scholarly journals Glycine acylation and trafficking of a new class of bacterial lipoprotein by a composite secretion system

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Christopher Icke ◽  
Freya J Hodges ◽  
Karthik Pullela ◽  
Samantha A McKeand ◽  
Jack Alfred Bryant ◽  
...  
Keyword(s):  
Composite System ◽  
Cysteine Residue ◽  
Secretion System ◽  
Type I ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Cellular Functions ◽  
New Class ◽  
Domains Of Life ◽  
Protein Acylation

Protein acylation is critical for many cellular functions across all domains of life. In bacteria, lipoproteins have important roles in virulence and are targets for the development of antimicrobials and vaccines. Bacterial lipoproteins are secreted from the cytosol via the Sec pathway and acylated on an N-terminal cysteine residue through the action of three enzymes. In Gram-negative bacteria, the Lol pathway transports lipoproteins to the outer membrane. Here we demonstrate that the Aat secretion system is a composite system sharing similarity with elements of a type I secretion systems and the Lol pathway. During secretion, the AatD subunit acylates the substrate CexE on a highly conserved N-terminal glycine residue. Mutations disrupting glycine acylation interfere with membrane incorporation and trafficking. Our data reveal CexE as the first member of a new class of glycine-acylated lipoprotein, while Aat represents a new secretion system that displays the substrate lipoprotein on the cell surface.

scholarly journals Glycine acylation and trafficking of a new class of bacterial lipoprotein by a composite secretion system

2020 ◽  
Author(s):  
Christopher Icke ◽  
Freya J. Hodges ◽  
Karthik Puella ◽  
Samantha A. McKeand ◽  
Jack A. Bryant ◽  
...  
Keyword(s):  
Composite System ◽  
Cysteine Residue ◽  
Secretion System ◽  
Type I ◽  
Secretion Systems ◽  
Cellular Functions ◽  
E Coli ◽  
New Class ◽  
Secretion Pathway ◽  
Bacterial Lipoprotein

AbstractProtein acylation is critical for many cellular functions including signal transduction, cell division and development. In bacteria, such lipoproteins have important roles in virulence and are therefore potential targets for the development of novel antimicrobials and vaccines. To date, all known bacterial lipoproteins are secreted from the cytosol via the Sec pathway, acylated on an N-terminal cysteine residue through the action of Lgt, Lsp and Lnt, and then targeted to the appropriate cellular location. In the case of Gram-negative bacteria, the lipoprotein trafficking Lol pathway transports the lipoproteins to the outer membrane where most substrate molecules are retained within the cell. Here we identify a new secretion pathway that displays the substrate lipoprotein on the cell surface. We demonstrate that the previously identified E. coli Aat secretion system is a composite system that shares similarity with type I secretion systems and elements of the Lol pathway. Remarkably, during secretion by the Aat system, the AatD subunit acylates the substrate CexE on a highly conserved N-terminal glycine residue (rather than the canonical cysteine). Mutations in AatD or CexE that disrupt glycine acylation interfere with membrane incorporation and trafficking. Our data suggest that CexE is the first member of a new class of glycine-acylated bacterial lipoprotein, while Aat represents a new secretion system that we propose be defined as a lipoprotein secretion system (LSS).

scholarly journals Folding Control in the Path of Type 5 Secretion

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 341
Author(s):  
Nathalie Dautin
Keyword(s):  
Protein Folding ◽  
Virulence Factors ◽  
Secretion System ◽  
Gram Negative Bacteria ◽  
Secretion Systems ◽  
Gram Negative ◽  
Final Destination ◽  
Cell Compartments ◽  
Recent Addition ◽  
Functionally Diverse

The type 5 secretion system (T5SS) is one of the more widespread secretion systems in Gram-negative bacteria. Proteins secreted by the T5SS are functionally diverse (toxins, adhesins, enzymes) and include numerous virulence factors. Mechanistically, the T5SS has long been considered the simplest of secretion systems, due to the paucity of proteins required for its functioning. Still, despite more than two decades of study, the exact process by which T5SS substrates attain their final destination and correct conformation is not totally deciphered. Moreover, the recent addition of new sub-families to the T5SS raises additional questions about this secretion mechanism. Central to the understanding of type 5 secretion is the question of protein folding, which needs to be carefully controlled in each of the bacterial cell compartments these proteins cross. Here, the biogenesis of proteins secreted by the Type 5 secretion system is discussed, with a focus on the various factors preventing or promoting protein folding during biogenesis.

scholarly journals An A/U-Rich Enhancer Region Is Required for High-Level Protein Secretion through the HlyA Type I Secretion System

2017 ◽  
Vol 84 (1) ◽  
Author(s):  
Sakshi Khosa ◽  
Romy Scholz ◽  
Christian Schwarz ◽  
Mirko Trilling ◽  
Hartmut Hengel ◽  
...  
Keyword(s):  
Ribosomal Protein ◽  
Protein Secretion ◽  
Fusion Proteins ◽  
Untranslated Region ◽  
Secretion System ◽  
Type I ◽  
Secretion Systems ◽  
Enhancer Region ◽  
Ribosomal Protein S1 ◽  
Cellular Expression

