The Sec system

Driessen, Arnold J.M.; Fekkes, Peter; Wolk, J.P.W. van der

doi:10.1016/s1369-5274(98)80014-3

Cited by 159 publications

(116 citation statements)

References 48 publications

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“…The general secretory pathway (Sec) has long been thought to be the only means by which proteins could traverse the cytoplasmic membrane (1). Toxins are further exported by the extracellular protein (Xcp) secretion apparatus (2) and are frequently scrutinized for their role in host-pathogen interactions (3).…”

mentioning

confidence: 99%

“…Toxins are further exported by the extracellular protein (Xcp) secretion apparatus (2) and are frequently scrutinized for their role in host-pathogen interactions (3). Sec-secreted proteins have an N-terminal sequence (i.e., secretion signal), which includes a positively charged N terminus, a hydrophobic core, and a peptidase cleavage site (e.g., Ala-X-Ala) (1).…”

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confidence: 99%

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Effects of the twin-arginine translocase on secretion of virulence factors, stress response, and pathogenesis

Ochsner

Snyder

Vasil

et al. 2002

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

189

226

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A novel secretion pathway originally found in plants has recently been discovered in bacteria and termed TAT, for ''twin-arginine translocation,'' with respect to the presence of an Arg-Arg motif in the signal sequence of TAT-secreted products. However, it is unknown whether the TAT system contributes in any way to virulence through the secretion of factors associated with pathogenesis or stress response. We found that the opportunistic pathogen Pseudomonas aeruginosa produces several virulence factors that depend on the TAT system for proper export to the periplasm, outer membrane, or extracellular milieu. We identified at least 18 TAT substrates of P. aeruginosa and characterized the pleiotropic phenotypes of a tatC deletion mutant. The TAT system proved essential for the export of phospholipases, proteins involved in pyoverdine-mediated ironuptake, anaerobic respiration, osmotic stress defense, motility, and biofilm formation. Because all these traits have been associated with virulence, we studied the role of TAT in a rat lung model. A tatC mutant did not cause the typical multifocal pulmonary abscesses and did not evoke a heavy inflammatory host response compared with wild type, indicating that tatC mutant cells are attenuated for virulence. Because the TAT apparatus is well conserved among important bacterial pathogens yet absent in mammalian cells, it represents a potential target for novel antimicrobial compounds.

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confidence: 99%

mentioning

confidence: 99%

Effects of the twin-arginine translocase on secretion of virulence factors, stress response, and pathogenesis

Ochsner

Snyder

Vasil

et al. 2002

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

189

226

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“…These preproteins are normally transferred across the cytoplasmic membrane in an extended conformation. The translocation channel or Sec machinery is a well studied heterooligomeric complex consisting of at least three integral membrane proteins, SecY, SecE, and SecG, and the peripherally bound cytoplasmic ATPase SecA (2,3).…”

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confidence: 99%

Target-directed proteolysis at the ribosome

Henrichs

Mikhaleva²,

Conz³

et al. 2005

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

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Target directed proteolysis allows specific processing of proteins in vivo. This method uses tobacco etch virus (TEV) NIa protease that recognizes a seven-residue consensus sequence. Because of its specificity, proteins engineered to contain a cleavage site are proteolysed, whereas other proteins remain unaffected. Therefore, this approach can be used to study the structure and function of target proteins in their natural environment within living cells. One application is the conditional inactivation of essential proteins, which is based on the concept that a target containing a recognition site can be inactivated by coexpressed TEV protease. We have previously identified one site in the secretion factor SecA that tolerated a TEV protease site insert. Coexpression of TEV protease in the cytoplasm led to incomplete cleavage and a mild secretion defect. To improve the efficiency of proteolysis, TEV protease was attached to the ribosome. We show here that cleaving SecA under these conditions is one way of increasing the efficiency of target directed proteolysis. The implications of recruiting novel biological activities to ribosomes are discussed. membrane protein insertion ͉ ribosome attachment ͉ transport P rotein translocation across the cytoplasmic membrane is a highly conserved process. Common features include the recognition of targeting signals of the secretory protein by dedicated cellular factors on the cis side of a membrane, a heterooligomeric channel that gates across and into the membrane, a peripherally associated component providing energy and a folding system on the trans side of the membrane (for review, see ref. 1). In bacteria, classical secretory proteins are synthesized with a N-terminal signal peptide. These preproteins are normally transferred across the cytoplasmic membrane in an extended conformation. The translocation channel or Sec machinery is a well studied heterooligomeric complex consisting of at least three integral membrane proteins, SecY, SecE, and SecG, and the peripherally bound cytoplasmic ATPase SecA (2, 3).The posttranslational targeting pathway of soluble proteins is well understood. In the cytoplasm, cleavable signal sequences are recognized by the chaperone SecB and the essential SecA protein. SecA is a multifunctional component that acts as a targeting factor, provides energy for translocation through its ATPase activity, and acts as a chaperone excluding nonsecretory proteins from translocation (4-6). Targeting of cytoplasmic membrane proteins depends on transmembrane segments that function as internal and noncleavable signal and stop-transfer sequences. Therefore, transmembrane segments do not only function in targeting but are also involved in determining the transmembrane topology (7-10). Recent evidence suggests that targeting of integral membrane proteins is cotranslational, involving the components of the signal recognition particle (SRP) system. This targeting includes the SRP itself, composed of the Ffh protein and the 4.5S RNA, and the SRP receptor FtsY (reviewe...

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“…[1][2][3]. The essential subunits of the translocase are the dissociable peripheral ATPase termed SecA and integral membrane proteins SecY and SecE (4,5).…”

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confidence: 99%

Non-bilayer Lipids Stimulate the Activity of the Reconstituted Bacterial Protein Translocase

Does

Swaving

Klompenburg

et al. 2000

Journal of Biological Chemistry

115

100

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To determine the phospholipid requirement of the preprotein translocase in vitro, the Escherichia coli SecYEG complex was purified in a delipidated form using the detergent dodecyl maltoside. SecYEG was reconstituted into liposomes composed of defined synthetic phospholipids, and proteoliposomes were analyzed for their preprotein translocation and SecA translocation ATPase activity. The activity strictly required the presence of anionic phospholipids, whereas the non-bilayer lipid phosphatidylethanolamine was found stimulatory. The latter effect could also be induced by dioleoylglycerol, a lipid that adopts a non-bilayer conformation. Phosphatidylethanolamine derivatives that prefer the bilayer state were unable to stimulate translocation. In the absence of SecG, activity was reduced, but the phospholipid requirement was unaltered. Remarkably, nonbilayer lipids were found essential for the activity of the Bacillus subtilis SecYEG complex. Optimal activity required a mixture of anionic and non-bilayer lipids at concentrations that correspond to concentrations found in the natural membrane.

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The Sec system

Cited by 159 publications

References 48 publications

Effects of the twin-arginine translocase on secretion of virulence factors, stress response, and pathogenesis

Effects of the twin-arginine translocase on secretion of virulence factors, stress response, and pathogenesis

Target-directed proteolysis at the ribosome

Non-bilayer Lipids Stimulate the Activity of the Reconstituted Bacterial Protein Translocase

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