1.C.132. The TseL Toxin (TseL) Family Comparison of multiple Vibrio cholerae strains indicated that effectors are encoded in T6SS effector modules on mobile genetic elements. Unterweger et al. 2015 identified a diverse group of chimeric T6SS adaptor proteins required for the translocation of diverse effectors encoded in modules. An example for a T6SS effector that requires T6SS adaptor protein 1 (Tap-1) is TseL found in pandemic V. cholerae O1 serogroup strains and other clinical isolates. Unterweger et al. 2015 proposed a model in which Tap-1 is required for loading TseL onto the secretion apparatus. After T6SS-mediated TseL export is completed, Tap-1 is retained in the bacterial cell to load other T6SS machines. It acts on prokaryotic as well as eukaryotic target cells (Miyata et al. 2013; Dong et al. 2013). The TseL activity is not required for T6SS activity (Liang et al. 2019). TseL, but no other effectors or physical puncture, triggers a tit-for-tat response of P. aeruginosa H1-T6SS. Although E. coli is sensitive to all periplasmically expressed effectors, P. aeruginosa is most sensitive to TseL alone. Kamal et al. 2020 identified a number of stress response pathways that confer protection against TseL.
This family belongs to the Lipase/Toxin Superfamily.
References:
Dong, T.G., B.T. Ho, D.R. Yoder-Himes, and J.J. Mekalanos. (2013). Identification of T6SS-dependent effector and immunity proteins by Tn-seq in Vibrio cholerae. Proc. Natl. Acad. Sci. USA 110: 2623-2628.
Kamal, F., X. Liang, K. Manera, T.T. Pei, H. Kim, L.G. Lam, A. Pun, S.J. Hersch, and T.G. Dong. (2020). Differential Cellular Response to Translocated Toxic Effectors and Physical Penetration by the Type VI Secretion System. Cell Rep 31: 107766.
Liang, X., F. Kamal, T.T. Pei, P. Xu, J.J. Mekalanos, and T.G. Dong. (2019). An onboard checking mechanism ensures effector delivery of the type VI secretion system in. Proc. Natl. Acad. Sci. USA 116: 23292-23298.
Miyata, S.T., D. Unterweger, S.P. Rudko, and S. Pukatzki. (2013). Dual expression profile of type VI secretion system immunity genes protects pandemic Vibrio cholerae. PLoS Pathog 9: e1003752.
Unterweger, D., B. Kostiuk, R. Ötjengerdes, A. Wilton, L. Diaz-Satizabal, and S. Pukatzki. (2015). Chimeric adaptor proteins translocate diverse type VI secretion system effectors in Vibrio cholerae. EMBO. J. 34: 2198-2210.
Examples:
TC#	Name	Organismal Type	Example
1.C.132.1.1	The TseL toxin of 641 aas and 1 or 2 central TMSs. See family description for properties.		TseL of Vibrio cholerae

1.C.132.1.2	Uncharacterized protein, probably a lipase, of 775 aas and from 0 to 4 possible TMSs.		UP of Spirodela intermedia

1.C.132.1.3	Uncharacterized protein, probable lipase, of 340 aas and 3 probable TMSs, one in the middle and two near the C-terminus of the protein.		*UP of Momordica charantia* (bitter melon)**

1.C.132.1.4	Uncharacterized protein of 275 aas and possibly 2 TMSs.		UP of Paramecium sonneborni

1.C.132.1.5	Lipase domain protein, putative of 1867 aas and ~ 12 TMSs.		Lipase of Leishmania panamensis

1.C.132.1.6	Triacylglycerol lipase OBL1-like of 482 aas and ~ 7 TMSs in a 2 + 2 + 3 TMS arrangement.		Lipase of Hibiscus syriacus

1.C.132.1.7	Lipase family protein of 371 aas and one N-terminal TMS, with a second possible central TMS.		Lipase of Crateriforma spongiae