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: 8.43). 05/2006; 14(4):157-60. DOI: 10.1016/j.tim.2006.02.009
Source: PubMed

ABSTRACT 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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Bacterial colonization of biotic or abiotic surfaces results from two quite distinct physiological processes, namely bacterial adhesion and biofilm formation. Broadly speaking, a biofilm is defined as the sessile development of microbial cells. Biofilm formation arises following bacterial adhesion but not all single bacterial cells adhering reversibly or irreversibly engage inexorably into a sessile mode of growth. Among molecular determinants promoting bacterial colonization, surface proteins are the most functionally diverse active components. To be present on the bacterial cell surface, though, a protein must be secreted in the first place. Considering the close association of secreted proteins with their cognate secretion systems, the secretome (which refers both to the secretion systems and their protein substrates) is a key concept to apprehend the protein secretion and related physiological functions. The protein secretion systems are here considered in light of the differences in the cell-envelope architecture between diderm-LPS (archetypal Gram-negative), monoderm (archetypal Gram-positive) and diderm-mycolate (archetypal acid-fast) bacteria. Besides, their cognate secreted proteins engaged in the bacterial colonization process are regarded from single protein to supramolecular protein structure as well as the non-classical protein secretion. This state-of-the-art on the complement of the secretome (the secretion systems and their cognate effectors) involved in the surface colonization process in diderm-LPS and monoderm bacteria paves the way for future research directions in the field.
    Frontiers in Microbiology 01/2013; 4:303. · 3.90 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    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.
    BMC Microbiology 04/2014; 14(1):96. · 2.98 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Listeria monocytogenes has a dichotomous lifestyle, existing as an ubiquitous saprophytic species and as an opportunistic intracellular pathogen. Besides its capacity to grow in a wide range of environmental and stressful conditions, L. monocytogenes has the ability to adhere to and colonize surfaces. Morphotype variation to elongated cells forming rough colonies has been reported for different clinical and environmental isolates, including biofilms. This cell differentiation is mainly attributed to the reduced secretion of two SecA2-dependent cell-wall hydrolases, CwhA and MurA. SecA2 is a non-essential SecA paralogue forming an alternative translocase with the primary Sec translocon. Following investigation at temperatures relevant to its ecological niches, i.e. infection (37°C) and environmental (20°C) conditions, inactivation of this SecA2-only protein export pathway led, despite reduced adhesion, to the formation of filamentous biofilm with aerial structures. Compared to the wild type strain, inactivation of the SecA2 pathway promoted extensive cell aggregation and sedimentation. At ambient temperature, this effect was combined with the abrogation of cell motility resulting in elongated sedimented cells, which got knotted and entangled together in the course of filamentous-biofilm development. Such a cell differentiation provides a decisive advantage for listerial surface colonization under environmental condition. As further discussed, this morphotypic conversion has strong implication on listerial physiology and is also of potential significance for asymptomatic human/animal carriage.
    Environmental Microbiology 08/2013; 15(9). · 6.24 Impact Factor


Available from
May 16, 2014