Characterization of
 lptA
 and
 lptB
 , Two Essential Genes Implicated in Lipopolysaccharide Transport to the Outer Membrane of
 Escherichia coli

Sperandeo, Paola; Cescutti, R.; Villa, Riccardo; Benedetto, Cristiano Di; Candia, Daniela; Dehò, Gianni; Polissi, Alessandra

doi:10.1128/jb.01126-06

Cited by 219 publications

(262 citation statements)

References 43 publications

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“…Light microscopy also showed that all three depletion strains form filaments composed of 10-20 cells with constricted septa when grown without arabinose (data not shown). In agreement with our hypothesis that LptF and LptG are involved in LPS transport, similar phenotypes have been reported for cells where each of the lpt gene products LptABDE have been depleted (17)(18)(19).…”

Section: Identification Of Lptfg Assupporting

confidence: 77%

“…S2) revealed that in the presence of inducer, the cell envelope of the LptFG double-depletion strain appears normal, but depletion of LptFG results in defective envelopes that include extra membranous material in the periplasm. This phenotype is characteristic of cells where LPS transport has been compromised (18,19).…”

Section: Low Levels Of Lptf And/or Lptg Cause Increased Om Permeabilimentioning

confidence: 99%

“…Depletion of each of the lpt gene products LptABDE causes striking alterations in envelope structure (18,19). TEM (Fig.…”

Section: Low Levels Of Lptf And/or Lptg Cause Increased Om Permeabilimentioning

confidence: 99%

“…How phospholipids are transported to the OM is unknown. In contrast, several factors required for LPS transport to the cell surface have recently been identified and a transport model analogous to the aforementioned Lol system has emerged (16)(17)(18)(19). The IM-associated cytoplasmic ATPase LptB (for LPS transport) is thought to be the nucleotide-binding domain (NBD) component of an LPS ABC transporter (18), but its TM components are unknown.…”

mentioning

confidence: 99%

“…In contrast, several factors required for LPS transport to the cell surface have recently been identified and a transport model analogous to the aforementioned Lol system has emerged (16)(17)(18)(19). The IM-associated cytoplasmic ATPase LptB (for LPS transport) is thought to be the nucleotide-binding domain (NBD) component of an LPS ABC transporter (18), but its TM components are unknown. The bitopic IM protein LptC (formerly YrbK) is also required for LPS extraction from the IM (A. Polissi, personal communication); however, its simple topology suggests that it cannot serve as the integral TM component of an ABC transporter (20).…”

mentioning

confidence: 99%

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Identification of two inner-membrane proteins required for the transport of lipopolysaccharide to the outer membrane of Escherichia coli

Ruiz

Gronenberg

Kahne

et al. 2008

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

241

277

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The outer membrane (OM) of most Gram-negative bacteria contains lipopolysaccharide (LPS) in the outer leaflet. LPS, or endotoxin, is a molecule of important biological activities. In the host, LPS elicits a potent immune response, while in the bacterium, it plays a crucial role by establishing a barrier to limit entry of hydrophobic molecules. Before LPS is assembled at the OM, it must be synthesized at the inner membrane (IM) and transported across the aqueous periplasmic compartment. Much is known about the biosynthesis of LPS but, until recently, little was known about its transport and assembly. We applied a reductionist bioinformatic approach that takes advantage of the small size of the proteome of the Gram-negative endosymbiont Blochmannia floridanus to search for novel factors involved in OM biogenesis. This led to the discovery of two essential Escherichia coli IM proteins of unknown function, YjgP and YjgQ, which are required for the transport of LPS to the cell surface. We propose that these two proteins, which we have renamed LptF and LptG, respectively, are the missing transmembrane components of the ABC transporter that, together with LptB, functions to extract LPS from the IM en route to the OM.ABC transporter ͉ bioinformatics ͉ endosymbiont ͉ membrane biogenesis T he hallmark of Gram-negative bacteria is the presence of two extracytoplasmic membranes: the inner and outer membranes. The inner membrane (IM), which surrounds the cytoplasm, is separated from the outer membrane (OM) by an aqueous compartment known as the periplasm (1, 2). The IM is composed of phospholipids, integral transmembrane (TM) proteins that span the IM with ␣-helical TM domains, and lipoproteins (3, 4). In contrast, the OM is typically an asymmetric lipid bilayer where the inner leaflet is composed of phospholipids and the outer leaflet is composed mainly of lipopolysaccharide (LPS) (5). In addition, the OM contains lipoproteins and integral outer membrane proteins (OMPs), most of which span the OM via antiparallel ␤-sheets that fold into ␤-barrels (4, 6). Although some Gram-negative bacteria lack LPS and in others LPS is not essential (7), LPS is essential in Escherichia coli, Salmonella, and probably many other bacteria.In E. coli, the main function of the OM is to serve as a selective permeability barrier against many toxic chemicals, such as detergents and antibiotics (1). Porin proteins in the OM control permeability to hydrophilic molecules, but unlike typical phospholipid bilayers, the OM is quite impermeable to hydrophobic molecules, mainly because of LPS (1). For the OM to serve as a barrier, all OM components must be assembled properly. None of the components of the OM are synthesized in situ, so they must be transported to the OM from their site of synthesis. All OMPs and lipoproteins are made in the cytoplasm and cross the IM through the Sec translocon (3). After their signal sequence is removed, OMPs are thought to travel across the periplasm aided by chaperones that deliver them to the OM Bam complex (␤-barrel a...

