Secretion and subcellular localizations of bacterial proteins: a semantic awareness issue

• Published in: Trends in microbiology (Regular ed.) Vol. 17; no. 4; pp. 139 - 145
• Main Authors: Desvaux, Mickaël, Hébraud, Michel, Talon, Régine, Henderson, Ian R.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.04.2009; Elsevier
• Subjects: Bacteria; Bacteria - metabolism; Bacterial Proteins - metabolism; Bacteriology; Extracellular Space - metabolism; Internal Medicine; Life Sciences; Microbiology and Parasitology; Protein Transport; Subcellular Fractions - metabolism
• ISSN: 0966-842X; 1878-4380
• DOI: 10.1016/j.tim.2009.01.004

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.