Molecular basis of the glycosomal targeting of PEX11 and its mislocalization to mitochondrion in trypanosomes

Chethan K Krishna; Nadine Schmidt; Bettina G Tippler; Wolfgang Schliebs; Martin Jung; Konstanze F Winklhofer; Ralf Erdmann; Vishal C Kalel

doi:10.3389/fcell.2023.1213761

Molecular basis of the glycosomal targeting of PEX11 and its mislocalization to mitochondrion in trypanosomes

Front Cell Dev Biol. 2023 Aug 17:11:1213761. doi: 10.3389/fcell.2023.1213761. eCollection 2023.

Authors

Chethan K Krishna¹, Nadine Schmidt¹, Bettina G Tippler¹, Wolfgang Schliebs¹, Martin Jung², Konstanze F Winklhofer³, Ralf Erdmann¹, Vishal C Kalel¹

Affiliations

¹ Department of Systems Biochemistry, Institute for Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.
² Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany.
³ Department Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Faculty of Medicine, Ruhr University Bochum, Bochum, Germany.

Abstract

PEX19 binding sites are essential parts of the targeting signals of peroxisomal membrane proteins (mPTS). In this study, we characterized PEX19 binding sites of PEX11, the most abundant peroxisomal and glycosomal membrane protein from Trypanosoma brucei and Saccharomyces cerevisiae. TbPEX11 contains two PEX19 binding sites, one close to the N-terminus (BS1) and a second in proximity to the first transmembrane domain (BS2). The N-terminal BS1 is highly conserved across different organisms and is required for maintenance of the steady-state concentration and efficient targeting to peroxisomes and glycosomes in both baker's yeast and Trypanosoma brucei. The second PEX19 binding site in TbPEX11 is essential for its glycosomal localization. Deletion or mutations of the PEX19 binding sites in TbPEX11 or ScPEX11 results in mislocalization of the proteins to mitochondria. Bioinformatic analysis indicates that the N-terminal region of TbPEX11 contains an amphiphilic helix and several putative TOM20 recognition motifs. We show that the extreme N-terminal region of TbPEX11 contains a cryptic N-terminal signal that directs PEX11 to the mitochondrion if its glycosomal transport is blocked.

Keywords: MTS; PEX19; PMP; glycosome; mPTS; peroxin; peroxisome.

Grants and funding

This project work has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 812968—PerICo (to CK, and RE). The work was supported by DFG grant FOR1905 to RE.