Import of TAT-Conjugated Propionyl Coenzyme A Carboxylase Using Models of Propionic Acidemia

<div>Propionic acidemia is caused by a deficiency of the enzyme propionyl</div><div>coenzyme A carboxylase (PCC) located in the mitochondrial matrix. Cell-penetrating</div><div>peptides, including transactivator of transcription (TAT), offer a potential to deliver a</div><div>cargo into the mitochondrion. Here, we investigated the delivery of an 66 PCC enzyme</div><div>into mitochondria using the HIV TAT peptide at several levels: into isolated</div><div>mitochondria, in patient fibroblast cells, and in a mouse model. Results from Western</div><div>blots and enzyme activity assays confirmed the import of TAT-PCC into mitochondria,</div><div>as well as into patient fibroblasts, where the colocalization of imported</div><div>TAT-PCC and mitochondria was also confirmed by confocal fluorescence microscopy.</div><div>Furthermore, a single-dose intraperitoneal injection into PCC-deficient mice decreased</div><div>the propionylcarnitine/acetylcarnitine (C3/C2) ratio toward the normal level.</div><div>These results show that a cell-penetrating peptide can deliver active multimeric enzyme</div><div>into mitochondria in vitro, in situ, and in vivo and push the size limit of intracellular</div><div>delivery achieved so far. Our results are promising for other mitochondrionspecific</div><div>deficiencies.</div>