The C-terminal domain of the Pseudomonas secretin XcpQ forms oligomeric rings with pore activity

Brok, Ronald G. P. M.; Gelder, Patrick Van; Winterhalter, Mathias; Ziese, Ulrike; Koster, Abraham J.; Cock, Hans de; Koster, Margot; Tommassen, Jan; Bitter, Wilbert

doi:10.1006/jmbi.1999.3340

Cited by 76 publications

(97 citation statements)

References 33 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Secretins are multimeric OM proteins in which a conserved C-terminal ␤-barrel rich domain is implicated in forming the multimeric OM channel (39 -42). Typically, 6 -14 identical subunits form the ringlike structure of the secretin (39,(42)(43)(44)(45)(46)(47)(48)(49)(50)(51)(52). Despite similarities in overall architecture of the secretin and Wza multimers, the respective monomers share no primary sequence similarity.…”

Section: Discussionmentioning

confidence: 99%

Translocation of Group 1 Capsular Polysaccharide in Escherichia coli Serotype K30

Nesper

Hill

Paiment

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

The late steps in assembly of capsular polysaccharides (CPS) and their translocation to the bacterial cell surface are not well understood. The Wza protein was shown previously to be required for the formation of the prototype group 1 capsule structure on the surface of Escherichia coli serotype K30 (Drummelsmith, J., and Whitfield, C. (2000) EMBO J. 19, 57-66). Wza is a conserved outer membrane lipoprotein that forms multimers adopting a ringlike structure, and collective evidence suggests a role for these structures in the export of capsular polymer across the outer membrane. Wza was purified in the native form and with a C-terminal hexahistidine tag. Wza His 6 was acylated and functional in capsule assembly, although its efficiency was slightly reduced in comparison to the native Wza protein. Ordered two-dimensional crystals of Wza His 6 were obtained after reconstitution of purified multimers into lipids. Electron microscopy of negatively stained crystals and Fourier filtering revealed ringlike multimers with an average outer diameter of 8.84 nm and an average central cavity diameter of 2.28 nm. Single particle analysis yielded projection structures at an estimated resolution of 3 nm, favoring a structure for the Wza His 6 containing eight identical subunits. A derivative of Wza (Wza*) in which the original signal sequence was replaced with that from OmpF showed that the native acylated N terminus of Wza is critical for formation of normal multimeric structures and for their competence for CPS assembly, but not for targeting Wza to the outer membrane. In the presence of Wza*, CPS accumulated in the periplasm but was not detected on the cell surface. Chemical cross-linking of intact cells suggested formation of a transmembrane complex minimally containing Wza and the inner membrane tyrosine autokinase Wzc.In Gram-negative bacteria, macromolecules destined for the cell surface or the extracellular environment must cross both the inner (IM) 1 and the outer membrane (OM). In protein export, where the processes are arguably best understood, secretion systems with varying complexity accomplish the translocation steps; all involve multi-enzyme complexes where an outer membrane protein (channel) is linked directly, or via helper proteins, to IM components.Cell-associated capsular polysaccharides (CPS) and their secreted (cell-free) counterparts, exopolysaccharides (EPS), represent another type of macromolecule that must be transported across the cell envelope. The early steps in assembly of these polymers are reasonably well established. However, there is little understanding of the terminal steps, including the mechanism by which they cross the bacterial cell envelope and the machinery involved.In Escherichia coli, more than 80 antigenically distinct capsular (K) polysaccharide structures are recognized. They are divided into four groups based on the organization of their genetic loci, polymerization mechanisms, and regulation (1). Group 1 and 2 capsules have received the most attention, and they involve biosynthet...

show abstract

Section: Discussionmentioning

confidence: 99%

Translocation of Group 1 Capsular Polysaccharide in Escherichia coli Serotype K30

Nesper

Hill

Paiment

et al. 2003

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…17,19 Secretins are large homo-oligomeric assemblies built up of 50-70 kDa subunits, with 12-14 subunits forming a ring structure of approximately 100-150 Å in diameter. 20,21,22,23,24,25,26,27,28 They comprise a superfamily 29,30 and form components of several distinct secretion systems in the outer membrane, including the type-two secretion system (TIISS), 31,32 type-three secretion system (TIIISS) 26 and Type-IV pilus biogenesis system. 30,33,34 All secretins consist of two major regions.…”

