Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue.
Extracellular proteins are a subject of intense interest because of their essential roles in bacterial lifestyles. However, several terms related to secretion are used confusingly in the literature, and this is a topical issue in genomics and proteomics. Defining a secreted protein as actively translocated via a secretion system, here, we put into perspective that homologous translocation systems can result in radically different subcellular localizations of a secreted protein. We propose using standardized nomenclature for secretion systems from type I to type VIII for Gram-negative bacteria only, whereas the terms 'Sec' (secretion), 'Tat' (twin-arginine translocation), 'FEA' (flagella export apparatus), 'FPE' (fimbrilin-protein exporter), 'holin' (hole forming) and 'Wss' (WXG100 secretion system) should be applied to translocation systems across the cytoplasmic membrane of both Gram-positive and Gram-negative bacteria. Finally, we discuss why the term 'exoproteome' should be favoured over 'secretome' when describing the subset of proteins present in the extracellular milieu.
Desvaux
Mickaël
M
INRA (Institut National de la Recherche Agronomique), UR454 Microbiologie, Centre de Recherche Clermont-Ferrand, F-63122 Saint-Genès Champanelle, France. mdesvaux@clermont.inra.fr
Hébraud
Michel
M
Talon
Régine
R
Henderson
Ian R
IR
D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D005110:Extracellular Space / Q000378:metabolism*; D021381:Protein Transport; D013347:Subcellular Fractions / Q000378:metabolism*
D001426:Bacterial Proteins