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Section: Identification Of Lptfg Assupporting

confidence: 77%

Section: Low Levels Of Lptf And/or Lptg Cause Increased Om Permeabilimentioning

confidence: 99%

“…Depletion of each of the lpt gene products LptABDE causes striking alterations in envelope structure (18,19). TEM (Fig.…”

Section: Low Levels Of Lptf And/or Lptg Cause Increased Om Permeabilimentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Identification of two inner-membrane proteins required for the transport of lipopolysaccharide to the outer membrane of Escherichia coli

Ruiz

Gronenberg

Kahne

et al. 2008

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

241

277

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The transferred translocases: An old wine in a new bottle

Balaji

2021

Biotech and App Biochem

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The role of translocases was underappreciated and was not included as a separate class in the enzyme commission until August 2018. The recent research interests in proteomics of orphan enzymes, ionomics, and metallomics along with high‐throughput sequencing technologies generated overwhelming data and revamped this enzyme into a separate class. This offers a great opportunity to understand the role of new or orphan enzymes in general and specifically translocases. The enzymes belonging to translocases regulate/permeate the transfer of ions or molecules across the membranes. These enzyme entries were previously associated with other enzyme classes, which are now transferred to a new enzyme class 7 (EC 7). The entries that are reclassified are important to extend the enzyme list, and it is the need of the hour. Accordingly, there is an upgradation of entries of this class of enzymes in several databases. This review is a concise compilation of translocases with reference to the number of entries currently available in the databases. This review also focuses on function as well as dysfunction of translocases during normal and disordered states, respectively.

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Efflux transporter engineering markedly improves amorphadiene production in Escherichia coli

Zhang

Chen

Stephanopoulos

et al. 2016

Biotech & Bioengineering

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Metabolic engineering aims at altering cellular metabolism to produce valuable products at high yields and titers. Achieving high titers and productivity can be challenging if final products are largely accumulated intracellularly. A potential solution to this problem is to facilitate the export of these substances from cells by membrane transporters. Amorphadiene, the precursor of antimalarial drug artemisinin, is known to be secreted from Escherichia coli overexpressing the biosynthetic pathway. In order to assess the involvement of various endogenous efflux pumps in amorphadiene transport, the effects of single gene deletion of 16 known multidrug-resistant membrane efflux transporters were examined. The outer membrane protein TolC was found to be intimately involved in amorphadiene efflux. The overexpression of tolC together with ABC family transporters (macAB) or MFS family transporters (emrAB or emrKY) enhanced amorphadiene titer by more than threefold. In addition, the overexpression of transporters in the lipopolysaccharide transport system (msbA, lptD, lptCABFG) was found to improve amorphadiene production. As efflux transporters often have a wide range of substrate specificity, the multiple families of transporters were co-expressed and synergistic benefits were observed in amorphadiene production. This strategy of screening and then rationally engineering transporters can be used to improve the production of other valuable compounds in E. coli. Biotechnol. Bioeng. 2016;113: 1755-1763. © 2016 Wiley Periodicals, Inc.

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Characterization of lptA and lptB , Two Essential Genes Implicated in Lipopolysaccharide Transport to the Outer Membrane of Escherichia coli

Cited by 219 publications

References 43 publications

Identification of two inner-membrane proteins required for the transport of lipopolysaccharide to the outer membrane of Escherichia coli

Identification of two inner-membrane proteins required for the transport of lipopolysaccharide to the outer membrane of Escherichia coli

The transferred translocases: An old wine in a new bottle

Efflux transporter engineering markedly improves amorphadiene production in Escherichia coli

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