Translocation path of a substrate protein through its Omp85 transporter

Baud, C.; Guérin, Jean-Dominique; Petit, Emmanuelle; Lesne, E.; Dupré, Elian; Locht, Camille; Jacob‐Dubuisson, Françoise

doi:10.1038/ncomms6271

Cited by 46 publications

(57 citation statements)

References 45 publications

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“…The new structure of FhaC (PDB code 4QKY) now shows loop 6 in the same conformation as observed for BamA and TamA, with the conserved (V/I)RG(F/Y) motif interacting with the opposite wall of the β-barrel domain (Figure 3C). These new structural insights align well with recent biophysical and crosslinking studies for FhaC and BamA which have both shown that a conformational change in loop 6 is not required for function [26,32,33]. While the new FhaC structure helps solidify the idea that loop 6 and the (V/I)RG(F/Y) do not cycle between two differing conformations as first thought, exactly what role this highly conserved motif serves remains elusive.…”

Section: A Shared Conformation For Loop 6 Among the Omp85 Superfamilysupporting

confidence: 72%

“…In addition, the other extracellular loops in FhaC have an open conformation; the structure of FhaC is well suited to mediate secretion given the less restricted passage through the β-barrel domain to the surface once the H1 helix in the pore has been ejected. (Figure 3A) [30,32,33]. However, BamA and TamA both differ significantly in that loop 6 is able to fully cap their β-barrel domain, sealing the membrane and occluding a direct path from the periplasm to the outside of the cell (Figures 2A and 3A) [22,25].…”

Section: Lateral Opening In Bamamentioning

confidence: 99%

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The β-barrel membrane protein insertase machinery from Gram-negative bacteria

Noinaj

Rollauer

Buchanan

2015

Current Opinion in Structural Biology

103

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The outer membranes (OM) of Gram-negative bacteria contain a host of β-barrel outer membrane proteins (OMPs) which serve many functions for cell survival and virulence. The biogenesis of these OMPs is mediated by the β-barrel assembly machinery (BAM) complex which is composed of five components including the essential core component called BamA that mediates the insertase function within the OM. The crystal structure of BamA has recently been reported from three different species, including a full-length structure from Neisseria gonorrhoeae. Mutagenesis and functional studies identified several conformational changes within BamA that are required for function, providing a significant advancement towards unraveling exactly how BamA and the BAM complex are able to fold and insert new OMPs in the OM.

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Section: A Shared Conformation For Loop 6 Among the Omp85 Superfamilysupporting

confidence: 72%

Section: Lateral Opening In Bamamentioning

confidence: 99%

The β-barrel membrane protein insertase machinery from Gram-negative bacteria

Noinaj

Rollauer

Buchanan

2015

Current Opinion in Structural Biology

103

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“…In addition, we found that the pore-forming domain also influences this specificity. In particular, the chimeric protein containing the periplasmic domain of HMW1B and the pore-forming domain of EtpB was associated with only low-level secretion of the HMW1 propiece and only low-level HMW1-mediated adherence, emphasizing that not all TpsB pore-forming domains are the same, consistent with recent observations by Baud et al (41).…”

supporting

confidence: 80%

Structural Determinants of the Interaction between the TpsA and TpsB Proteins in the Haemophilus influenzae HMW1 Two-Partner Secretion System

