title: The peroxisomal NAD+ carrier of Arabidopsis thaliana transports coenzyme A and its derivatives.
abstract: The peroxisomal protein PXN encoded by the Arabidopsis gene At2g39970 has very recently been found to transport NAD+, NADH, AMP and ADP. In this work we have reinvestigated the substrate specificity and the transport properties of PXN by using a wide range of potential substrates. Heterologous expression in bacteria followed by purification, reconstitution in liposomes, and uptake and efflux experiments revealed that PNX transports coenzyme A (CoA), dephospho-CoA, acetyl-CoA and adenosine 3', 5'-phosphate (PAP), besides NAD+, NADH, AMP and ADP. PXN catalyzed fast counter-exchange of substrates and much slower uniport and was strongly inhibited by pyridoxal 5'-phosphate, bathophenanthroline and tannic acid. Transport was saturable with a submillimolar affinity for NAD+, CoA and other substrates. The physiological role of PXN is probably to provide the peroxisomes with the essential coenzymes NAD+ and CoA.
authors.affiliation: Department of Biosciences, Biotechnology and Pharmacological Sciences, University of Bari, Via Orabona 4, 70125 Bari, Italy.
authors.forename: Gennaro
authors.initials: G
authors.lastname: Agrimi
authors.forename: Annamaria
authors.initials: A
authors.lastname: Russo
authors.forename: Ciro Leonardo
authors.initials: CL
authors.lastname: Pierri
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Palmieri
mesh_terms: D000105:Acetyl Coenzyme A / Q000378:metabolism*; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D009243:NAD / Q000378:metabolism*; D020675:Peroxisomes / Q000378:metabolism*; D021381:Protein Transport
chemical_list: D002352:Carrier Proteins; D009243:NAD; D000105:Acetyl Coenzyme A