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bioRxiv · 10.1101/2023.07.28.550932

Functional and topological analysis of PSENEN, the fourth subunit of the gamma-secretase complex

Serneels, L.·Bammens, L.·Zwijsen, A.·Tolia, A.·Chavez Gutierrez, L.·De Strooper, B.
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Abstract

The {gamma}-secretase complexes are intramembrane cleaving proteases involved in the generation of the A{beta} peptides in Alzheimers Disease. The complex consists of four subunits, with Presenilin, harboring the catalytic site. Here, we study the role of the smallest subunit, PSENEN or Presenilin enhancer 2 (PEN-2), encoded by the gene Psenen, in vivo and in vitro. We find a profound Notch-deficiency phenotype in Psenen-/- embryos confirming the essential role of PSENEN in the {gamma}-secretase complex. We used Psenen-/- fibroblasts to explore the structure-function of PSENEN by the Scanning Cysteine Accessibility Method. Glycine22 and Proline27 which border the membrane domains 1 and 2 of PSENEN are involved in complex formation and stabilization of {gamma}-secretase. The hairpin structured hydrophobic membrane domains 1 and 2 are exposed to a water-containing cavity in the complex, while transmembrane domain 3 is not water exposed. We finally demonstrate the essential role of PSENEN for the cleavage activity of the complex. PSENEN is more than a structural component of the {gamma}-secretase complex and might contribute to the catalytic mechanism of the enzyme.

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Serneels, L., Bammens, L., Zwijsen, A., Tolia, A., Chavez Gutierrez, L., De Strooper, B.. 2023-07-28. Functional and topological analysis of PSENEN, the fourth subunit of the gamma-secretase complex. https://doi.org/10.1101/2023.07.28.550932

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