Type V Secretion Systems in Bacteria

Autotransport in Gram-negative bacteria denotes the ability of surface-localized proteins to cross the outer membrane (OM) autonomously. Autotransporters perform this task with the help of a β-barrel transmembrane domain localized in the OM. Different classes of autotransporters have been investigated in detail in recent years; classical monomeric but also trimeric autotransporters comprise many important bacterial virulence factors. So do the two-partner secretion systems, which are a special case as the transported protein resides on a different polypeptide chain than the transporter. Despite the great interest in these proteins, the exact mechanism of the transport process remains elusive. Moreover, different periplasmic and OM factors have been identified that play a role in the translocation, making the term ‘autotransport’ debatable. In this review, we compile the wealth of details known on the mechanism of single autotransporters from different classes and organisms, and put them into a bigger perspective. We also discuss recently discovered or rediscovered classes of autotransporters.

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Identification of Autotransporter Proteins Secreted by Type V Secretion Systems in Gram-Negative Bacteria

Protein Targeting Protocols - Methods in Molecular Biology™ ◽

10.1007/1-59745-466-4_3 ◽

2007 ◽

pp. 33-46

Author(s):

Yihfen T. Yen ◽

Christos Stathopoulos

Keyword(s):

Gram Negative Bacteria ◽

Secretion Systems ◽

Gram Negative ◽

Type V Secretion ◽

Type V

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Identification of Autotransporter Proteins Secreted by Type V Secretion Systems in Gram-Negative Bacteria

Protein Targeting Protocols, Second Edition ◽

10.1385/1-59745-466-4:33 ◽

2007 ◽

pp. 33-46

Author(s):

Yihfen T. Yen ◽

Christos Stathopoulos

Keyword(s):

Gram Negative Bacteria ◽

Secretion Systems ◽

Gram Negative ◽

Type V Secretion ◽

Type V

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Type V Secretion Systems: An Overview of Passenger Domain Functions

Frontiers in Microbiology ◽

10.3389/fmicb.2019.01163 ◽

2019 ◽

Vol 10 ◽

Cited By ~ 16

Author(s):

Ina Meuskens ◽

Athanasios Saragliadis ◽

Jack C. Leo ◽

Dirk Linke

Keyword(s):

Secretion Systems ◽

Passenger Domain ◽

Type V Secretion ◽

Type V

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Structural comparison of the transport units of type V secretion systems

Biological Chemistry ◽

10.1515/hsz-2013-0162 ◽

2013 ◽

Vol 394 (11) ◽

pp. 1385-1398 ◽

Cited By ~ 8

Author(s):

Iris Gawarzewski ◽

Sander H.J. Smits ◽

Lutz Schmitt ◽

Joachim Jose

Keyword(s):

Outer Membrane ◽

Crystal Structure Analysis ◽

Type I ◽

Gram Negative Bacteria ◽

Secretion Systems ◽

X Ray ◽

Outer Membranes ◽

One Step ◽

Type V Secretion ◽

Type V

Abstract Pathogenic gram-negative bacteria have evolved several secretion mechanisms to translocate adhesins, enzymes, toxins, and other virulence factors across the inner and outer membranes. Currently, eight different secretion systems, type I–type VIII (T1SS–T8SS) plus the chaperone-usher (CU) pathway, have been identified, which act in one-step or two-step mechanisms to traverse both membrane barriers. The type V secretion system (T5SS) is dependent first on the Sec translocon within the inner membrane. The periplasmic intermediates are then secreted through aqueous pores formed by β-barrels in the outer membrane. Until now, transport across the outer membrane has not been understood on a molecular level. With respect to special characteristics revealed by crystal structure analysis, bioinformatic and biochemical data, five subgroups of T5SS were defined. Here, we compare the transport moieties of members of four subgroups based on X-ray crystal structures. For the fifth subgroup, which was identified only recently, no structures have thus far been reported. We also discuss different models for the translocation process across the outer membrane with respect to recent findings.

