ALO1 encodes D-arabinono-1,4-lactone oxidase (called ALO in other organisms) (EC 1.1.3.37), a mitochondrial protein (1, 2) that converts D-arabinono-1,4-lactone to dehydro-D-arabinono-1,4-lactone, the enantiomer of ascorbate (vitamin C) (3, 4). Saccharomyces cerevisiae does not normally synthesize ascorbate, but Alo1p is sufficiently promiscuous that it can convert a number of related substrates to either dehydro-D-arabinono-1,4-lactone or ascorbate, depending on the chirality of the substrate (1, 5, 6). Like ascorbate, dehydro-D-arabinono-1,4-lactone is an antioxidant. Deletion of ALO1 results in increased sensitivity to oxidative stress (1) and an increased rate of gross chromosomal rearrangements, implying that Alo1p suppresses oxidative damage of DNA (7). Transcription of ALO1 is not regulated in response to oxidative stress (1). Alo1p exists as a monomer embedded in the mitochondrial membrane (1) and binds FAD (1, 8).

Please note: There is a history of disagreement regarding the name of the product synthesized by Alo1p. It has been called D-erythroascorbic acid (or D-erythroascorbate) in the literature (1, 9). The ChEBI chemical database at the European Bioinformatics Institute (see http://www.ebi.ac.uk/chebi/searchFreeText.do?searchString=17803 ) changed the name to dehydro-D-arabinono-1,4-lactone in 2008, based on the advice of the International Union of Biochemistry and Molecular Biology (IUBMB; see http://www.chem.qmul.ac.uk/iubmb/enzyme/EC1/1/3/37.html ). The IUBMB changed the name from D-erythroascorbate to dehydro-D-arabinono-1,4-lactone in May 2008, because they decided that the name D-erythroascorbate refers to a 6-carbon compound and not a 5-carbon compound as the product is described in the literature (1).

Last updated: 2009-02-02