2015

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The two-partner secretion (TPS) pathway in Gram-negative bacteria consists of a TpsA exoprotein and a cognate TpsB outer membrane pore-forming translocator protein. Previous work has demonstrated that the TpsA protein contains an N-terminal TPS domain that plays an important role in targeting the TpsB protein and is required for secretion. The nontypeable Haemophilus influenzae HMW1 and HMW2 adhesins are homologous proteins that are prototype TpsA proteins and are secreted by the HMW1B and HMW2B TpsB proteins. In the present study, we sought to define the structural determinants of HMW1 interaction with HMW1B during the transport process and while anchored to the bacterial surface. Modeling of HMW1B revealed an N-terminal periplasmic region that contains two polypeptide transport-associated (POTRA) domains and a C-terminal membrane-localized region that forms a pore. Biochemical studies demonstrated that HMW1 engages HMW1B via interaction between the HMW1 TPS domain and the HMW1B periplasmic region, specifically, the predicted POTRA1 and POTRA2 domains. Subsequently, HMW1 is shuttled to the HMW1B pore, facilitated by the N-terminal region, the middle region, and the NPNG motif in the HMW1 TPS domain. Additional analysis revealed that the interaction between HMW1 and HMW1B is highly specific and is dependent upon the POTRA domains and the pore-forming domain of HMW1B. Further studies established that tethering of HMW1 to the surface-exposed region of HMW1B is dependent upon the external loops of HMW1B formed by residues 267 to 283 and residues 324 to 330. These observations may have broad relevance to proteins secreted by the TPS pathway. IMPORTANCESecretion of HMW1 involves a recognition event between the extended form of the HMW1 propiece and the HMW1B POTRA domains. Our results identify specific interactions between the HMW1 propiece and the periplasmic HMW1B POTRA domains. The results also suggest that the process of HMW1 translocation involves at least two discrete steps, including initial interaction between the HMW1 propiece and the HMW1B POTRA domains and then a separate translocation event. We have also discovered that the HMW1B pore itself appears to influence the translocation process. These observations extend our knowledge of the two-partner secretion system and may be broadly relevant to other proteins secreted by the TPS pathway. G ram-negative bacteria have developed a number of pathways for targeting proteins to an extracellular location (1). Among the most common of these pathways is the two-partner secretion (TPS) system. TPS systems typically consist of a large secreted protein called a TpsA protein (encoded by a tpsA gene) and a cognate outer membrane pore-forming translocator protein called a TpsB protein (encoded by a tpsB gene) (2). In addition, some TPS systems include a protein that has glycosyltransferase activity and modifies the TpsA protein (3).TpsA proteins are rich in ␤ structure and are involved in a variety of functions on the bacterial surface or in the extracellular mil...

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“…As indicated by its name, TPS systems are characterized by two proteins, generically known as TpsB (CdiB) and TpsA (CdiA), that are secreted across the Gram-negative envelope. TpsB partners are outer-membrane proteins of the Omp85 family, and export TpsA exoprotein cargos through the central lumen of their β-barrels 21 . In many instances, the TpsA partner is thought to remain tethered non-covalently to TpsB, thereby projecting the exoprotein outward from the surface of the secreting bacterium (Fig.…”

Section: The Discovery Of Contact-dependent Growth Inhibition (Cdi)mentioning

confidence: 99%

“…The N-terminal region also contains the TPS transport domain (also known as the hemagglutinin activation domain, PF05860), which is required for export across the outer membrane. CdiB recognizes the TPS transport domain as it emerges into the periplasm and transports CdiA through the central pore in its β-barrel domain 21; 32; 33 . CdiA proteins also share FHA-1 (PF05594) and FHA-2 (PF13332) peptide repeats with FHA/FhaB (Fig.…”

Section: Architecture Of Cdia Effector Proteinsmentioning

confidence: 99%

Contact-Dependent Growth Inhibition (CDI) and CdiB/CdiA Two-Partner Secretion Proteins

Willett

Ruhe

Goulding

et al. 2015

Journal of Molecular Biology

108

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Bacteria have developed several strategies to communicate and compete with one another in complex environments. One important mechanism of inter-bacterial competition is contact-dependent growth inhibition (CDI), in which some Gram-negative bacteria use CdiB/CdiA two-partner secretion proteins to suppress the growth of neighboring target cells. CdiB is an Omp85 outer-membrane protein that exports and assembles CdiA exoproteins onto the inhibitor-cell surface. CdiA binds to receptors on susceptible bacteria and subsequently delivers its C-terminal toxin domain (CdiA-CT) into the target cell. CDI systems also encode CdiI immunity proteins, which specifically bind to the CdiA-CT and neutralize its toxin activity, thereby protecting CDI+ cells from auto-inhibition. Remarkably, CdiA-CT sequences are highly variable between bacteria, as are the corresponding CdiI immunity proteins. Variations in CDI toxin/immunity proteins suggest that these systems function in bacterial self/nonself recognition and thereby play an important role in microbial communities. In this review, we discuss recent advances in the biochemistry, structural biology and physiology of CDI.

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Translocation path of a substrate protein through its Omp85 transporter

Cited by 46 publications

References 45 publications

The β-barrel membrane protein insertase machinery from Gram-negative bacteria

The β-barrel membrane protein insertase machinery from Gram-negative bacteria

Structural Determinants of the Interaction between the TpsA and TpsB Proteins in the Haemophilus influenzae HMW1 Two-Partner Secretion System

Contact-Dependent Growth Inhibition (CDI) and CdiB/CdiA Two-Partner Secretion Proteins

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