A subunit of eukaryotic translation initiation factor 2α-phosphatase (CreP/PPP1R15B) regulates membrane traffic.
The constitutive reverter of eIF2α phosphorylation (CReP)/PPP1r15B targets the catalytic subunit of protein phosphatase 1 (PP1c) to phosphorylated eIF2α (p-eIF2α) to promote its dephosphorylation and translation initiation. Here, we report a novel role and mode of action of CReP. We found that CReP regulates uptake of the pore-forming Staphylococcus aureus α-toxin by epithelial cells. This function was independent of PP1c and translation, although p-eIF2α was involved. The latter accumulated at sites of toxin attack and appeared conjointly with α-toxin in early endosomes. CReP localized to membranes, interacted with phosphomimetic eIF2α, and, upon overexpression, induced and decorated a population of intracellular vesicles, characterized by accumulation of N-(lissamine rhodamine B sulfonyl)phosphatidylethanolamine (N-Rh-PE), a lipid marker of exosomes and intralumenal vesicles of multivesicular bodies. By truncation analysis, we delineated the CReP vesicle induction/association region, which comprises an amphipathic α-helix and is distinct from the PP1c interaction domain. CReP was also required for exocytosis from erythroleukemia cells and thus appears to play a broader role in membrane traffic. In summary, the mammalian traffic machinery co-opts p-eIF2α and CReP, regulators of translation initiation.
Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
Nicole
N
Kloft
Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
Claudia
C
Neukirch
Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
Gisela
G
von Hoven
Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
Wiesia
W
Bobkiewicz
Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany.
Silvia
S
Weis
Department of Immunology, Morphology Section, Paul Ehrlich-Institute, 63225 Langen, Germany.
Klaus
K
Boller
Institute of Medical Microbiology and Hygiene, University Medical Center, Johannes Gutenberg-University Mainz, Hochhaus am Augustusplatz, 55131 Mainz, Germany. Electronic address: husmann@uni-mainz.de.
Matthias
M
Husmann
D000818:Animals; D001427:Bacterial Toxins / Q000378:metabolism; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D011992:Endosomes / Q000235:genetics / Q000378:metabolism*; D004847:Epithelial Cells / Q000166:cytology / Q000378:metabolism*; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D020014:K562 Cells; D010442:Peptide Chain Initiation, Translational / Q000502:physiology*; D010766:Phosphorylation / Q000502:physiology; D054645:Protein Phosphatase 1 / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000502:physiology; D011817:Rabbits; D013211:Staphylococcus aureus / Q000378:metabolism
D001427:Bacterial Toxins; D015852:Eukaryotic Initiation Factor-2; D054645:Protein Phosphatase 1