scholarly journals Architecture of the active post‐translational Sec translocon

2020 ◽  
Author(s):  
Tsai‐Hsuan Weng ◽  
Wieland Steinchen ◽  
Birgitta Beatrix ◽  
Otto Berninghausen ◽  
Thomas Becker ◽  
...  
Keyword(s):  
Sec Translocon

scholarly journals Characterization of the annular lipid shell of the Sec translocon

2015 ◽  
Vol 1848 (10) ◽  
pp. 2050-2056 ◽  
Author(s):  
Irfan Prabudiansyah ◽  
Ilja Kusters ◽  
Antonella Caforio ◽  
Arnold J.M. Driessen
Keyword(s):  
Sec Translocon

scholarly journals Genetic Evidence for SecY Translocon-Mediated Import of Two Contact-Dependent Growth Inhibition (CDI) Toxins

mBio ◽  
2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Allison M. Jones ◽  
Petra Virtanen ◽  
Disa Hammarlöf ◽  
William J. Allen ◽  
Ian Collinson ◽  
...  
Keyword(s):  
Growth Inhibition ◽  
Target Cell ◽  
Bacterial Species ◽  
Genetic Evidence ◽  
Target Cells ◽  
Content Type ◽  
Sec Translocon ◽  
Dependent Growth ◽  
Cell Envelopes ◽  
Contact Dependent Growth Inhibition

ABSTRACT The C-terminal (CT) toxin domains of contact-dependent growth inhibition (CDI) CdiA proteins target Gram-negative bacteria and must breach both the outer and inner membranes of target cells to exert growth inhibitory activity. Here, we examine two CdiA-CT toxins that exploit the bacterial general protein secretion machinery after delivery into the periplasm. A Ser281Phe amino acid substitution in transmembrane segment 7 of SecY, the universally conserved channel-forming subunit of the Sec translocon, decreases the cytotoxicity of the membrane depolarizing orphan10 toxin from enterohemorrhagic Escherichia coli EC869. Target cells expressing secYS281F and lacking either PpiD or YfgM, two SecY auxiliary factors, are fully protected from CDI-mediated inhibition either by CdiA-CTo10EC869 or by CdiA-CTGN05224, the latter being an EndoU RNase CdiA toxin from Klebsiella aerogenes GN05224 that has a related cytoplasm entry domain. RNase activity of CdiA-CTGN05224 was reduced in secYS281F target cells and absent in secYS281F ΔppiD or secYS281F ΔyfgM target cells during competition co-cultures. Importantly, an allele-specific mutation in secY (secYG313W) renders ΔppiD or ΔyfgM target cells specifically resistant to CdiA-CTGN05224 but not to CdiA-CTo10EC869, further suggesting a direct interaction between SecY and the CDI toxins. Our results provide genetic evidence of a unique confluence between the primary cellular export route for unfolded polypeptides and the import pathways of two CDI toxins. IMPORTANCE Many bacterial species interact via direct cell-to-cell contact using CDI systems, which provide a mechanism to inject toxins that inhibit bacterial growth into one another. Here, we find that two CDI toxins, one that depolarizes membranes and another that degrades RNA, exploit the universally conserved SecY translocon machinery used to export proteins for target cell entry. Mutations in genes coding for members of the Sec translocon render cells resistant to these CDI toxins by blocking their movement into and through target cell membranes. This work lays the foundation for understanding how CDI toxins interact with the protein export machinery and has direct relevance to development of new antibiotics that can penetrate bacterial cell envelopes.

scholarly journals Partially inserted nascent chain unzips the lateral gate of the Sec translocon

EMBO Reports ◽  
2019 ◽  
Vol 20 (10) ◽  
Author(s):  
Lukas Kater ◽  
Benedikt Frieg ◽  
Otto Berninghausen ◽  
Holger Gohlke ◽  
Roland Beckmann ◽  
...  
Keyword(s):  
Nascent Chain ◽  
Sec Translocon ◽  
Lateral Gate

scholarly journals In vitro membrane protein synthesis inside Sec translocon-reconstituted cell-sized liposomes

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Naoki Ohta ◽  
Yasuhiko Kato ◽  
Hajime Watanabe ◽  
Hirotada Mori ◽  
Tomoaki Matsuura
Keyword(s):  
Protein Synthesis ◽  
Membrane Protein ◽  
Sec Translocon

scholarly journals Contributions of Francisella tularensis subsp. novicida Chitinases and Sec Secretion System to Biofilm Formation on Chitin

