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The LPS transport system D (LptD) Family [Function: Biogenesis/Secretion] Seed alignment | Full alignment | Pfam page | TC-DB page

In Gram-negative bacteria, the components of the outer membrane are synthesized in the cytoplasm or the inner membrane and must therefore traverse the inner membrane and the periplasm on the way to their final destination. Lipopolysaccharide molecules (LPS) are an essential component of the bacterial outer membrane and consist of a hydrophobic membrane anchor (lipid A) and an oligosaccharide core region that can be extended in some bacteria by a repeating oligosaccharide, the O-antigen. An outer membrane protein, which probably forms a ß-barrel, is required for the appearance of LPS at the bacterial cell surface. This protein is known as Imp (increased membrane permeability) or OstA (organic solvent tolerance) because Escherichia coli strains expressing mutant versions of this protein showed altered membrane permeability. LptD is an essential OMP that mediates the final transport of LPS to outer leaflet. LptD forms a novel 26-stranded ß-barrel, which is to our knowledge one of the largest ß-barrel reported so far. LptE adopts a roll-like structure located inside the barrel of LptD to form an unprecedented two-protein 'barrel and plug' architecture. The structure, molecular dynamics simulations and functional assays suggest that the hydrophilic O-antigen and the core oligosaccharide of the LPS may pass through the barrel and the lipid A of the LPS may be inserted into the outer leaflet of the outer membrane through a lateral opening between strands ß1 and ß26 of LptD.

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Literature references

Dynamics of an LPS translocon induced by substrate and an antimicrobial peptide
Nat Chem Biol. 2021 Feb;17(2):187-195. doi: 10.1038/s41589-020-00694-2. Epub 2020 Nov 16.
PMID: 33199913

Reversible autoinhibitory regulation of Escherichia coli metallopeptidase BepA for selective ß-barrel protein degradation
Proc Natl Acad Sci U S A. 2020 Nov 10;117(45):27989-27996. doi: 10.1073/pnas.2010301117. Epub 2020 Oct 22.
PMID: 33093205

Presence of substrate aids lateral gate separation in LptD
Biochim Biophys Acta Biomembr. 2020 Jan 1;1862(1):183025. doi: 10.1016/j.bbamem.2019.07.013. Epub 2019 Jul 25.
PMID: 31351059

Substrate binding to BamD triggers a conformational change in BamA to control membrane insertion
Proc Natl Acad Sci U S A. 2018 Mar 6;115(10):2359-2364. doi: 10.1073/pnas.1711727115. Epub 2018 Feb 20.
PMID: 29463713

A Peptidomimetic Antibiotic Interacts with the Periplasmic Domain of LptD from Pseudomonas aeruginosa
ACS Chem Biol. 2018 Mar 16;13(3):666-675. doi: 10.1021/acschembio.7b00822. Epub 2018 Jan 23.
PMID: 29359918

Distinctive Roles for Periplasmic Proteases in the Maintenance of Essential Outer Membrane Protein Assembly
J Bacteriol. 2017 Sep 19;199(20):e00418-17. doi: 10.1128/JB.00418-17. Print 2017 Oct 15.
PMID: 28784813

Protein Epitope Mimetics: From New Antibiotics to Supramolecular Synthetic Vaccines
Acc Chem Res. 2017 Jun 20;50(6):1323-1331. doi: 10.1021/acs.accounts.7b00129. Epub 2017 Jun 1.
PMID: 28570824

LptD is a promising vaccine antigen and potential immunotherapeutic target for protection against Vibrio species infection
Sci Rep. 2016 Dec 6;6:38577. doi: 10.1038/srep38577.
PMID: 27922123

Characterization of a stalled complex on the ß-barrel assembly machine
Proc Natl Acad Sci U S A. 2016 Aug 2;113(31):8717-22. doi: 10.1073/pnas.1604100113. Epub 2016 Jul 20.
PMID: 27439868

Solution Structure and Dynamics of LptE from Pseudomonas aeruginosa
Biochemistry. 2016 May 31;55(21):2936-43. doi: 10.1021/acs.biochem.6b00313. Epub 2016 May 19.
PMID: 27166502

Structural and Functional Characterization of the LPS Transporter LptDE from Gram-Negative Pathogens
Structure. 2016 Jun 7;24(6):965-976. doi: 10.1016/j.str.2016.03.026. Epub 2016 May 5.
PMID: 27161977

The composition of the global and feature specific cyanobacterial core-genomes
Front Microbiol. 2015 Mar 19;6:219. doi: 10.3389/fmicb.2015.00219. eCollection 2015.
PMID: 25852675

Accumulation of phosphatidic acid increases vancomycin resistance in Escherichia coli
J Bacteriol. 2014 Sep;196(18):3214-20. doi: 10.1128/JB.01876-14. Epub 2014 Jun 23.
PMID: 24957626

Structural basis for lipopolysaccharide insertion in the bacterial outer membrane
Nature. 2014 Jul 3;511(7507):108-11. doi: 10.1038/nature13484. Epub 2014 Jun 18.
PMID: 24990751

Structural basis for outer membrane lipopolysaccharide insertion
Nature. 2014 Jul 3;511(7507):52-6. doi: 10.1038/nature13464. Epub 2014 Jun 18.
PMID: 24990744

LptE binds to and alters the physical state of LPS to catalyze its assembly at the cell surface
Proc Natl Acad Sci U S A. 2014 Jul 1;111(26):9467-72. doi: 10.1073/pnas.1402746111. Epub 2014 Jun 17.
PMID: 24938785

Protease homolog BepA (YfgC) promotes assembly and degradation of ß-barrel membrane proteins in Escherichia coli
Proc Natl Acad Sci U S A. 2013 Sep 17;110(38):E3612-21. doi: 10.1073/pnas.1312012110. Epub 2013 Sep 3.
PMID: 24003122

Biogenesis of the Gram-negative bacterial outer membrane
Curr Opin Microbiol. 2004 Dec;7(6):610-6. doi: 10.1016/j.mib.2004.10.011.
PMID: 15556033

Identification of an outer membrane protein required for the transport of lipopolysaccharide to the bacterial cell surface
Proc Natl Acad Sci U S A. 2004 Jun 22;101(25):9417-22. doi: 10.1073/pnas.0402340101. Epub 2004 Jun 10.
PMID: 15192148

Imp/OstA is required for cell envelope biogenesis in Escherichia coli
Mol Microbiol. 2002 Sep;45(5):1289-302. doi: 10.1046/j.1365-2958.2002.03091.x.
PMID: 12207697

Proteins in this family with 3D-structure
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