Broad Proteomics

APEX peroxidase is a versatile tool for proximity labeling and electron microscopy (EM) but its requirement for toxic H2O2 is a liability. We now report LaccID, a multicopper oxidase evolved from an ancestral fungal laccase that oxidizes aromatic substrates using non-toxic O2 instead of H2O2. We use LaccID for EM imaging of cultured cells and fly brains, and for proteomic mapping of the changing surface composition of T cells that engage with tumor cells via antigen-specific T cell receptors.

TransitID is out today in Cell! This is a proximity labeling method for unbiased discovery of endogenous proteins that traffick from a defined “source” location to a defined “destination” location. TransitID uses sequential labeling by TurboID in the source, followed by a chase period (minutes to hours) and then 1-minute APEX tagging in the destination compartment. Proteins tagged by both enzymes are enriched with streptavidin and anti-fluorescein antibody, and identified by mass spec. We explore 4 intracellular and intercellular applications of TransitID: - discovery of locally translated mitochondrial proteins (translated at OMM, then imported into mito matrix) - mapping proteins whose cytoplasm-to-nucleus shuttling is dampened by stress - discovery of proteins that transit between nucleolus & stress granules during stress & stress recovery - analysis of proteins that traffic intercellularly bw tumor cells & macrophages Work of amazingly talented co-first authors @WeiQinChemBio and @CheahJoleen, and collaborators Steve Carr @namude & Paul Taylor authors.elsevier.com/a/1hKLc…

Very good 😃DIA MS session at #ASMS2023 Thanks to all the great speakers.