Recognition and Chaperoning by Pex19, Followed by Trafficking and Membrane Insertion of the Peroxisome Proliferation Protein, Pex11

Abstract

Pex11, an abundant peroxisomal membrane protein (PMP), is required for division of peroxisomes and is robustly imported to peroxisomal membranes. We present a comprehensive analysis of how the Pichia pastoris Pex11 is recognized and chaperoned by Pex19, targeted to peroxisome membranes and inserted therein. We demonstrate that Pex11 contains one Pex19-binding site (Pex19-BS) that is required for Pex11 insertion into peroxisomal membranes by Pex19, but is non-essential for peroxisomal trafficking. We provide extensive mutational analyses regarding the recognition of Pex19-BS in Pex11 by Pex19. Pex11 also has a second, Pex19-independent membrane peroxisome-targeting signal (mPTS) that is preserved among Pex11-family proteins and anchors the human HsPex11γ to the outer leaflet of the peroxisomal membrane. Thus, unlike most PMPs, Pex11 can use two mechanisms of transport to peroxisomes, where only one of them depends on its direct interaction with Pex19, but the other does not. However, Pex19 is necessary for membrane insertion of Pex11. We show that Pex11 can self-interact, using both homo- and/or heterotypic interactions involving its N-terminal helical domains. We demonstrate that Pex19 acts as a chaperone by interacting with the Pex19-BS in Pex11, thereby protecting Pex11 from spontaneous oligomerization that would otherwise cause its aggregation and subsequent degradation.

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

“…In yeast, Pex11p contains a single PEX19-BS near its N-terminus, while in the other Sc PEX11-family members, Pex25p and Pex27p, binding of PEX19 occurs far distal from the N-terminus ( Rottensteiner et al, 2004 ). A recent study identified a classical PEX19-BS near the N-terminus of Pichia pastoris PEX11 ( Zientara-Rytter et al, 2022 ). However, the study also showed that amphipathic helix 4 (H4) located in the C-terminal region of Pp PEX11, functions as a second, PEX19-independent mPTS, which is preserved among PEX11-family proteins ( Zientara-Rytter et al, 2022 ).…”

“…A recent study identified a classical PEX19-BS near the N-terminus of Pichia pastoris PEX11 ( Zientara-Rytter et al, 2022 ). However, the study also showed that amphipathic helix 4 (H4) located in the C-terminal region of Pp PEX11, functions as a second, PEX19-independent mPTS, which is preserved among PEX11-family proteins ( Zientara-Rytter et al, 2022 ). Thus, unlike most PMPs, PEX11 of Pichia pastoris can use two mechanisms of transport to peroxisomes, where only one of them depends on its direct interaction with PEX19, but the other does not.…”

Convergent and divergent mechanisms of peroxisomal and mitochondrial division

“…Domains with specific functions/characteristics are shown and retained in the other figures. VD, variable domain; TPR, tetratricopeptide repeat; TMD, transmembrane domain; AH1–H4, putative amphipathic helices based on the work on P. pastoris Pex11 ( Zientara-Rytter et al, 2022 ); *Conserved, N-terminal AH in Pex11, termed Pex11-Amph, necessary for peroxisomal fission in vivo and for tubulation of liposomes with a lipid consistency resembling the peroxisomal membrane ( Opaliński et al, 2011 ); CC, coiled-coil; NBD, nucleotide-binding domain. No protein domains have been reported for Pex27.…”

“…Pex11 proteins possess at least four amphipathic helices (AHs; AH1–AH4; Zientara-Rytter et al, 2022 ) with lipid-binding and membrane-bending properties ( Koch and Brocard, 2011 ), analogous to BAR-domain proteins required for the scission of clathrin-coated vesicles during endocytosis ( Suetsugu et al, 2010 ). In general, two types of AHs, reported in many proteins, can be involved in the induction of membrane curvature and sensing this curvature ( Drin et al, 2007 ).…”

Delineating transitions during the evolution of specialised peroxisomes: Glycosome formation in kinetoplastid and diplonemid protists

“…Conserved are three peptide sequences in the N-terminal region with propensity to form amphipathic helices that, in Penicillium chrysogenum , are essential for the membrane remodelling capacity of PEX11 ( Opalinski et al, 2011 ; Schrader et al, 2012 ). An amphipathic helix near the C-terminus is also conserved, but its function is still unknown ( Zientara-Rytter et al, 2022 ).…”