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The Single ENTH‐Domain Protein of Trypanosomes; Endocytic Functions and Evolutionary Relationship with Epsin
Author(s) -
GabernetCastello Carme,
Dacks Joel B.,
Field Mark C.
Publication year - 2009
Publication title -
traffic
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.677
H-Index - 130
eISSN - 1600-0854
pISSN - 1398-9219
DOI - 10.1111/j.1600-0854.2009.00910.x
Subject(s) - biology , clathrin , microbiology and biotechnology , endocytosis , internalization , endocytic cycle , ubiquitin , receptor , biochemistry , gene
Epsin N‐terminal homology (ENTH) domains occur in proteins of either the epsin or epsin‐related (epsinR) form. They principally function in clathrin‐mediated trafficking and membrane deformation. Both epsin and epsinR possess clathrin‐binding motifs, but only epsin incorporates a ubiquitin‐interaction motif (UIM). To better understand the origins of ENTH‐domain proteins and their functions, we performed detailed comparative genomics and phylogenetics on the epsin family. The epsin ENTH‐UIM configuration is an architecture restricted to yeast and animals. Further, we undertook functional analysis in Trypanosoma brucei (T. brucei) , a divergent organism possessing a single ENTH‐domain protein (TbEpsinR). TbEpsinR has a cellular location similar to both epsin and epsinR at plasma membrane clathrin budding sites and endosomal compartments, and associates with clathrin, as demonstrated by coimmunoprecipitation. Knockdown of TbEpsinR leads to a significant decrease in the intracellular pools of multiple surface antigens, without affecting bulk membrane internalization. Therefore, despite lacking the UIM, TbEpsinR maintains a similar role to metazoan epsin in endocytosis and participates as a clathrin‐associated adaptor. We suggest that recruitment of a UIM to the ENTH‐domain proteins was not essential for participation in endocytosis of ubiquitylated molecules, and is presumably a specific innovation restricted to higher eukaryotes.