Type 9 secretion system (T9SS) is one of the recently characterized secretion systems found restricted to the Bacteroidetes phylum (environmentally and economically relevant bacterial lineage) [Sato et al (2009), Sato et al (2013), McBride & Zhu (2013)]. T9SS is known to play a central role in the secretion of proteins involved in diverse bacterial functions, including survival, movement and pathogenicity. The bacterial movement associated with T9SS is termed as gliding motility [Sato et al (2009)]. It is interesting to note that not all bacteria having T9SS exhibit gliding motility.

Here, we present a computational tool which predicts the presence of T9SS, gliding motility or proteins secreted via T9SS from proteome of bacteria. We identified 28 proteins associated with T9SS or gliding motility from published literature. From these 28 proteins, we designated 6 proteins (GldK, GldL, GldM, GldN, SprA, SprE) as mandatory components for the presence of T9SS and an additional 5 proteins (GldB, GldD, GldH, GldJ, SprT) as mandatory components for presence of gliding motility. Using this knowledge, we predicted 402 of 693 completely sequenced Bacteroidetes strains to have T9SS. Out of these 402, 327 Bacteroidetes strains are predicted to also have gliding motility. We also visualized the location of the identfied protein components in the genome of respective bacteria. Further, we also predicted the proteins secreted via T9SS across 402 Bacteroidetes strains having T9SS. For the predicted secreted proteins, we provide the protein identifier from PATRIC or NCBI Protein, UniProt identifier, AlphaFold DB identifier, type of evidence, type of C-terminal domain (CTD) and the presence of Carbohydrate-Active enZYmes (CAZy) domain.

The predicted results can be viewed in the Browse section. The computational tool developed here can be accessed in the Prediction section. A standalone version of the tool is available on our GitHub page.

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