Assembly of Integral Membrane Proteins from the Periplasm into the Outer Membrane

Kleinschmidt, Jörg H.

doi:10.1128/9781555815806.ch3

Cited by 2 publications

(2 citation statements)

References 216 publications

(314 reference statements)

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“…In Gram-negative bacteria, molecular chaperones facilitate the transport of outer membrane proteins across the periplasm (for reviews, see, for example, refs and ). The Skp trimer forms stable 1:1 complexes with several unfolded OMPs with nanomolar affinity. , Skp facilitates folding of OmpA into lipid bilayers containing negatively charged phosphatidylglycerol (PG) but inhibits folding into lipid bilayers composed of zwitterionic PC or PE .…”

Section: Resultsmentioning

confidence: 99%

“…Periplasmic chaperones for OMPs (see ref for a review), like the 17 kDa protein (Skp), , were discovered and characterized by genetic and microbiological studies. Skp from E. coli was shown to facilitate folding of OmpA from E. coli into lipid bilayers in the presence of negatively charged lipids or lipopolysaccharide. , Genetic studies also showed that the assembly of OMPs of bacteria, mitochondria, and chloroplasts into outer membranes requires the barrel assembly machinery (BAM) complex .…”

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confidence: 99%

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The Lipid Bilayer-Inserted Membrane Protein BamA of Escherichia coli Facilitates Insertion and Folding of Outer Membrane Protein A from Its Complex with Skp

Patel

Kleinschmidt

2013

Biochemistry

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Folding of β-barrel membrane proteins, either from a urea-unfolded form or from chaperone-bound aqueous forms, has been characterized for pure lipid bilayers. The impact of preinserted integral proteins from biomembranes has not been examined in biophysical comparisons, but this knowledge is important for the characterization of protein assembly machinery in membranes to distinguish specific effects from unspecific effects. Here, folding was studied for a β-barrel membrane protein, outer membrane protein A (OmpA) from Escherichia coli, in the absence and presence of two other preinserted integral proteins, BamA of the β-barrel assembly machinery complex (BAM) from E. coli and FomA from Fusobacterium nucleatum. Three different preformed lipid membranes of phosphatidylcholine were prepared to compare the folding kinetics of OmpA, namely, proteoliposomes containing either BamA or FomA and pure liposomes. Urea-unfolded OmpA folded faster into phosphatidylcholine bilayers containing FomA than into pure lipid bilayers, but the kinetics of OmpA folding and insertion were fastest for bilayers containing BamA. Incorporation of BamA into lipid bilayers composed of phosphatidylcholine and phosphatidylethanolamine greatly weakened the inhibiting effect of phosphatidylethanolamine on the folding of OmpA. Folding of OmpA from its complex with the periplasmic chaperone Skp into bilayers composed of phosphatidylethanolamine and phosphatidylcholine was inhibited in the absence of BamA but facilitated when BamA was present, indicating an interaction of Skp-OmpA complexes with BamA.

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

The Lipid Bilayer-Inserted Membrane Protein BamA of Escherichia coli Facilitates Insertion and Folding of Outer Membrane Protein A from Its Complex with Skp

Patel

Kleinschmidt

2013

Biochemistry

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Analysis of the periplasmic proteome of Pseudomonas aeruginosa, a metabolically versatile opportunistic pathogen

et al. 2009

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The Gram-negative bacterium Pseudomonas aeruginosa is a main cause of infection in hospitalized, burned, immunocompromised, and cystic fibrosis patients. Many processes essential for P. aeruginosa pathogenesis, e.g., nutrient uptake, antibiotic resistance, and virulence, take place in the cell envelope and depend on components residing in the periplasmic space. Recent high-throughput studies focused on P. aeruginosa membrane compartments. However, the composition and dynamics of its periplasm remain largely uncharacterized. Here, we report a detailed description of the periplasmic proteome of the wild-type P. aeruginosa strain PAO1 by 2-DE and MALDI-TOF/TOF analysis. Three extraction methods were compared at proteome level in order to achieve the most reliable and comprehensive periplasmic protein map. A total of 495 spots representing 395 different proteins were identified. Most of the high intensity spots corresponded to periplasmic proteins, while cytoplasmic contaminants were mainly detected among faint spots. The majority of the identified periplasmic proteins is involved in transport, cell-envelope integrity, and protein folding control. Notably, more than 30% still has an unpredicted function. This work provides the first overview of the P. aeruginosa periplasm and offers the basis for future studies on periplasmic proteome changes occurring during P. aeruginosa adaptation to different environments and/or antibiotic treatments.

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Assembly of Integral Membrane Proteins from the Periplasm into the Outer Membrane

Cited by 2 publications

References 216 publications

The Lipid Bilayer-Inserted Membrane Protein BamA of Escherichia coli Facilitates Insertion and Folding of Outer Membrane Protein A from Its Complex with Skp

The Lipid Bilayer-Inserted Membrane Protein BamA of Escherichia coli Facilitates Insertion and Folding of Outer Membrane Protein A from Its Complex with Skp

Analysis of the periplasmic proteome of Pseudomonas aeruginosa, a metabolically versatile opportunistic pathogen

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