Ubiquitination Events in the Regulation of a Paternally Supplied Toxin in C. elegans

Abstract

Successful development of an organism requires a highly complex coordination of various processes within the cell. The embryonic lethal toxin, PEEL-1, has been shown to disrupt early development in C. elegans and ultimately results in the death of the developing embryo without rescue by the antitoxin, ZEEL-1. Using a transgenic worm strain expressing PEEL-1::GFP, we have demonstrated the complete pathway through which PEEL-1 is ubiquitinated and degraded. The first step in ubiquitination is through the sole ubiquitin activating enzyme found in C. elegans, UBA-1. Using RNAi techniques, we then determined UBC-18 to be the conjugating enzyme responsible in the ubiquitin cascade. Subsequently, C17H11.4, C27A12.6, and HECD-1 work in coordination as ligation enzymes. With PEEL-1 being a transmembrane protein and inaccessible to the proteasome, we demonstrated that PEEL-1 is likely being degraded via autophagy. We also show that MO and PEEL-1 levels decrease throughout the one and two cell stages of early development. Finally, we found data that suggests that the increased lethality associated with ubc-18 knockdown can be attributed to the persistence of PEEL-1.