The Intermitochondrial Localization of Human Pantothenate Kinase 2

Abstract

Pantothenate kinase (PanK) catalyzes the first step in Coenzyme A (CoA) biosynthesis. Three genes express the four catalytically active isoforms of mammalian PanK; PanK1α1β 2, and 3. PanK activity is feedback inhibited by CoA, with each isoform exhibiting a distinct sensitivity to the CoA thioester pool. Mutations in the human PanK 2 gene result in a progressive and fatal neurodegenerative disease, called PKAN. Our lab and others have shown that human PanK2 is associated with mitochondria. The localization of PanK2 was investigated using a human neuroblastoma cell, SHSY. Selective permeabilization of mitochondrial compartments with increasing concentrations of digitonin, combined with Proteinase K digestion of exposed proteins, revealed that PanK2 was located in the intermitochondrial space. PanK enzyme activity in isolated mitochondrial fractions was cryptic, and restoration of full activity accompanied detergent solubilization of the mitochondrial membrane. Long‐chain acylcarnitine has been shown to activate PanK2 in vitro. Current experiments are investigating the impact of acylcarnitine on the metabolic activity of overexpressed PanK2 in SHSY cells. The localization of PanK2 places it in close proximity to the site of acylcarnitine formation, thereby enabling its rapid activation. Supported by GM62896, CA21765, and ALSAC.