Identification of Human Fumarylacetoacetate Hydrolase Domain-containing Protein 1 (FAHD1) as a Novel Mitochondrial Acylpyruvase

Haymo Pircher,Grit D Straganz,Daniela Ehehalt,Geneviève Morrow,Robert M Tanguay,Pidder Jansen-Dürr

doi:10.1074/jbc.m111.264770

Abstract

The human fumarylacetoacetate hydrolase (FAH) domain-containing protein 1 (FAHD1) is part of the FAH protein superfamily, but its enzymatic function is unknown. In the quest for a putative enzymatic function of FAHD1, we found that FAHD1 exhibits acylpyruvase activity, demonstrated by the hydrolysis of acetylpyruvate and fumarylpyruvate in vitro, whereas several structurally related compounds were not hydrolyzed as efficiently. Conserved amino acids Asp-102 and Arg-106 of FAHD1 were found important for its catalytic activity, and Mg(2+) was required for maximal enzyme activity. FAHD1 was found expressed in all tested murine tissues, with highest expression in liver and kidney. FAHD1 was also found in several human cell lines, where it localized to mitochondria. In summary, the current work identified mammalian FAHD1 as a novel mitochondrial enzyme with acylpyruvate hydrolase activity.

Highlights

Human FAH domain-containing protein 1 (FAHD1) is a member of the fumarylacetoacetate hydrolase (FAH) enzyme superfamily with unknown enzymatic activity
In the quest for a putative enzymatic function of FAHD1, we found that FAHD1 exhibits acylpyruvase activity, demonstrated by the hydrolysis of acetylpyruvate and fumarylpyruvate in vitro, whereas several structurally related compounds were not hydrolyzed as efficiently
FAHD1 was found in several human cell lines, where it localized to mitochondria

Summary

Background

Human FAHD1 is a member of the FAH enzyme superfamily with unknown enzymatic activity. The superfamily is characterized by a highly conserved structure of the catalytic center referred to as the FAH fold, named after the best characterized mammalian enzyme FAH, the founding member of the family, which hydrolyzes fumarylacetoacetate to yield fumarate and acetoacetate [1] This ␤-diketone hydrolase reaction forms the final step of the tyrosine catabolism pathway. Within the same study revealing the FAHD1 structure [8], a hydroxylase or decarboxylase function (possibly involved in aromatic amino acid catabolism) was tentatively suggested based on the properties of the putative active site, with the physiologically present. We determined both the tissue expression profile and the subcellular localization of FAHD1

EXPERIMENTAL PROCEDURES

RESULTS

DISCUSSION