The Periplasmic Chaperone SurA Exploits Two Features Characteristic of Integral Outer Membrane Proteins for Selective Substrate Recognition

Hennecke, Gerrit; Nolte, Jessica; Volkmer, Rudolf; Schneider‐Mergener, Jens; Behrens, Susanne

doi:10.1074/jbc.m413742200

Cited by 99 publications

(106 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Thus, the chaperoning mechanism described here for Skp may be also be important for SurA. However, whereas SurA binding to small peptides has been described (37)(38)(39)(40), the mechanism for protecting ␤-barrels from aggregation remains unclear.…”

Section: Skp Prevents the Aggregation Of Ompa By Forming A Stable Commentioning

confidence: 87%

The cavity-chaperone Skp protects its substrate from aggregation but allows independent folding of substrate domains

Walton

Sandoval

Fowler

et al. 2009

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

113

116

View full text Add to dashboard Cite

Outer membrane proteins (OMPs) of Gram-negative bacteria are synthesized in the cytosol and must cross the periplasm before insertion into the outer membrane. The 17-kDa protein (Skp) is a periplasmic chaperone that assists the folding and insertion of many OMPs, including OmpA, a model OMP with a membrane embedded ␤-barrel domain and a periplasmic ␣␤ domain. Structurally, Skp belongs to a family of cavity-containing chaperones that bind their substrates in the cavity, protecting them from aggregation. However, some substrates, such as OmpA, exceed the capacity of the chaperone cavity, posing a mechanistic challenge. Here, we provide direct NMR evidence that, while bound to Skp, the ␤-barrel domain of OmpA is maintained in an unfolded state, whereas the periplasmic domain is folded in its native conformation. Complementary cross-linking and NMR relaxation experiments show that the OmpA ␤-barrel is bound deep within the Skp cavity, whereas the folded periplasmic domain protrudes outside of the cavity where it tumbles independently from the rest of the complex. This domain-based chaperoning mechanism allows the transport of ␤-barrels across the periplasm in an unfolded state, which may be important for efficient insertion into the outer membrane.cavity-based ͉ outer membrane M any molecular chaperones have evolved cavity-like structures to bind their non-native substrates. Classic examples, such as the chaperonins, bind the substrate in the cavity formed by their open rings and protect them from aggregation. Cycles of ATP binding and hydrolysis, coupled with substrate binding and release, then help the substrate achieve its native conformation (1). Because the cavities of these chaperones have limited capacities, binding substrates larger than the cavity requires a portion of the substrate to be bound inside the cavity while the rest of the substrate remains outside. In these cases, however, the entire substrate remains unfolded while bound to the open ring of the chaperone (2-4).The 17-kDa protein (Skp) is a periplasmic chaperone present in many Gram-negative bacteria involved in the folding and insertion of proteins in the outer membrane (5-7). The crystal structure of Skp revealed a trimer with a ''jellyfish'' architecture where a central cavity is formed by long tentacle-like helical protrusions emanating from a body domain (Fig. 1A) (8, 9). The Skp structure was unexpectedly similar to that of prefoldin, a cytosolic molecular chaperone present in archea and eukarya (8-10). Although Skp is a trimer (8, 9, 11) and prefoldin is a hexamer (12, 13), both proteins share jellyfish architectures with a central cavity ( Fig. 1 A and B). In prefoldin, this cavity has been shown to bind substrate proteins (10, 13). Prefoldin thus belongs to a family of chaperones sometimes referred to as ''holdases.'' These chaperones are ATP independent and, in contrast to chaperonins, do not directly facilitate folding of their substrates. Instead they protect the substrates from aggregation by holding them in their cavities, and subs...

show abstract

Section: Skp Prevents the Aggregation Of Ompa By Forming A Stable Commentioning

confidence: 87%

The cavity-chaperone Skp protects its substrate from aggregation but allows independent folding of substrate domains

Walton

Sandoval

Fowler

et al. 2009

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

113

116

View full text Add to dashboard Cite

show abstract

“…The proline contents of invasin, Ail, and PsaA are in the order of ϳ4%, ϳ3%, and ϳ2%, respectively. Moreover, all these three adhesins contain the SurA recognition motif (aromatic-X-aromatic, where "X" is any amino acid that is bordered before and after by any aromatic amino acid) that is a characteristic of ␤-barrel proteins (42,80,81). Hence, a role for PPIase activity in OMP assembly is realistic.…”

