Type III secretion: what's in a name?

Institut National de la Recherche Agronomique, Centre de Recherche de Clermont-Ferrand-Theix, UR 454, Unité de Microbiologie, F-63122 Saint-Genès Champanelle, France.
Trends in Microbiology (Impact Factor: 9.19). 05/2006; 14(4):157-60. DOI: 10.1016/j.tim.2006.02.009
Source: PubMed


The term 'type III secretion' has seen widespread use. However, problems persist in nomenclature. We propose that the standard abbreviation for this kind of secretion should be 'T3S' and that 'type III secretion system' should be abbreviated to 'T3SS'. There is also a need for a new terminology to distinguish flagellar and non-flagellar type III secretion systems that reflects their common evolutionary ancestry but does not obscure their distinctive features. Finally, the use of the term 'type III secretion' to cover cytolysin-mediated translocation is to be deprecated because an authentic type III secretion system has already been described in gram-positive bacteria, namely the flagellar protein export apparatus.

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Available from: Michel Hébraud
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    • "The Type III protein secretion system (T3SS) is conserved in many Gram-negative plant and animal pathogenic bacteria [4]. The T3SS is subdivided into (i) the non-flagellar T3SS (T3aS) involved in the assembly of the injectisome or hypersensitive response and pathogenicity (Hrp) pilus, and (ii) the flagellar T3SS (T3bS), responsible for assembly of the flagellum [5]. The T3SS spans both bacterial membranes and is associated with an extracellular filamentous appendage, termed ‘needle’ in animal pathogens and ‘Hrp pilus’ in plant pathogens, which is predicted to function as a protein transport channel to the host-pathogen interface [4]. "
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    ABSTRACT: Several bacterial plant pathogens colonize their hosts through the secretion of effector proteins by a Type III protein secretion system (T3SS). The role of T3SS in bacterial pathogenesis is well established but whether this system is involved in multicellular processes, such as bacterial biofilm formation has not been elucidated. Here, the phytopathogen Xanthomonas citri subsp. citri (X. citri) was used as a model to gain further insights about the role of the T3SS in biofilm formation. The capacity of biofilm formation of different X. citri T3SS mutants was compared to the wild type strain and it was observed that this secretion system was necessary for this process. Moreover, the T3SS mutants adhered proficiently to leaf surfaces but were impaired in leaf-associated growth. A proteomic study of biofilm cells showed that the lack of the T3SS causes changes in the expression of proteins involved in metabolic processes, energy generation, exopolysaccharide (EPS) production and bacterial motility as well as outer membrane proteins. Furthermore, EPS production and bacterial motility were also altered in the T3SS mutants. Our results indicate a novel role for T3SS in X. citri in the modulation of biofilm formation. Since this process increases X. citri virulence, this study reveals new functions of T3SS in pathogenesis.
    Full-text · Article · Apr 2014 · BMC Microbiology
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    • "vesicatoria is a type III secretion (T3S) system which translocates approximately 30 effector proteins into the host cell cytosol (Büttner and Bonas 2010; Ryan et al. 2011). T3S systems are conserved in many gram-negative plant-and animal-pathogenic bacteria and are evolutionarily related to the bacterial flagellum, which is also referred to as a T3S system (Chevance and Hughes 2008; Desvaux et al. 2006). Flagellar T3S systems are connected via an extracellular hook to the flagellar filament, which is the key bacterial motility organelle. "
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    ABSTRACT: Pathogenicity of the Gram-negative plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria depends on a membrane-spanning type III secretion (T3S) system, which translocates effector proteins into eukaryotic host cells. In this study, we characterized the T3S system component HrcV, which is a member of the YscV/FlhA family of inner membrane proteins. HrcV consists of eight transmembrane helices and a cytoplasmic region (HrcVC). Mutant and protein-protein interaction studies showed that HrcVC is essential for protein function and binds to T3S substrates including the early substrate HrpB2, the pilus protein HrpE and effector proteins. Furthermore, HrcVC interacts with itself and with components and control proteins of the T3S apparatus. The interaction of HrcVC with HrpB2, HrpE and T3S system components depends on amino acid residues in a conserved motif, designated FHIPEP (flagella/hypersensitive response/invasion proteins export pore), which is located in a cytoplasmic loop between transmembrane helix four and five of HrcV. Mutations in the FHIPEP motif abolish HrcV function but do not affect the interaction of HrcVC with effector proteins.
    Preview · Article · Jun 2013 · Molecular Plant-Microbe Interactions
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    • "The relatively low sequence similarity and frequent horizontal transfer among bacteria makes it difficult to identify T3SS orthologs [13,14]. Most importantly, different nomenclature and categorization methods/terms have created confusion and difficulty in literature search as well as in data interpretation using relevant information obtained in other genera [13,14]. A unified platform integrating various sources of information is urgently needed to facilitate T3SS related research. "
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    ABSTRACT: Type III Secretion System (T3SS), which plays important roles in pathogenesis or symbiosis, is widely expressed in a variety of gram negative bacteria. However, lack of unique nomenclature for T3SS genes has hindered T3SS related research. It is necessary to set up a knowledgebase integrating T3SS-related research data to facilitate the communication between different research groups interested in different bacteria. A T3SS-related Database (T3DB) was developed. T3DB serves as an integrated platform for sequence collection, function annotation, and ortholog classification for T3SS related apparatus, effector, chaperone and regulatory genes. The collection of T3SS-containing bacteria, T3SS-related genes, function annotation, and the ortholog information were all manually curated from literature. BPBAac, a highly efficient T3SS effector prediction tool, was also implemented. T3DB is the first systematic platform integrating well-annotated T3SS-related gene and protein information to facilitate T3SS and bacterial pathogenecity related research. The newly constructed T3 ortholog clusters may faciliate effective communication between different research groups and will promote de novo discoveries. Besides, the manually-curated high-quality effector and chaperone data are useful for feature analysis and evolutionary studies of these important proteins.
    Full-text · Article · Apr 2012 · BMC Bioinformatics
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