Assembly of Outer Membrane β-Barrel Proteins: the Bam Complex

Malinverni, Juliana C.; Silhavy, Thomas J.

doi:10.1128/ecosalplus.4.3.8

Cited by 32 publications

(22 citation statements)

References 222 publications

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“…Grouping of genes in each pathway was determined by their associated GO terms and based on orthology with well-characterized E . coli proteins [ 21 , 62 , 63 ]. PG, peptidoglycan; BL, β-lactamases.…”

Section: Resultsmentioning

confidence: 99%

A global regulatory system links virulence and antibiotic resistance to envelope homeostasis in Acinetobacter baumannii

et al. 2018

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The nosocomial pathogen Acinetobacter baumannii is a significant threat due to its ability to cause infections refractory to a broad range of antibiotic treatments. We show here that a highly conserved sensory-transduction system, BfmRS, mediates the coordinate development of both enhanced virulence and resistance in this microorganism. Hyperactive alleles of BfmRS conferred increased protection from serum complement killing and allowed lethal systemic disease in mice. BfmRS also augmented resistance and tolerance against an expansive set of antibiotics, including dramatic protection from β-lactam toxicity. Through transcriptome profiling, we showed that BfmRS governs these phenotypes through global transcriptional regulation of a post-exponential-phase-like program of gene expression, a key feature of which is modulation of envelope biogenesis and defense pathways. BfmRS activity defended against cell-wall lesions through both β-lactamase-dependent and -independent mechanisms, with the latter being connected to control of lytic transglycosylase production and proper coordination of morphogenesis and division. In addition, hypersensitivity of bfmRS knockouts could be suppressed by unlinked mutations restoring a short, rod cell morphology, indicating that regulation of drug resistance, pathogenicity, and envelope morphogenesis are intimately linked by this central regulatory system in A. baumannii. This work demonstrates that BfmRS controls a global regulatory network coupling cellular physiology to the ability to cause invasive, drug-resistant infections.

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Section: Resultsmentioning

confidence: 99%

A global regulatory system links virulence and antibiotic resistance to envelope homeostasis in Acinetobacter baumannii

et al. 2018

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“…BamB is an outer membrane lipoprotein included in a complex that has been shown to be involved in the assembly of outer membrane β-barrel proteins in E. coli and Salmonella (Malinverni and Silhavy, 2011;Namdari et al, 2012). The deletion of bamB leads to a drastic virulence defect in mice, characterized by a low spleen infection level (Fardini et al, 2007).…”

Section: Systemic Infection Is Not Required For Long Term Intestinal mentioning

confidence: 99%

Role of systemic infection, cross contaminations and super‐shedders in Salmonella carrier state in chicken

Menanteau

Kempf

Trotereau

et al. 2018

Environmental Microbiology

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Carriage of Salmonella is often associated with a high level of bacterial excretion and generally occurs after a short systemic infection. However, we do not know whether this systemic infection is required or whether the carrier-state corresponds to continuous reinfection or real persistence in caecal tissue. The use of a Salmonella Enteritidis bamB mutant demonstrated that a carrier-state could be obtained in chicken in the absence of systemic infection. The development of a new infection model in isolator showed that a marked decrease in animal reinfection and host-to-host transmission between chicks led to a heterogeneity of S. Enteritidis excretion and colonization contrary to what was observed in cages. This heterogeneity of infection was characterized by the presence of super-shedders, which constantly disseminated Salmonella to the low-shedder chicks, mainly through airborne movements of contaminated dust particles. The presence of super-shedders, in the absence of host-to-host transmission, demonstrated that constant reinfection was not required to induce a carrier-state. Finally, our results suggest that low-shedder chicks do not have a higher capability to destroy Salmonella but instead can block initial Salmonella colonization. This new paradigm opens new avenues to improve understanding of the carrier-state mechanisms and to define new strategies to control Salmonella infections.© 2018 Society for Applied Microbiology and John Wiley & Sons Ltd.

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“…Both OMPs and lipoproteins pass through the Sec translocon after synthesis in the cytoplasm but their biogenesis pathways diverge at the periplasmic face of the IM. After signal sequence cleavage, OMPs are thought to be protected in their unfolded state by periplasmic chaperones until they are delivered to the BamABCDE complex for assembly into the OM (24). Indeed, biogenesis of LptD is dependent on both the periplasmic chaperone SurA (25) and the Bam complex (12).…”

mentioning

confidence: 99%

Lipoprotein LptE is required for the assembly of LptD by the β-barrel assembly machine in the outer membrane of Escherichia coli

Chimalakonda

Ruiz

Chng

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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113

114

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Most Gram-negative bacteria contain lipopolysaccharide (LPS), a glucosamine-based phospholipid, in the outer leaflet of the outer membrane (OM). LPS is unique to the bacterial OM and, in most cases, essential for cell viability. Transport of LPS from its site of synthesis to the cell surface requires eight essential proteins, MsbA and LptABCDEFG. Although the key players have been identified, the mechanism of LPS transport and assembly is not clear. The stable LptD/E complex is present at the OM and functions in the final stages of LPS assembly. Here, we have identified the mutant allele lptE6, which causes a two-amino-acid deletion in the lipoprotein LptE that affects its interaction with LptD. Highly specific suppressor mutations were isolated not only in lptD but also in bamA, which encodes the central component of the β-barrel assembly machine. We show that lptE6 and both suppressor mutations affect the assembly of the LptD/E complex and suggest that the lipoprotein LptE interacts with LptD while this protein is being assembled by the β-barrel assembly machine.

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Assembly of Outer Membrane β-Barrel Proteins: the Bam Complex

Cited by 32 publications

References 222 publications

A global regulatory system links virulence and antibiotic resistance to envelope homeostasis in Acinetobacter baumannii

A global regulatory system links virulence and antibiotic resistance to envelope homeostasis in Acinetobacter baumannii

Role of systemic infection, cross contaminations and super‐shedders in Salmonella carrier state in chicken

Lipoprotein LptE is required for the assembly of LptD by the β-barrel assembly machine in the outer membrane of Escherichia coli

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