Optimizing purification of the peripheral membrane protein FAM92A1 fused to a modified spidroin tag

• Cryo-electron microscopy has revolutionized structural biology. In particular structures of proteins at themembrane interface have been a major contribution of cryoEM. Yet, visualization and characterization of peripheralmembrane proteins remains challenging; mostly because there is no unified purification strategy forthese proteins. FAM92A1 is a novel peripheral membrane protein that binds to the mitochondrial inner membrane.There, FAM92A1 dimers bind to the membrane and play an essential role in regulating the mitochondrialultrastructure. Curiously, FAM92A1 has also an important function in ciliogenesis. FAM92A1 is part of themembrane bending Bin1/Amphiphsyin/RVS (BAR) domain protein family. Currently, there is no structure ofFAM92A1, mostly because FAM92A1 is unstable and insoluble at high concentrations, like many BAR domainproteins. Yet, pure and concentrated protein is a necessity for screening to generate samples suitable for structuredetermination. Here, we present an optimized purification and expression strategy for dimeric FAM92A1. To ourknowledge, we are the first to use the spidroin tag NT* to successfully purify a peripheral membrane protein. Ourresults show that NT* not only increases solubility but stabilizes FAM92A1 as a dimer. FAM92A1 fused to NT* isactive because it is able to efficiently bend membranes. Taken together, our strategy indicates that this is apossible avenue to express and purify other challenging BAR domain proteins.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biokemi och molekylärbiologi (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biochemistry and Molecular Biology (hsv//eng)

Nyckelord

Biotechnology

Bioteknologi

Biotechnology

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