Architectures of Lipid Transport Systems for the Bacterial Outer Membrane

Ekiert, Damian; Bhabha, Gira; Isom, Georgia L.; Greenan, Garrett; Овчинников, С. Г.; Henderson, Ian R.; Cox, Jeffery S.; Vale, Ronald D.

doi:10.1016/j.cell.2017.03.019

Cited by 205 publications

(373 citation statements)

References 64 publications

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“…The OmpC‐Mla system is important for the maintenance of OM lipid asymmetry, and is proposed to do so via retrograde PL transport (Malinverni and Silhavy, ; Chong et al ., ). Two other related systems, the Pqi and Yeb systems, have recently been suggested to be involved in PL transport (Ekiert et al ., ); however, cells lacking either or both of these systems do not exhibit obvious OM defects unless the OmpC‐Mla system is also removed (Nakayama and Zhang‐Akiyama, ). To determine if the OmpC‐Mla system plays a major role in retrograde PL transport in cells lacking the Tol‐Pal complex, we examined OM PG/CL turnover in Δ tolA cells also lacking MlaC, the putative periplasmic lipid chaperone of the system.…”

Section: Resultsmentioning

confidence: 99%

Outer membrane lipid homeostasis via retrograde phospholipid transport in Escherichia coli

Shrivastava

Jiang

Chng

2017

Molecular Microbiology

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Biogenesis of the outer membrane (OM) in Gram-negative bacteria, which is essential for viability, requires the coordinated transport and assembly of proteins and lipids, including lipopolysaccharides (LPS) and phospholipids (PLs), into the membrane. While pathways for LPS and OM protein assembly are well-studied, how PLs are transported to and from the OM is not clear. Mechanisms that ensure OM stability and homeostasis are also unknown. The trans-envelope Tol-Pal complex, whose physiological role has remained elusive, is important for OM stability. Here, we establish that the Tol-Pal complex is required for PL transport and OM lipid homeostasis in Escherichia coli. Cells lacking the complex exhibit defects in lipid asymmetry and accumulate excess PLs in the OM. This imbalance in OM lipids is due to defective retrograde PL transport in the absence of a functional Tol-Pal complex. Thus, cells ensure the assembly of a stable OM by maintaining an excess flux of PLs to the OM only to return the surplus to the inner membrane. Our findings also provide insights into the mechanism by which the Tol-Pal complex may promote OM invagination during cell division.

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Section: Resultsmentioning

confidence: 99%

Outer membrane lipid homeostasis via retrograde phospholipid transport in Escherichia coli

Shrivastava

Jiang

Chng

2017

Molecular Microbiology

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“…These five groups are (i) the lol pathway for lipoprotein transport, (ii) six lipoproteins, (iii) multidrug efflux pumps, (iv) the baeRS two component‐system and (v) the mla pathway for phospholipid transport. All of these are involved in cell envelope maintenance (Raffa and Raivio, ; Malinverni and Silhavy, ; Lin et al ., ; Yoon et al ., ; Ekiert et al ., ; Grabowicz and Silhavy, ).…”

Section: Impacts Of Los‐deficiency On a Baumannii Physiologymentioning

confidence: 98%

Expanding the paradigm for the outer membrane: Acinetobacter baumannii in the absence of endotoxin

Powers

Trent

2017

Molecular Microbiology

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SummaryAsymmetry in the outer membrane has long defined the cell envelope of Gram-negative bacteria. This asymmetry, with lipopolysaccharide (LPS) or lipooligosaccharide (LOS) exclusively in the outer leaflet of the membrane, establishes an impermeable barrier that protects the cell from a number of stressors in the environment. Work done over the past 5 years has shown that Acinetobacter baumannii has the remarkable capability to survive with inactivated production of lipid A biosynthesis and the absence of LOS in its outer membrane. The implications of LOS-deficient A. baumannii are far-reaching -from impacts on cell envelope biogenesis and maintenance, bacterial physiology, antibiotic resistance and virulence. This review examines recent work that has contributed to our understanding of LOS-deficiency and compares it to studies done on Neisseria meningitidis and Moraxella catarrhalis; the two other organisms with this capability.

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“…Low‐resolution EM data were utilized to predict oligomer structures for three targets, T0996, H1021, and H1022. For T0996, Escherichia coli YebT protein, a 25 Å resolution EM map (Electron Microscopy Data Bank [EMDB]: EMD‐8611) revealed by literature search was used to predict the homo‐hexamer structures, as shown in Figure . T0996 consists of seven homo‐hexameric rings having similar sequences.…”

Section: Resultsmentioning

confidence: 99%

Prediction of protein oligomer structures using GALAXY in CASP13

et al. 2019

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Many proteins need to form oligomers to be functional, so oligomer structures provide important clues to biological roles of proteins. Prediction of oligomer structures therefore can be a useful tool in the absence of experimentally resolved structures. In this article, we describe the server and human methods that we used to predict oligomer structures in the CASP13 experiment. Performances of the methods on the 42 CASP13 oligomer targets consisting of 30 homo‐oligomers and 12 hetero‐oligomers are discussed. Our server method, Seok‐assembly, generated models with interface contact similarity measure greater than 0.2 as model 1 for 11 homo‐oligomer targets when proper templates existed in the database. Model refinement methods such as loop modeling and molecular dynamics (MD)‐based overall refinement failed to improve model qualities when target proteins have domains not covered by templates or when chains have very small interfaces. In human predictions, additional experimental data such as low‐resolution electron microscopy (EM) map were utilized. EM data could assist oligomer structure prediction by providing a global shape of the complex structure.

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Architectures of Lipid Transport Systems for the Bacterial Outer Membrane

Cited by 205 publications

References 64 publications

Outer membrane lipid homeostasis via retrograde phospholipid transport in Escherichia coli

Outer membrane lipid homeostasis via retrograde phospholipid transport in Escherichia coli

Expanding the paradigm for the outer membrane: Acinetobacter baumannii in the absence of endotoxin

Prediction of protein oligomer structures using GALAXY in CASP13

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