Secretion signal and protein targeting in bacteria: a biological puzzle.

Alain Filloux * 3 Imperial College London, Division of Cell and Molecular Biology, Centre for Molecular Microbiology and 4 Infection, London, United Kingdom 5 6 *Mailing address: Imperial College London, Division of Cell and Molecular Biology, Centre for Molecular 7 Microbiology and Infection, South Kensington Campus, Flowers Building, SW7 2AZ London, United 8 Kingdom. Tel.: + 44 (0)2075949651; Fax: + 44 (0)2075943069; E-mail: [email protected]. 9 10 11 Protein targeting in bacterial cells should be a rather simple process, since few sub12 cellular compartments exist as compared to eukaryotic cells where targeting to the 13 nucleus, mitochondria, peroxysomes, endoplasmic reticulum or chloroplasts is required. 14 In most cases of bacterial protein targeting, the idea is that a tag is contained within the 15 protein, and this label gives the cell information about where the protein should be 16 delivered. This is reminiscent of the tagging of your luggage at the airport to have it 17 delivered where appropriate. 18 However, over the last few years, and especially in Gram negative bacteria, it has 19 emerged that the protein targeting process involves much more diverse tags than expected 20 and that the nature of some of them has still not been clearly elucidated. In this issue of 21 Journal of Bacteriology, findings by the group of Cecile Wandersman highlight very well 22 the complexity of this process (18). In essence, the targeting signal may sometimes be 23 simple and universal, such as the classical N terminal signal peptide, which is used to 24 Copyright © 2010, American Society for Microbiology and/or the Listed Authors/Institutions. All Rights Reserved. J. Bacteriol. doi:10.1128/JB.00565-10 JB Accepts, published online ahead of print on 4 June 2010