they are composed of two B-lectin domains with divergent sequences. In spp., initial binding of these antibacterial proteins to cells is mediated by the carboxy-terminal domain through d-rhamnose residues present in the common polysaccharide antigen of their lipopolysaccharide, whereas the amino-terminal domain accounts for strain selectivity of killing. Here, we show that spontaneous LlpA-resistant mutants carry mutations in one of three surface-exposed moieties of the essential β-barrel outer membrane protein insertase BamA, the core component of the BAM complex. Polymorphism of this loop in different groups is linked to LlpA susceptibility, and targeted cells all share the same signature motif in this loop. Since heterologous expression of such a gene confers LlpA susceptibility upon a resistant strain, BamA represents the primary bacteriocin selectivity determinant in pseudomonads. Contrary to modular bacteriocins that require uptake via the Tol or Ton system, parasitism of BamA as an LlpA receptor advocates a novel bacteriocin killing mechanism initiated by impairment of the BAM machinery. Bacteria secrete a variety of molecules to eliminate microbial rivals. Bacteriocins are a pivotal group of peptides and proteins that assist in this fight, specifically killing related bacteria. In Gram-negative bacteria, these antibacterial proteins often comprise distinct domains for initial binding to a target cell's surface and subsequent killing via enzymatic or pore-forming activity. Here, we show that lectin-like bacteriocins, a family of bacteriocins that lack the prototypical modular toxin architecture, also stand out by parasitizing BamA, the core component of the outer membrane protein assembly machinery. A particular surface-exposed loop of BamA, critical for its function, serves as a key discriminant for cellular recognition, and polymorphisms in this loop determine whether a strain is susceptible or immune to a particular bacteriocin. These findings suggest a novel mechanism of contact-dependent killing that does not require cellular uptake. The evolutionary advantage of piracy of an essential cellular compound is highlighted by the observation that contact-dependent growth inhibition, a distinct antagonistic system, can equally take advantage of this receptor.

show abstract

Section: Resultsmentioning

confidence: 99%

Hitting with a BAM: Selective Killing by Lectin-Like Bacteriocins

Ghequire

Swings

Michiels

et al. 2018

mBio

View full text Add to dashboard Cite

show abstract

“…The folding of the nascent OMP polypeptide is widely accepted to be a multistep process (63–65). Physico-chemical properties of the lipid (66), chaperone-dependent factors (67), and the energetic contribution of the protein primary sequence (6, 68) together play an important role in OMP assembly.…”

Section: Discussionmentioning

confidence: 99%

Energetics of side-chain partitioning of β-signal residues in unassisted folding of a transmembrane β-barrel protein

Iyer

Zadafiya

Vetal

et al. 2017

Journal of Biological Chemistry

101

View full text Add to dashboard Cite

The free energy of water-to-interface amino acid partitioning is a major contributing factor in membrane protein folding and stability. The interface residues at the C terminus of transmembrane β-barrels form the β-signal motif required for assisted β-barrel assembly in vivo but are believed to be less important for β-barrel assembly in vitro. Here, we experimentally measured the thermodynamic contribution of all 20 amino acids at the β-signal motif to the unassisted folding of the model β-barrel protein PagP. We obtained the partitioning free energy for all 20 amino acids at the lipid-facing interface (ΔΔG0w,i(φ)) and the protein-facing interface (ΔΔG0w,i(π)) residues and found that hydrophobic amino acids are most favorably transferred to the lipid-facing interface, whereas charged and polar groups display the highest partitioning energy. Furthermore, the change in non-polar surface area correlated directly with the partitioning free energy for the lipid-facing residue and inversely with the protein-facing residue. We also demonstrate that the interface residues of the β-signal motif are vital for in vitro barrel assembly, because they exhibit a side chain–specific energetic contribution determined by the change in nonpolar accessible surface. We further establish that folding cooperativity and hydrophobic collapse are balanced at the membrane interface for optimal stability of the PagP β-barrel scaffold. We conclude that the PagP C-terminal β-signal motif influences the folding cooperativity and stability of the folded β-barrel and that the thermodynamic contributions of the lipid- and protein-facing residues in the transmembrane protein β-signal motif depend on the nature of the amino acid side chain.

show abstract

“…Other outer membrane proteins (OMPs) Besides ATs and IATs, several additional monomeric OMPs can act as SCFs in DEC, namely, OmpA, Hra (Heat-resistant agglutinin), and Iha (Iron-regulated protein A homologue adhesin). OMPs are integrated to the OM via the β-barrel assembly machinery (Bam) complex (Leyton, Belousoff and Lithgow 2015;Botos, Noinaj and Buchanan 2017;Schiffrin, Brockwell and Radford 2017).…”

Section: Autotransporter Adhesins (Atas)mentioning

confidence: 99%

Molecular determinants of surface colonisation in diarrhoeagenicEscherichia coli(DEC): from bacterial adhesion to biofilm formation

Ageorges

Monteiro

Léroy

et al. 2020

FEMS Microbiology Reviews

View full text Add to dashboard Cite

Escherichia coli is primarily known as a commensal colonising the gastrointestinal tract of infants very early in life but some strains being responsible for diarrhoea, which can be especially severe in young children. Intestinal pathogenic E. coli include six pathotypes of diarrhoeagenic E. coli (DEC), namely, the (i) enterotoxigenic E. coli, (ii) enteroaggregative E. coli, (iii) enteropathogenic E. coli, (iv) enterohemorragic E. coli, (v) enteroinvasive E. coli and (vi) diffusely adherent E. coli. Prior to human infection, DEC can be found in natural environments, animal reservoirs, food processing environments and contaminated food matrices. From an ecophysiological point of view, DEC thus deal with very different biotopes and biocoenoses all along the food chain. In this context, this review focuses on the wide range of surface molecular determinants acting as surface colonisation factors (SCFs) in DEC. In the first instance, SCFs can be broadly discriminated into (i) extracellular polysaccharides, (ii) extracellular DNA and (iii) surface proteins. Surface proteins constitute the most diverse group of SCFs broadly discriminated into (i) monomeric SCFs, such as autotransporter (AT) adhesins, inverted ATs, heat-resistant agglutinins or some moonlighting proteins, (ii) oligomeric SCFs, namely, the trimeric ATs and (iii) supramolecular SCFs, including flagella and numerous pili, e.g. the injectisome, type 4 pili, curli chaperone-usher pili or conjugative pili. This review also details the gene regulatory network of these numerous SCFs at the various stages as it occurs from pre-transcriptional to post-translocational levels, which remains to be fully elucidated in many cases.

show abstract

The β-Barrel Assembly Machinery Complex

Cited by 11 publications

References 85 publications

Hitting with a BAM: Selective Killing by Lectin-Like Bacteriocins

Hitting with a BAM: Selective Killing by Lectin-Like Bacteriocins

Energetics of side-chain partitioning of β-signal residues in unassisted folding of a transmembrane β-barrel protein

Molecular determinants of surface colonisation in diarrhoeagenicEscherichia coli(DEC): from bacterial adhesion to biofilm formation

Contact Info

Product

Resources

About