Abstract by John Wheelwright
Chemistry and Biochemistry
Identifying the Effects of Phosphorylation on the Cytosolic Tail of CMG2
Researchers observed that post-translational modifications (PTM) on the CMG2 cytosolic tail, specifically phosphorylation, is required for anthrax intoxication, a process initiated by endocytosis of Capillary Morphogenesis Gene 2 protein (CMG2). Four putative tyrosine phosphorylation sites have been identified in CMG2; they are: Y380, Y381, Y445, and Y463. We have determined which putative phosphorylation sites have the greatest effect on anthrax protective antigen uptake, which is required for intoxication. This was done by introducing constitutively active (Y to E mutations) and constitutively inactive mutations (Y to F mutations) via site directed mutagenesis. The individual mutants were transfected into HEK 293T cells that do not express any CMG2 or its homolog tumor endothelial marker 8 (TEM8). Using a flow cytometry-based assay to measure uptake of fluorescently labeled PA, we identified the inactive mutation of Y381F to have the greatest effect on PA endocytosis. This suggests that PTM at this site could be assisting in endocytosis.