Functional analysis of mutations in the human

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Functional analysis of mutations in the human

carnitine/acylcarnitine translocase in Aspergillus nidulans

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Péreza, Óscar Martíneza, Beatriz Romeroa, Israel Olivasa,

Ana M. Pedregosaa, Ferdinando Palmierib, Labordaa and J.

Ramón De Lucas, , a

a Departamento de Microbiología y Parasitología, Facultad de

Farmacia, Universidad de Alcalá, Carretera Madrid-Barcelona Km,

33.600, Campus Universitario, Alcalá de Henares ES-28871, Madrid,

Spain

b Dipartimento Fármaco-Biologico, Universita di Bari, Via E. Orbona

4, Bari 70125, Italy

Received 24 February 2003; accepted 28 March 2003. ; Available

online 9 May 2003.

Abstract

Deficiency of the carnitine/acylcarnitine translocase (CACT), the

most severe disorder of fatty acid & #946;-oxidation, is usually lethal in

both humans and animals, precluding the development of animal models

of the disease. In contrast, CACT deficiency is conditionally lethal

in the fungus Aspergillus nidulans, since loss-of-function mutations

in acuH, the translocase structural gene, do not prevent growth on

carbon sources other than ketogenic compounds, such as fatty acids.

Here, we describe the molecular characterization of extant acuH

alleles and the development of a fungal model for CACT deficiency

based on the ability of human CACT to fully complement, when

expressed at physiological levels, the growth defect of an A.

nidulans & #916;acuH strain on acetate and long-chain fatty acids. By

using growth tests and in vitro assays this model enabled us to

carry out a functional characterization of human CACT mutations

showing that it may be useful for distinguishing potentially

pathogenic human CACT missense mutations from neutral, single

residue substitution-causing polymorphisms.

Author Keywords: Carnitine/acylcarnitine translocase; Carnitine

carrier; Aspergillus nidulans; acuH; Model system; Genetic disease;

Fatty-acid metabolism; Oleate; Acetate; Human CACT