Common Non-classically Secreted Bacterial Proteins with Experimental Evidence

The non-classically secreted proteins are the proteins that are located in the extracellular milieu despite the absence of known signal peptides or other targeting peptides. Numerous experimental studies have discovered many non-classically secreted proteins, but there are many inconsistencies in these reports even on a specific organism. In order to reduce the impact of artefactual contamination of protein samples and cell lysis, this review listed 45 common non-classically secreted proteins. The list of non-classically secreted proteins was complied from studies carried out by different groups in various bacterial species. The complied list can provide a reliable experimental material for further research on non-classical protein secretion. It is noticeable that some of these proteins are hyper-secreted when expressed in specific species or under some induction conditions. So we also discussed the possibilities of using the non-classical secretion pathway for the production of recombinant proteins in the review.