ABSTRACTEfficient protein secretion is often a valuable alternative to classic cellular expression to obtain homogenous protein samples. Early on, bacterial type I secretion systems (T1SS) were employed to allow heterologous secretion of fusion proteins. However, this approach was not fully exploited, as many proteins could not be secreted at all or only at low levels. Here, we present an engineered microbial secretion system which allows the effective production of proteins up to a molecular mass of 88 kDa. This system is based on the hemolysin A (HlyA) T1SS of the Gram-negative bacteriumEscherichia coli, which exports polypeptides when fused to a hemolysin secretion signal. We identified an A/U-rich enhancer region upstream ofhlyArequired for effective expression and secretion of selected heterologous proteins irrespective of their prokaryotic, viral, or eukaryotic origin. We further demonstrate that the ribosomal protein S1 binds to thehlyAA/U-rich enhancer region and that this region is involved in the high yields of secretion of functional proteins, like maltose-binding protein or human interferon alpha-2.IMPORTANCEA 5′ untranslated region of the mRNA of substrates of type I secretion systems (T1SS) drastically enhanced the secretion efficiency of the endogenously secreted protein. The identification of ribosomal protein S1 as the interaction partner of this 5′ untranslated region provides a rationale for the enhancement. This strategy furthermore can be transferred to fusion proteins allowing a broader, and eventually a more general, application of this system for secreting heterologous fusion proteins.

scholarly journals BastionHub: a universal platform for integrating and analyzing substrates secreted by Gram-negative bacteria

2020 ◽  
Vol 49 (D1) ◽  
pp. D651-D659
Author(s):  
Jiawei Wang ◽  
Jiahui Li ◽  
Yi Hou ◽  
Wei Dai ◽  
Ruopeng Xie ◽  
...  
Keyword(s):  
Rapid Development ◽  
Single Type ◽  
Computational Techniques ◽  
Type I ◽  
Gram Negative Bacteria ◽  
Bacterial Survival ◽  
Secretion Systems ◽  
Gram Negative ◽  
Relationship Analysis ◽  
Depth Analysis

Abstract Gram-negative bacteria utilize secretion systems to export substrates into their surrounding environment or directly into neighboring cells. These substrates are proteins that function to promote bacterial survival: by facilitating nutrient collection, disabling competitor species or, for pathogens, to disable host defenses. Following a rapid development of computational techniques, a growing number of substrates have been discovered and subsequently validated by wet lab experiments. To date, several online databases have been developed to catalogue these substrates but they have limited user options for in-depth analysis, and typically focus on a single type of secreted substrate. We therefore developed a universal platform, BastionHub, that incorporates extensive functional modules to facilitate substrate analysis and integrates the five major Gram-negative secreted substrate types (i.e. from types I–IV and VI secretion systems). To our knowledge, BastionHub is not only the most comprehensive online database available, it is also the first to incorporate substrates secreted by type I or type II secretion systems. By providing the most up-to-date details of secreted substrates and state-of-the-art prediction and visualized relationship analysis tools, BastionHub will be an important platform that can assist biologists in uncovering novel substrates and formulating new hypotheses. BastionHub is freely available at http://bastionhub.erc.monash.edu/.

scholarly journals A novel class of polymorphic toxins in Bacteroidetes

2020 ◽  
Vol 3 (4) ◽  
pp. e201900631
Author(s):  
Biswanath Jana ◽  
Dor Salomon ◽  
Eran Bosis
Keyword(s):  
Gut Microbiota ◽  
Unknown Function ◽  
Secretion System ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
New Class ◽  
Terminal Domain ◽  
Domain Of Unknown Function ◽  
Type Ix Secretion System ◽  
Encoding Gene

Bacteroidetes are Gram-negative bacteria that are abundant in the environment as well as in the gut microbiota of animals. Many bacteroidetes encode large proteins containing an N-terminal domain of unknown function, named TANFOR. In this work, we show that TANFOR-containing proteins carry polymorphic C-terminal toxin domains with predicted antibacterial and anti-eukaryotic activities. We also show that a C-terminal domain that is prevalent in TANFOR-containing proteins represents a novel family of antibacterial DNase toxins, which we named BaCT (Bacteroidetes C-terminal Toxin). Finally, we discover that TANFOR-encoding gene neighborhoods are enriched with genes that encode substrates of the type IX secretion system (T9SS), which is involved in exporting proteins from the periplasm across the outer membrane. Based on these findings, we conclude that TANFOR-containing proteins are a new class of polymorphic toxins, and we hypothesize that they are T9SS substrates.

scholarly journals Weaving of bacterial cellulose by the Bcs secretion systems

2021 ◽  
Author(s):  
Wiem Abidi ◽  
Lucía Torres-Sánchez ◽  
Axel Siroy ◽  
Petya Violinova Krasteva
Keyword(s):  
Bacterial Cellulose ◽  
Bacterial Species ◽  
Secretion System ◽  
Secretion Systems ◽  
Bacterial Signaling ◽  
Accessory Subunits ◽  
Domains Of Life ◽  
The 19Th Century ◽  
Structure Assembly ◽  
Review Current

