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

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.

Different transmembrane domains determine the specificity and efficiency of the cleavage activity of the γ-secretase subunit presenilin.

The γ-secretase complex catalyzes the intramembrane cleavage of C99, a carboxy-terminal fragment of the amyloid precursor protein. Two paralogs of its catalytic subunit presenilin (PS1 and PS2) are expressed which are autocatalytically cleaved into an N-terminal and a C-terminal fragment during maturation of γ-secretase. In this study, we compared the efficiency and specificity of C99 cleavage by PS1- and PS2-containing γ-secretases.

Author Correction: Identifying ionic interactions within a membrane using BLaTM, a genetic tool to measure homo- and heterotypic transmembrane helix-helix interactions.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Identifying ionic interactions within a membrane using BLaTM, a genetic tool to measure homo- and heterotypic transmembrane helix-helix interactions.

The assembly of integral membrane protein complexes is frequently supported by transmembrane domain (TMD) interactions. Here, we present the BLaTM assay that measures homotypic as well as heterotypic TMD-TMD interactions in a bacterial membrane. The system is based on complementation of β-lactamase fragments genetically fused to interacting TMDs, which confers ampicillin resistance to expressing cells.