2009 ◽  
Vol 76 (2) ◽  
pp. 596-608 ◽  
Author(s):  
Jeffrey J. Margolis ◽  
Sahar El-Etr ◽  
Lydia-Marie Joubert ◽  
Emily Moore ◽  
Richard Robison ◽  
...  
Keyword(s):  
Carbon Source ◽  
Francisella Tularensis ◽  
Biofilm Formation ◽  
Secreted Proteins ◽  
Tularensis Subsp ◽  
Transmission Mechanisms ◽  
One Step ◽  
Sec Translocon ◽  
Mammalian Infection ◽  
Exogenous Sugar

ABSTRACT Francisella tularensis, the zoonotic cause of tularemia, can infect numerous mammals and other eukaryotes. Although studying F. tularensis pathogenesis is essential to comprehending disease, mammalian infection is just one step in the ecology of Francisella species. F. tularensis has been isolated from aquatic environments and arthropod vectors, environments in which chitin could serve as a potential carbon source and as a surface for attachment and growth. We show that F. tularensis subsp. novicida forms biofilms during the colonization of chitin surfaces. The ability of F. tularensis to persist using chitin as a sole carbon source is dependent on chitinases, since mutants lacking chiA or chiB are attenuated for chitin colonization and biofilm formation in the absence of exogenous sugar. A genetic screen for biofilm mutants identified the Sec translocon export pathway and 14 secreted proteins. We show that these genes are important for initial attachment during biofilm formation. We generated defined deletion mutants by targeting two chaperone genes (secB1 and secB2) involved in Sec-dependent secretion and four genes that encode putative secreted proteins. All of the mutants were deficient in attachment to polystyrene and chitin surfaces and for biofilm formation compared to wild-type F. novicida. In contrast, mutations in the Sec translocon and secreted factors did not affect virulence. Our data suggest that biofilm formation by F. tularensis promotes persistence on chitin surfaces. Further study of the interaction of F. tularensis with the chitin microenvironment may provide insight into the environmental survival and transmission mechanisms of this pathogen.

scholarly journals Characterization of Sec-Translocon-Dependent Extracytoplasmic Proteins of Rickettsia typhi

2008 ◽  
Vol 190 (18) ◽  
pp. 6234-6242 ◽  
Author(s):  
Nicole C. Ammerman ◽  
M. Sayeedur Rahman ◽  
Abdu F. Azad
Keyword(s):  
Host Cell ◽  
Mammalian Cells ◽  
Molecular Mechanisms ◽  
Host Cells ◽  
Transcriptional Analysis ◽  
Mammalian Host ◽  
Signal Peptides ◽  
Cell Infection ◽  
Rickettsia Typhi ◽  
Sec Translocon

ABSTRACT As obligate intracellular, vector-borne bacteria, rickettsiae must adapt to both mammalian and arthropod host cell environments. Deciphering the molecular mechanisms of the interactions between rickettsiae and their host cells has largely been hindered by the genetic intractability of these organisms; however, research in other gram-negative pathogens has demonstrated that many bacterial determinants of attachment, entry, and pathogenesis are extracytoplasmic proteins. The annotations of several rickettsial genomes indicate the presence of homologs of the Sec translocon, the major route for bacterial protein secretion from the cytoplasm. For Rickettsia typhi, the etiologic agent of murine typhus, homologs of the Sec-translocon-associated proteins LepB, SecA, and LspA have been functionally characterized; therefore, the R. typhi Sec apparatus represents a mechanism for the secretion of rickettsial proteins, including virulence factors, into the extracytoplasmic environment. Our objective was to characterize such Sec-dependent R. typhi proteins in the context of a mammalian host cell infection. By using the web-based programs LipoP, SignalP, and Phobius, a total of 191 R. typhi proteins were predicted to contain signal peptides targeting them to the Sec translocon. Of these putative signal peptides, 102 were tested in an Escherichia coli-based alkaline phosphatase (PhoA) gene fusion system. Eighty-four of these candidates exhibited signal peptide activity in E. coli, and transcriptional analysis indicated that at least 54 of the R. typhi extracytoplasmic proteins undergo active gene expression during infections of HeLa cells. This work highlights a number of interesting proteins possibly involved in rickettsial growth and virulence in mammalian cells.

Break on through to the other side – the Sec translocon

2004 ◽  
Vol 29 (5) ◽  
pp. 221-223 ◽  
Author(s):  
Jerry Eichler ◽  
Franck Duong
Keyword(s):  
The Other ◽  
Sec Translocon
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