Biology subjects

Fuchs, A. C. D.

Publications and source records attributed to Fuchs, A. C. D..

3 recordsLinked to original sources

bioRxiv2024

Enzymatic Protein Fusions with 100% Product Yield

The protein ligase Connectase can be used to fuse proteins to small molecules, solid carriers, or other proteins. Compared to other protein ligases, it offers greater substrate specificity, higher catalytic efficiency, and catalyzes no side reactions. However, its reaction is reversible, resulting in only 50% fusion product from two equally abundant educts. Here, we present a simple method to reliably obtain 100% fusion product in 1:1 conjugation reactions. This method is efficient for protein-protein or protein-peptide fusions at the N-or C-termini. It enables the generation of defined and completely labeled antibody conjugates with one fusion partner on each chain. The reaction requires short incubation times with small amounts of enzyme and is effective even at low substrate concentrations and at low temperatures. With these characteristics, it presents a valuable new tool for bioengineering.

biochemistry↗

bioRxiv2024

A new class of receptors: Lipids regulate mammalian Gsalpha-stimulated adenylyl cyclase activities via their membrane anchors

The biosynthesis of cAMP by mammalian membrane-bound adenylyl cyclases (mACs) is predominantly regulated by G-protein-coupled-receptors (GPCRs). Up to now the two hexahelical transmembrane domains of mACs were considered to fix the enzyme to membranes. Here we show that the transmembrane domains serve in addition as signal receptors and transmitters of lipid signals that control Gs-stimulated mAC activities. We identify aliphatic fatty acids and anandamide as receptor ligands of mAC isoforms 1 to 7 and 9. The ligands enhance (mAC isoforms 2, 3, 7, and 9) or attenuate (isoforms 1, 4, 5, and 6) Gs-stimulated mAC activities in vitro and in vivo. Substitution of the stimulatory membrane receptor of mAC3 by the inhibitory receptor of mAC5 results in a ligand inhibited mAC5-mAC3 chimera. Thus, we discovered a new class of membrane receptors in which two signaling modalities are at a crossing, direct tonic lipid and indirect phasic GPCR-Gs signaling regulating the biosynthesis of cAMP.

biochemistry↗

bioRxiv2020

The proteasome-related Connectase is a fast and specific protein ligase

Genetic methods allow the recombinant production of any protein of interest, but yield the full-length construct in one step and are limited to native amino acids. For the "on demand" generation of chimeric, immobilized, fluorophore-conjugated or segmentally labeled proteins, these proteins must be modified using chemical1,2, (split) intein2,3, split domain4 or enzymatic methods5. While each of these options comes with its own advantages and drawbacks, ligase enzymes are often used where small ligation motifs and good chemoselectivity are required. However, applications with the reference enzyme Sortase A are impeded by poor catalytic efficiencies, low substrate specificities and side reactions6,7. Here, we present the discovery of Connectase, a monomeric proteasome homolog that ligates substrates via a highly conserved KDPGA motif originally identified in methyltransferase A (MtrA), a key enzyme in archaeal methanogenesis. Connectase displays nanomolar affinity and thus great specificity for its substrates, allowing efficient protein-protein ligations even in complex solutions and at low substrate concentrations. Compared to an optimized Sortase variant, Connectase catalyzes such ligations at substantially higher rates, with higher yields but without detectable side reactions and thus presents a valuable new tool for protein conjugations.

biochemistry↗