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An approach to chimeric subunit immunogen provides efficient protection against toxicity, type III and type v secretion systems of Shigella

International Immunopharmacology ◽

10.1016/j.intimp.2021.108132 ◽

2021 ◽

Vol 100 ◽

pp. 108132

Author(s):

Alireza Felegary ◽

Shahram Nazarian ◽

Emad Kordbacheh ◽

Javad Fathi ◽

Mohamad Ebrahim Minae

Keyword(s):

Secretion Systems ◽

Type Iii ◽

Efficient Protection ◽

Type V Secretion ◽

Type V

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Recent advances in the understanding of trimeric autotransporter adhesins

Medical Microbiology and Immunology ◽

10.1007/s00430-019-00652-3 ◽

2019 ◽

Vol 209 (3) ◽

pp. 233-242 ◽

Cited By ~ 2

Author(s):

Andreas R. Kiessling ◽

Anchal Malik ◽

Adrian Goldman

Keyword(s):

Immune System ◽

Infection Type ◽

A Priori ◽

Protein A ◽

Initial Step ◽

Infection Process ◽

Secretion Systems ◽

Specific Domain ◽

Recent Advances ◽

Type V

AbstractAdhesion is the initial step in the infection process of gram-negative bacteria. It is usually followed by the formation of biofilms that serve as a hub for further spread of the infection. Type V secretion systems engage in this process by binding to components of the extracellular matrix, which is the first step in the infection process. At the same time they provide protection from the immune system by either binding components of the innate immune system or by establishing a physical layer against aggressors. Trimeric autotransporter adhesins (TAAs) are of particular interest in this family of proteins as they possess a unique structural composition which arises from constraints during translocation. The sequence of individual domains can vary dramatically while the overall structure can be very similar to one another. This patchwork approach allows researchers to draw conclusions of the underlying function of a specific domain in a structure-based approach which underscores the importance of solving structures of yet uncharacterized TAAs and their individual domains to estimate the full extent of functions of the protein a priori. Here, we describe recent advances in understanding the translocation process of TAAs and give an overview of structural motifs that are unique to this class of proteins. The role of BpaC in the infection process of Burkholderia pseudomallei is highlighted as an exceptional example of a TAA being at the centre of infection initiation.

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Bioinformatic and Molecular Analysis of Inverse Autotransporters from Escherichia coli

mSphere ◽

10.1128/msphere.00572-19 ◽

2019 ◽

Vol 4 (4) ◽

Cited By ~ 3

Author(s):

Kelvin G. K. Goh ◽

Danilo G. Moriel ◽

Steven J. Hancock ◽

Minh-Duy Phan ◽

Mark A. Schembri

Keyword(s):

Escherichia Coli ◽

Cell Surface ◽

Biofilm Formation ◽

Secretion System ◽

Content Type ◽

E Coli ◽

Wide Range ◽

Type V Secretion ◽

K 12 ◽

Type V

ABSTRACT Proteins secreted by the type V secretion system possess multiple functions, including the capacity to mediate adhesion, aggregation, and biolfilm formation. The type V secretion system can be divided into five subclasses, one of which is the type Ve system. Proteins of the type Ve secretion system are also referred to as inverse autotransporters (IATs). In this study, we performed an in silico analysis of 126 completely sequenced Escherichia coli genomes available in the NCBI database and identified several distinct IAT-encoding gene families whose distribution varied throughout the E. coli phylogeny. The genes included three characterized IATs (intimin, fdeC, and yeeJ) and four uncharacterized IATs (here named iatA, iatB, iatC, and iatD). The four iat genes were cloned from the completely sequenced environmental E. coli strain SMS-3-5 and characterized. Three of these IAT proteins (IatB, IatC, and IatD) were expressed at the cell surface and possessed the capacity to mediate biofilm formation in a recombinant E. coli K-12 strain. Further analysis of the iatB gene, which showed a unique association with extraintestinal E. coli strains, suggested that its regulation is controlled by the LeuO global regulator. Overall, this study provides new data describing the prevalence, sequence variation, domain structure, function, and regulation of IATs found in E. coli. IMPORTANCE Escherichia coli is one of the most prevalent facultative anaerobes of the human gut. E. coli normally exists as a harmless commensal but can also cause disease following the acquisition of genes that enhance its pathogenicity. Adhesion is an important first step in colonization of the host and is mediated by an array of cell surface components. In E. coli, these include a family of adhesins secreted by the type V secretion system. Here, we identified and characterized new proteins from an emerging subclass of the type V secretion system known as the inverse autotransporters (IATs). We found that IAT-encoding genes are present in a wide range of strains and showed that three novel IATs were localized on the E. coli cell surface and mediated biofilm formation. Overall, this study provides new insight into the prevalence, function, and regulation of IATs in E. coli.

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