Section: Discussionmentioning

confidence: 99%

“…Using mass spectrometric analysis, we have previously determined that OmpA is one of the reduced OMPs that result upon surA removal in Y. pseudotuberculosis (16). Interestingly, OmpA is assumed to be a true substrate of SurA (18,42). Hence, we wanted to test this with our experimental setup by measuring the percent OM assembly efficiency of OmpA in Y. pseudotuberculosis with or without SurA.…”

Section: Sura Is Required For Proper Folding and Om Insertion Of Invamentioning

confidence: 99%

“…Hence, we wanted to test this with our experimental setup by measuring the percent OM assembly efficiency of OmpA in Y. pseudotuberculosis with or without SurA. Our analysis also included one other ␤-barrel OMP, the general porin OmpF, that is also considered a SurA substrate (18,42). Levels of OmpA and OmpF in surA mutant bacteria were determined using immunoblotting with specific rabbit-and mouse-derived antibodies, respectively.…”

Section: Sura Is Required For Proper Folding and Om Insertion Of Invamentioning

confidence: 99%

See 1 more Smart Citation

Demarcating SurA Activities Required for Outer Membrane Targeting of Yersinia pseudotuberculosis Adhesins

Obi

Francis

2013

Infect Immun

View full text Add to dashboard Cite

SurA is a periplasmic protein folding factor involved in chaperoning and trafficking of outer membrane proteins across the Gram-negative bacterial periplasm. In addition, SurA also possesses peptidyl-prolyl cis/trans isomerase activity. We have previously reported that in enteropathogenic Yersinia pseudotuberculosis, SurA is needed for bacterial virulence and envelope integrity. In this study, we investigated the role of SurA in the assembly of important Yersinia adhesins. Using genetic mutation, biochemical characterization, and an in vitro-based bacterial host cell association assay, we confirmed that surface localization of the invasin adhesin is dependent on SurA. As a surA deletion also has some impact on the levels of individual components of the BAM complex in the Yersinia outer membrane, abolished invasin surface assembly could reflect both a direct loss of SurA-dependent periplasmic targeting and a potentially compromised BAM complex assembly platform in the outer membrane. To various degrees, the assembly of two other adhesins, Ail and the pH 6 antigen fibrillum PsaA, also depends on SurA. Consequently, loss of SurA leads to a dramatic reduction in Yersinia attachment to eukaryotic host cells. Genetic complementation of surA deletion mutants indicated a prominent role for SurA chaperone function in outer membrane protein assembly. Significantly, the N terminus of SurA contributed most of this SurA chaperone function. Despite a dominant chaperoning role, it was also evident that SurA isomerization activity did make a modest contribution to this assembly process.

show abstract

“…1A) (15). The mechanism of interaction between SurA and OMPs has been the subject of many studies (16)(17)(18)(19). However, questions remain in terms of how SurA recognizes and binds to nascent OMPs.…”

mentioning

confidence: 99%

Insights into the Function and Structural Flexibility of the Periplasmic Molecular Chaperone SurA

Zhong

Ferrell

et al. 2012

Journal of Bacteriology

View full text Add to dashboard Cite

SurA is the primary periplasmic molecular chaperone that facilitates the folding and assembling of outer membrane proteins (OMPs) in Gram-negative bacteria. Deletion of the surA gene in Escherichia coli leads to a decrease in outer membrane density and an increase in bacterial drug susceptibility. Here, we conducted mutational studies on SurA to identify residues that are critical for function. One mutant, SurA V37G , significantly reduced the activity of SurA. Further characterization indicated that SurA V37G was structurally similar to, but less stable than, the wild-type protein. The loss of activity in SurA V37G could be restored through the introduction of a pair of Cys residues and the subsequent formation of a disulfide bond. Inspired by this success, we created three additional SurA constructs, each containing a disulfide bond at different regions of the protein between two rigid secondary structural elements. The formation of disulfide bond in these mutants has no observable detrimental effect on protein activity, indicating that SurA does not undergo large-scale conformational change while performing its function.

show abstract

The Periplasmic Chaperone SurA Exploits Two Features Characteristic of Integral Outer Membrane Proteins for Selective Substrate Recognition

Cited by 99 publications

References 30 publications

The cavity-chaperone Skp protects its substrate from aggregation but allows independent folding of substrate domains

The cavity-chaperone Skp protects its substrate from aggregation but allows independent folding of substrate domains

Demarcating SurA Activities Required for Outer Membrane Targeting of Yersinia pseudotuberculosis Adhesins

Insights into the Function and Structural Flexibility of the Periplasmic Molecular Chaperone SurA

Contact Info

Product

Resources

About