Section: (31)mentioning

confidence: 99%

“…35 It is highly conserved and predicted to contain several -strands 36 embedded in the outer membrane to form the actual pore through which transport occurs. 21 The N-terminal periplasmic region displays conservation only in secretins from related secretion pathways 29 and may be involved in substrate recognition, 28,37 gating of the proposed channel 35,38 and DNA binding 39 as well as contributing to subunit oligomerization. 35,40 The atomic structures of periplasmic fragments from two secretins, EscC from enteropathogenic E. coli and GspD from enterotoxigenic E. coli, have previously been determined.…”

Section: (31)mentioning

confidence: 99%

The Extra-Membranous Domains of the Competence Protein HofQ Show DNA Binding, Flexibility and a Shared Fold with Type I KH Domains

Tarry

Jääskeläinen

Paino

et al. 2011

Journal of Molecular Biology

View full text Add to dashboard Cite

Secretins form large oligomeric assemblies in the membrane that control both macromolecular secretion and uptake. Several Pasteurellaceae are naturally competent for transformation but the mechanism for DNA assimilation is largely unknown. In Haemophilus influenzae, the secretin ComE has been demonstrated to be essential for the DNA uptake. In closely related Aggregatibacter actinomycetemcomitans, an opportunistic pathogen in periodontitis, the ComE homolog HofQ is believed to be the outer membrane DNA translocase. Here we report the structure of the extra-membranous domains of HofQ at 2.3 Å resolution by X-ray crystallography. We also show that the extra-membranous domains of HofQ are capable of DNA binding. The structure reveals two secretin-like folds, the first of which is formed via means of a domain swap. The second domain displays extensive structural similarity to KH-domains, including the presence of a GxxG motif, which is essential for the nucleotide binding function of KH-domains, suggesting a possible mechanism for DNA binding by HofQ. The data indicate a direct involvement in DNA acquisition and provides insight into the molecular basis for natural competence.

show abstract

“…The type II secretion apparatus is composed of at least 13 different proteins and, despite their role as mediators of outer membrane translocation, several of these components are localized to the cytoplasmic membrane (16,18,19). It is believed that they interact with components in the outer membrane, including a putative gated pore to form a multiprotein secretion complex that spans the Gram-negative cell envelope (18,(20)(21)(22)(23). The number of assembled secretion complexes per bacterium is thought to be relatively low.…”

mentioning

confidence: 99%

“…The number of assembled secretion complexes per bacterium is thought to be relatively low. As few as 50-100 complexes were estimated to exist during logarithmic growth in Pseudomonas aeruginosa (22). However, it was not known whether these complexes were localized to a specific region or were uniformly distributed in the cell envelope.…”

mentioning

confidence: 99%

Directed polar secretion of protease from single cells of Vibrio cholerae via the type II secretion pathway

Scott

Dossani

Sandkvist

2001

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

View full text Add to dashboard Cite

Bacteria have long been thought of as little more than sacks of homogeneously distributed enzymes. However, recent cytological studies indicate that bacteria are compartmentalized with proteins involved in processes such as cell division, motility, chemotaxis, and development located at distinct sites. We have used the green fluorescent protein as a reporter to determine the cellular distribution of the extracellular protein secretion (eps)-encoded type II secretion complex responsible for extracellular secretion of cholera toxin and hemagglutinin͞protease in Vibrio cholerae. Real-time monitoring of green fluorescent protein fused to EpsM in living cells indicated that, like the single polar flagellum, the Eps complex is located at the old pole after cell division. Eps-dependent protease secretion was also visualized in single cells by fluorescence microscopy by using intramolecularly quenched casein. This analysis demonstrated that active protease secretion is focused at the poles and colocalizes with the site of the polar Eps apparatus. These results suggest that the type II secretion complex is responsible for directed delivery of virulence factors during cholera pathogenesis.

show abstract

The C-terminal domain of the Pseudomonas secretin XcpQ forms oligomeric rings with pore activity

Cited by 76 publications

References 33 publications

Translocation of Group 1 Capsular Polysaccharide in Escherichia coli Serotype K30

Translocation of Group 1 Capsular Polysaccharide in Escherichia coli Serotype K30

The Extra-Membranous Domains of the Competence Protein HofQ Show DNA Binding, Flexibility and a Shared Fold with Type I KH Domains

Directed polar secretion of protease from single cells of Vibrio cholerae via the type II secretion pathway

Contact Info

Product

Resources

About