Trypanosomes contain two highly different isoforms of peroxin PEX13 involved in glycosome biogenesis

We previously identified the peroxin PEX13 in Trypanosoma brucei. Although lacking some features considered typical of PEX13s, it appeared functional in the biogenesis of glycosomes, the peroxisome-like organelles of trypanosomatids. Here we report the identification of a very different trypanosomatid PEX13, not containing the commonly encountered PEX13 SH3 domain but having other typical features. It is readily detected with the jackhmmer database search program, but not with PSI-BLAST. This is the first time different PEX13 isoforms are reported in a single organism. We show that this PEX13.2, like the PEX13.1 previously described, is associated with glycosomes and that its depletion by RNA interference affects the biogenesis of the organelles and viability of trypanosomes. The features considered typical of PEX13s are discussed.Structured summary of protein interactionsPex19physically interacts with Pex13.2 by two hybrid (View interaction)Pex13.1physically interacts with Pex13.2 by two hybrid (View interaction)

► Trypanosoma brucei possesses two PEX13 isoforms with insignificant similarity.
► In contrast to TbPEX13.1, yeast and mammalian PEX13s, TbPEX13.2 has no SH3 domain.
► A glycine-rich region containing YG motifs is the principal feature common to PEX13s.
► Both T. brucei PEX13 isoforms are located in glycosomes.
► Both PEX13s are essential for glycosome biogenesis and trypanosome viability.