Interaction of Substrates with γ-Secretase at the Level of Individual Transmembrane Helices—A Methodological Approach

• Published in: International journal of molecular sciences 2023-09, Vol.24 (18), p.14396
• Main Authors: Pauli, Theresa M., Julius, Ayse, Costa, Francesco, Eschrig, Sabine, Moosmüller, Judith, Fischer, Lea, Schanzenbach, Christoph, Schmidt, Fabian C., Ortner, Martin, Langosch, Dieter
• Format: Article
• Language: English
• Subjects: Amyloid beta-protein; BLaTM; heterotypic interaction; Interfaces; intramembrane proteolysis; Membrane proteins; Peptides; Proteases; Proteins; substrate recognition; transmembrane domain; γ secretase
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms241814396

Intramembrane proteases, such as γ secretase, typically recruit multiple substrates from an excess of single-span membrane proteins. It is currently unclear to which extent substrate recognition depends on specific interactions of their transmembrane domains (TMDs) with TMDs of a protease. Here, we investigated a large number of potential pairwise interactions between TMDs of γ secretase and a diverse set of its substrates using two different configurations of BLaTM, a genetic reporter system. Our results reveal significant interactions between TMD2 of presenilin, the enzymatic subunit of γ secretase, and the TMD of the amyloid precursor protein, as well as of several other substrates. Presenilin TMD2 is a prime candidate for substrate recruitment, as has been shown from previous studies. In addition, the amyloid precursor protein TMD enters interactions with presenilin TMD 4 as well as with the TMD of nicastrin. Interestingly, the Gly-rich interfaces between the amyloid precursor protein TMD and presenilin TMDs 2 and 4 are highly similar to its homodimerization interface. In terms of methodology, the economics of the newly developed library-based method could prove to be a useful feature in related future work for identifying heterotypic TMD−TMD interactions within other biological contexts.