Abstract Cellulose is the most abundant biological compound on Earth and while it is the predominant building constituent of plants, it is also a key extracellular matrix component in many diverse bacterial species. While bacterial cellulose was first described in the 19th century, it was not until this last decade that a string of structural works provided insights into how the cellulose synthase BcsA, assisted by its inner-membrane partner BcsB, senses c-di-GMP to simultaneously polymerize its substrate and extrude the nascent polysaccharide across the inner bacterial membrane. It is now established that bacterial cellulose can be produced by several distinct types of cellulose secretion systems and that in addition to BcsAB, they can feature multiple accessory subunits, often indispensable for polysaccharide production. Importantly, the last years mark significant progress in our understanding not only of cellulose polymerization per se, but also of the bigger picture of bacterial signaling, secretion system assembly, biofilm formation and host tissue colonization, as well as of structural and functional parallels of this dominant biosynthetic process between the bacterial and eukaryotic domains of life. Here we review current mechanistic knowledge on bacterial cellulose secretion with focus on the structure, assembly and cooperativity of Bcs secretion system components.

scholarly journals The Caulobacter crescentus Paracrystalline S-Layer Protein Is Secreted by an ABC Transporter (Type I) Secretion Apparatus

1998 ◽  
Vol 180 (12) ◽  
pp. 3062-3069 ◽  
Author(s):  
Peter Awram ◽  
John Smit
Keyword(s):  
Abc Transporter ◽  
Transport System ◽  
Protein Transport ◽  
Caulobacter Crescentus ◽  
Sequence Similarity ◽  
Secretion System ◽  
Cell Protein ◽  
Type I ◽  
Secretion Systems ◽  
Secretion Signal

ABSTRACT Caulobacter crescentus is a gram-negative bacterium that produces a two-dimensional crystalline array on its surface composed of a single 98-kDa protein, RsaA. Secretion of RsaA to the cell surface relies on an uncleaved C-terminal secretion signal. In this report, we identify two genes encoding components of the RsaA secretion apparatus. These components are part of a type I secretion system involving an ABC transporter protein. These genes, lying immediately 3′ of rsaA, were found by screening a Tn5 transposon library for the loss of RsaA transport and characterizing the transposon-interrupted genes. The two proteins presumably encoded by these genes were found to have significant sequence similarity to ABC transporter and membrane fusion proteins of other type I secretion systems. The greatest sequence similarity was found to the alkaline protease (AprA) transport system ofPseudomonas aeruginosa and the metalloprotease (PrtB) transport system of Erwinia chrysanthemi. TheprtB and aprA genes were introduced intoC. crescentus, and their products were secreted by the RsaA transport system. Further, defects in the S-layer protein transport system led to the loss of this heterologous secretion. This is the first report of an S-layer protein secreted by a type I secretion apparatus. Unlike other type I secretion systems, the RsaA transport system secretes large amounts of its substrate protein (it is estimated that RsaA accounts for 10 to 12% of the total cell protein). Such levels are expected for bacterial S-layer proteins but are higher than for any other known type I secretion system.

scholarly journals Functional Type 1 Secretion System Involved in Legionella pneumophila Virulence

2014 ◽  
Vol 197 (3) ◽  
pp. 563-571 ◽  
Author(s):  
Fabien Fuche ◽  
Anne Vianney ◽  
Claire Andrea ◽  
Patricia Doublet ◽  
Christophe Gilbert
Keyword(s):  
Legionella Pneumophila ◽  
Severe Form ◽  
Secretion System ◽  
Host Cells ◽  
Type I ◽  
Secretion Systems ◽  
Content Type ◽  
Legionnaires Disease ◽  
Infectious Cycle

Legionella pneumophilais a Gram-negative pathogen found mainly in water, either in a free-living form or within infected protozoans, where it replicates. This bacterium can also infect humans by inhalation of contaminated aerosols, causing a severe form of pneumonia called legionellosis or Legionnaires' disease. The involvement of type II and IV secretion systems in the virulence ofL. pneumophilais now well documented. Despite bioinformatic studies showing that a type I secretion system (T1SS) could be present in this pathogen, the functionality of this system based on the LssB, LssD, and TolC proteins has never been established. Here, we report the demonstration of the functionality of the T1SS, as well as its role in the infectious cycle ofL. pneumophila. Using deletion mutants and fusion proteins, we demonstrated that therepeats-in-toxin protein RtxA is secreted through an LssB-LssD-TolC-dependent mechanism. Moreover, fluorescence monitoring and confocal microscopy showed that this T1SS is required for entry into the host cell, although it seems dispensable to the intracellular cycle. Together, these results underline the active participation ofL. pneumophila, via its T1SS, in its internalization into host cells.

Sign in / Sign up

Export Citation Format

Share Document