Sorting of lipoproteins to the outer membrane in E. coli

Tokuda, Harukuni; Matsuyama, Shin-ichi

doi:10.1016/j.bbamcr.2004.02.005

Cited by 225 publications

(239 citation statements)

References 46 publications

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“…In Gram-negative bacteria, vesiculation models seem less likely given the structural barrier provided by the peptidoglycan exoskeleton, which is sandwiched between the two membranes [38]. Bacterial lipoproteins clearly depend on a specific transfer protein during outer membrane biogenesis, suggesting that other lipids are transported by similar mechanisms [39]. Lipocalins represent an important class of lipid transfer proteins, and Blc, while a bacterial lipoprotein anchored in the inner leaflet of the outer membrane, is a lipocalin of unknown function.…”

Section: Discussionmentioning

confidence: 99%

The membrane bound bacterial lipocalin Blc is a functional dimer with binding preference for lysophospholipids

et al. 2006

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Lipocalins, a widespread multifunctional family of small proteins (15-25 kDa) have been first described in eukaryotes and more recently in Gram-negative bacteria. Bacterial lipocalins belonging to class I are outer membrane lipoproteins, among which Blc from E. coli is the better studied. Blc is expressed under conditions of starvation and high osmolarity, conditions known to exert stress on the cell envelope. The structure of Blc that we have previously solved (V. Campanacci, D. Nurizzo, S. Spinelli, C. Valencia, M. Tegoni, C. Cambillau, FEBS Lett. 562 (2004) 183-188.) suggested its possible role in binding fatty acids or phospholipids. Both physiological and structural data on Blc, therefore, point to a role in storage or transport of lipids necessary for membrane maintenance. In order to further document this hypothesis for Blc function, we have performed binding studies using fluorescence quenching experiments. Our results indicate that dimeric Blc binds fatty acids and phospholipids in a micromolar K d range. The crystal structure of Blc with vaccenic acid, an unsaturated C18 fatty acid, reveals that the binding site spans across the Blc dimer, opposite to its membrane anchored face. An exposed unfilled pocket seemingly suited to bind a polar group attached to the fatty acid prompted us to investigate lyso-phospholipids, which were found to bind in a nanomolar K d range. We discuss these findings in terms of a potential role for Blc in the metabolism of lysophospholipids generated in the bacterial outer membrane.

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Section: Discussionmentioning

confidence: 99%

The membrane bound bacterial lipocalin Blc is a functional dimer with binding preference for lysophospholipids

et al. 2006

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“…The protein encoded by CDS PSHAb0140 (hereafter called PssA) is a 577 aa lipoprotein and the sequence analysis of its leader peptide (LipoP prediction: http://www.cbs. dtu.dk/services/LipoP; Juncker et al, 2003) predicted that it is transported to and inserted into the inner face of the outer membrane via the Lol lipoprotein sorting pathway (Tokuda & Matsuyama, 2004). Moreover, in silico analysis of the PssA amino acid sequence with the InterPro software (http://www.ebi.ac.uk/InterProScan; Zdobnov & Apweiler, 2001) predicted the presence of three tetratricopeptide repeat (TPR) domains (IPR001440), encompassing amino acid positions 40 and 160 of the protein, and of two LysM peptidoglycan-binding domains (IPR002482) at the Cterminal side.…”

Section: Construction Of 12-26 Cosmid Subclones and Testmentioning

confidence: 99%

PssA is required for α-amylase secretion in Antarctic Pseudoalteromonas haloplanktis

et al. 2010

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Extracellular protein secretion is an essential feature in bacterial physiology. The ability to efficiently secrete diverse hydrolytic enzymes represents a key nutritional strategy for all bacteria, including micro-organisms living in extreme and hostile habitats, such as cold environments. However, little is known about protein secretion mechanisms in psychrophilic bacteria. In this study, the recombinant secretion of a cold-adapted α-amylase in the Antarctic Gram-negative Pseudoalteromonas haloplanktis TAC125 was investigated. By a combination of several molecular techniques, the function of the pssA gene was related to α-amylase secretion in this psychrophilic bacterium. Deletion of the pssA gene completely abolished amylase secretion without affecting the extracellular targeting of other substrates mediated by canonical secretion systems. The pssA gene product, PssA, is a multidomain lipoprotein, predicted to be localized in the bacterial outer membrane, and displaying three TPR (tetratricopeptide repeat) domains and two LysM modules. Based on functional annotation of these domains, combined with the experimental results reported herein, we suggest a role for PssA as a molecular adaptor, in charge of recruiting other cellular components required for specific α-amylase secretion. To the best of our knowledge, no proteins exhibiting the same domain organization have previously been linked to protein secretion.

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“…These authors used an L. monocytogenes mutant defective in lipoprotein diacylglyceryl transferase (Lgt), an enzyme involved in lipoprotein processing. Three aspects of their study should be highlighted: (i) new findings concerning the roles of Lgt and lipoprotein-specific signal peptidase II (Lsp) during lipoprotein processing (22); (ii) the identification of 26 of the 68 lipoproteins predicted in the initial annotation of the L. monocytogenes strain EGD-e genome (7); and (iii) experimental evidence that a few of these lipoproteins are regulated by PrfA, the master virulence regulator of L. monocytogenes (8). Below, we discuss the significance of these findings separately.…”

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confidence: 99%

“…Upon processing, lipoproteins are ultimately tethered to the membrane via a lipid moiety, diacylglycerol, which is covalently bound to an N-terminal conserved cysteine residue. Work performed with gram-negative bacteria has indicated that the lipidation reaction, carried out by the enzyme lipoprotein diacylglyceryl transferase (Lgt), is followed by cleavage of the signal peptide (22). The enzyme responsible for the latter reaction is the lipoprotein-specific signal peptidase II (Lsp), which recognizes a genuine L Ϫ3 -S/A Ϫ2 -A/G Ϫ1 -C ϩ1 "lipobox."…”

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confidence: 99%

“…The latter modification takes place after cleavage of the signal peptide by Lsp, which leaves the amino group of the cysteine residue free. Thus, the widely accepted model establishes that enzymes involved in prelipoprotein processing act in a tightly Lgt3Lsp3Lnt order (22). Genome analyses of low-GϩC-content gram-positive bacteria, which include L. monocytogenes, have shown that an lnt gene homolog is not present.…”

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confidence: 99%

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