Molecular insights into type I secretion systems

Lenders, Michael H. H.; Reimann, Sven; Smits, Sander H. J.; Schmitt, Lutz

doi:10.1515/hsz-2013-0171

Cited by 23 publications

(12 citation statements)

References 99 publications

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“…Substrates are generally considered to lack NT cleavable signal peptides, with potential SSs located within their CT. However, T1SS substrates can possess either NT or CT SSs, with their cognate ABC transporters (and possibly MFPs) containing domain architectures designed to accommodate particular SSs (Kanonenberg et al ., 2013, Lenders et al ., 2013, Thomas et al ., 2013). The ABC transporters of T1SSs have recently been categorized into three groups (Kanonenberg et al ., 2013) .…”

Section: Sec-independent Secretory Pathwaysmentioning

confidence: 99%

Secretome of obligate intracellularRickettsia

et al. 2014

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The genus Rickettsia (Alphaproteobacteria; Rickettsiales; Rickettsiaceae) is comprised of obligate intracellular parasites, with virulent species of interest both as causes of emerging infectious diseases and for their potential deployment as bioterrorism agents. Currently there are no effective commercially available vaccines, with treatment limited primarily to tetracycline antibiotics, though others (e.g., josamycin, ciprofloxacin, chloramphenicol and azithromycin) are also effective. Much of the recent research geared towards understanding mechanisms underlying rickettsial pathogenicity has centered on characterization of secreted proteins that directly engage eukaryotic cells. Herein, we review all aspects of the Rickettsia secretome, including six secretion systems, 19 characterized secretory proteins, and potential moonlighting proteins identified on surfaces of multiple Rickettsia species. Employing bioinformatics and phylogenomics, we present novel structural and functional insight on each secretion system. Unexpectedly, our investigation revealed that the majority of characterized secretory proteins have not been assigned to their cognate secretion pathways. Furthermore, for most secretion pathways, the requisite signal sequences mediating translocation are poorly understood. As a blueprint for all known routes of protein translocation into host cells, this resource will assist research aimed at uniting characterized secreted proteins with their apposite secretion pathways. Furthermore, our work will help in the identification of novel secreted proteins involved in rickettsial “life on the inside”.

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Section: Sec-independent Secretory Pathwaysmentioning

confidence: 99%

Secretome of obligate intracellularRickettsia

et al. 2014

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“…In Gram-negative bacteria, PCATs interact with an outer membrane protein and another accessory protein to form a type 1 secretion system (T1SS) that secretes proteins from the cytosol directly into the extracellular space 6 . The substrates secreted by the T1SS range from small antibiotic peptides (microcins) to large adhesion proteins of 900 kilodaltons (kDa).…”

mentioning

confidence: 99%

Crystal structures of a polypeptide processing and secretion transporter

Lin

Huang

Chen

2015

Nature

113

164

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Bacteria secrete peptides and proteins to communicate, to poison competitors, and to manipulate host cells. Among the various protein-translocation machineries, the peptidase-containing ATP-binding cassette transporters (PCATs) are appealingly simple. Each PCAT contains two peptidase domains that cleave the secretion signal from the substrate, two transmembrane domains that form a translocation pathway, and two nucleotide-binding domains that hydrolyse ATP. In Gram-positive bacteria, PCATs function both as maturation proteases and exporters for quorum-sensing or antimicrobial polypeptides. In Gram-negative bacteria, PCATs interact with two other membrane proteins to form the type 1 secretion system. Here we present crystal structures of PCAT1 from Clostridium thermocellum in two different conformations. These structures, accompanied by biochemical data, show that the translocation pathway is a large α-helical barrel sufficient to accommodate small folded proteins. ATP binding alternates access to the transmembrane pathway and also regulates the protease activity, thereby coupling substrate processing to translocation.

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“…The paradigm of T1SS that translocates RTX toxins is the hemolysin A secretion machinery found in uropathogenic E. coli strains. HlyA is a 1024 amino acid (110 kDa) pore-forming toxin, which harbors six conserved GG repeats 11 . The HlyA T1SS is composed of the ABC transporter hemolysin B (HlyB), the MFP hemolysin D (HlyD) and TolC, the endogenously expressed OMP.…”

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confidence: 99%

In vivo quantification of the secretion rates of the hemolysin A Type I secretion system

Lenders

Beer

Smits

et al. 2016

Sci Rep

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Type 1 secretion systems (T1SS) of Gram-negative bacteria secrete a broad range of substrates into the extracellular space. Common to all substrates is a C-terminal secretion sequence and nonapeptide repeats in the C-terminal part that bind Ca2+ in the extracellular space, to trigger protein folding. Like all T1SS, the hemolysin A (HlyA) T1SS of Escherichia coli consists of an ABC transporter, a membrane fusion protein and an outer membrane protein allowing the one step translocation of the substrate across both membranes. Here, we analyzed the secretion rate of the HlyA T1SS. Our results demonstrate that the rate is independent of substrate-size and operates at a speed of approximately 16 amino acids per transporter per second. We also demonstrate that the rate is independent of the extracellular Ca2+ concentration raising the question of the driving force of substrate secretion by T1SS in general.

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Molecular insights into type I secretion systems

Cited by 23 publications

References 99 publications

Secretome of obligate intracellularRickettsia

Secretome of obligate intracellularRickettsia

Crystal structures of a polypeptide processing and secretion transporter

In vivo quantification of the secretion rates of the hemolysin A Type I secretion system

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