Binding of coatomer by the PEX11 C-terminus is not required for function

Microbodies are single membrane-bound organelles found in eukaryotes from trypanosomes to man. Although they have diverse roles in metabolism, the mechanisms and molecules involved in membrane biogenesis and matrix protein import are conserved. Similarly, the basic mechanisms and structures involved in vesicular transport are similar throughout eukaryotic evolution. The PEX11 proteins are required for the division of microbodies in trypanosomes, yeast and mammals, and a role of coatomer in this process has been suggested. We show here that the binding of trypanosome, yeast and bovine coatomers to selected peptides is identical. Coatomer binds to the C-termini of trypanosome PEX11 and rat Pex11alpha, but not yeast Pex11p or human Pex11beta. Mutations of the C-terminus of trypanosome PEX11 that eliminated coatomer binding did not affect function in yeast or trypanosomes. Thus binding of coatomer to the C-terminus of PEX11 is not required for PEX11 function.